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Document and Entity Information - USD ($) $ in Thousands	12 Months Ended
Document and Entity Information - USD ($) $ in Thousands	Dec. 31, 2018	Feb. 28, 2019	Oct. 03, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	UPWK
Entity Registrant Name	Upwork Inc.
Entity Central Index Key	0001627475
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		106,692,030
Entity Public Float			$ 900,000
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Well-known Seasoned Issuer	No

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 129,128	$ 21,595
Funds held in escrow, including funds in transit	98,186	87,195
Trade and client receivables – net of allowance of $2,832 and $1,577 as of December 31, 2018 and 2017, respectively	22,315	30,762
Prepaid expenses and other current assets	6,253	4,574
Total current assets	255,882	144,126
Property and equipment, net	10,815	3,514
Goodwill	118,219	118,219
Intangible assets, net	6,004	8,672
Other assets, noncurrent	653	658
Total assets	391,573	275,189
Current liabilities:
Accounts payable	2,073	462
Escrow funds payable	98,186	87,195
Debt, current	5,671	10,342
Accrued expenses and other current liabilities	20,948	16,030
Deferred revenue	722	614
Total current liabilities	127,600	114,643
Debt, noncurrent	18,239	23,491
Other liabilities, noncurrent	1,989	1,936
Total liabilities	147,828	140,070
Commitments and contingencies (Note 5)
Redeemable convertible preferred stock, $0.0001 par value; 76,141,345 shares authorized as of December 31, 2017; 61,279,079 shares issued and outstanding as of December 31, 2017; aggregate liquidation preference of $120,047 as of December 31, 2017	0	166,486
Stockholders’ equity (deficit):
Common stock, $0.0001 par value; 490,000,000 and 150,000,000 shares authorized as of December 31, 2018 and 2017, respectively; 106,454,321 and 33,740,323 shares issued and outstanding as of December 31, 2018 and 2017, respectively	11	3
Additional paid-in capital	387,233	92,222
Accumulated deficit	(143,499)	(123,592)
Total stockholders’ equity (deficit)	243,745	(31,367)
Total liabilities, redeemable convertible preferred stock, and stockholders' equity (deficit)	$ 391,573	$ 275,189

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 2,832	$ 1,577
Redeemable convertible preferred stock, par value (in dollars per share)		$ 0.0001
Redeemable convertible preferred stock, shares authorized (in shares)		76,141,345
Redeemable convertible preferred stock, shares issued (in shares)		61,279,079
Redeemable convertible preferred stock, shares outstanding (in shares)		61,279,079
Liquidation preference		$ 120,047
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	490,000,000	150,000,000
Common stock, shares issued (in shares)	106,454,321	33,740,323
Common stock, shares outstanding (in shares)	106,454,321	33,740,323

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Revenue	$ 253,354	$ 202,552	$ 164,445
Cost of revenue	81,458	65,443	62,578
Gross profit	171,896	137,109	101,867
Operating expenses:
Research and development	55,488	45,604	37,902
Sales and marketing	72,963	53,044	37,437
General and administrative	49,336	37,334	35,446
Provision for transaction losses	5,821	4,250	5,550
Total operating expenses	183,608	140,232	116,335
Loss from operations	(11,712)	(3,123)	(14,468)
Interest expense	2,038	960	858
Other expense, net	6,142	62	908
Total loss before income taxes	(19,892)	(4,145)	(16,234)
Income tax benefit (provision)	(15)	22	1
Net loss	(19,907)	(4,123)	(16,233)
Premium paid on repurchase of redeemable convertible preferred stock	0	(6,506)	0
Net loss attributable to common stockholders	$ (19,907)	$ (10,629)	$ (16,233)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.38)	$ (0.32)	$ (0.51)
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted	52,327,518	32,944,714	32,071,604

CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Redeemable convertible preferred stock, beginning balance at Dec. 31, 2015	$ 178,785
Redeemable convertible preferred stock, beginning balance (in shares) at Dec. 31, 2015	65,464,387
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of redeemable convertible preferred stock in connection with the initial public offering	$ 0
Redeemable convertible preferred stock, ending balance (in shares) at Dec. 31, 2016	65,464,387
Redeemable convertible preferred stock, ending balance at Dec. 31, 2016	$ 178,785
Beginning balance at Dec. 31, 2015	(21,434)	$ 3	$ 81,799	$ (103,236)
Beginning balance (in shares) at Dec. 31, 2015		31,905,645
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and common stock warrants	$ 270		270
Issuance of common stock upon exercise of stock options (in shares)	272,591	272,591
Stock-based compensation expense	$ 7,266		7,266
Conversion of redeemable convertible preferred stock warrant in connection with the initial public offering	0
Net loss	(16,233)			(16,233)
Ending balance at Dec. 31, 2016	(30,131)	$ 3	89,335	(119,469)
Ending balance (in shares) at Dec. 31, 2016		32,178,236
Increase (Decrease) in Temporary Equity [Roll Forward]
Exercise of warrant on redeemable convertible preferred stock and related reclassification of redeemable convertible preferred stock warrant liability	$ 404
Exercise of warrant on redeemable convertible preferred stock and related reclassification of redeemable convertible preferred stock warrant liability (in shares)	83,181
Repurchase and retirement of redeemable convertible preferred stock	$ (12,703)
Repurchase and retirement of redeemable convertible preferred stock (in shares)	(4,268,489)
Conversion of redeemable convertible preferred stock in connection with the initial public offering	$ 0
Redeemable convertible preferred stock, ending balance (in shares) at Dec. 31, 2017	61,279,079
Redeemable convertible preferred stock, ending balance at Dec. 31, 2017	$ 166,486
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and common stock warrants	$ 2,547		2,547
Issuance of common stock upon exercise of stock options (in shares)	1,554,944	1,554,944
Issuance of common stock to consultants (in shares)		7,143
Repurchase and retirement of redeemable convertible preferred stock	$ (6,506)		(6,506)
Stock-based compensation expense	6,846		6,846
Conversion of redeemable convertible preferred stock warrant in connection with the initial public offering	0
Net loss	(4,123)			(4,123)
Ending balance at Dec. 31, 2017	(31,367)	$ 3	92,222	(123,592)
Ending balance (in shares) at Dec. 31, 2017		33,740,323
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of redeemable convertible preferred stock in connection with the initial public offering	$ (166,486)
Conversion of redeemable convertible preferred stock in connection with the initial public offering (in shares)	(61,279,079)
Redeemable convertible preferred stock, ending balance (in shares) at Dec. 31, 2018	0
Redeemable convertible preferred stock, ending balance at Dec. 31, 2018	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options and common stock warrants	$ 8,160	$ 1	8,159
Issuance of common stock upon exercise of stock options (in shares)	3,522,631	3,567,917
Stock-based compensation expense	$ 10,361		10,361
Issuance of common stock in connection with the initial public offering, net of discounts and commissions	109,381	$ 1	109,380
Issuance of common stock in connection with the initial public offering, net of discounts and commissions (in shares)		7,840,908
Costs related to the initial public offering	(6,282)		(6,282)
Conversion of redeemable convertible preferred stock warrant in connection with the initial public offering	7,160		7,160
Conversion of redeemable convertible preferred stock in connection with the initial public offering	166,486	$ 6	166,480
Conversion of redeemable convertible preferred stock in connection with the initial public offering (in shares)		61,279,079
Issuance of common stock for settlement of RSUs (in shares)		38,742
Shares withheld related to net share settlement of RSUs	(247)		(247)
Shares withheld related to net share settlement of RSUs (in shares)		(12,648)
Net loss	(19,907)			(19,907)
Ending balance at Dec. 31, 2018	$ 243,745	$ 11	$ 387,233	$ (143,499)
Ending balance (in shares) at Dec. 31, 2018		106,454,321

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (19,907)	$ (4,123)	$ (16,233)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Provision for transaction losses	5,110	4,250	5,550
Depreciation and amortization	4,949	4,186	8,462
Amortization of debt issuance costs	77	49	0
Change in fair value of redeemable convertible preferred stock warrant liability	6,056	118	114
Change in fair value of Tides Foundation common stock warrant	226	0	0
Stock-based compensation expense	10,361	6,846	7,266
Loss on disposal of fixed assets	91	66	32
Changes in operating assets and liabilities:
Trade and client receivables	3,506	(8,860)	(8,320)
Prepaid expenses and other assets	(1,292)	(479)	(450)
Accounts payable	1,609	74	(578)
Accrued expenses and other liabilities	2,849	(6,148)	7,057
Deferred revenue	109	20	248
Net cash provided by (used in) operating activities	13,744	(4,001)	3,148
CASH FLOWS FROM INVESTING ACTIVITIES:
Decrease (increase) in restricted cash	(444)	208	371
Purchases of property and equipment	(3,002)	(1,830)	(846)
Internal-use software and platform development costs	(3,839)	(489)	0
Net cash used in investing activities	(7,285)	(2,111)	(475)
CASH FLOWS FROM FINANCING ACTIVITIES:
Changes in funds held in escrow, including funds in transit	(10,991)	(27,362)	4,725
Changes in escrow funds payable	10,991	27,362	(4,725)
Proceeds from exercises of stock options and common stock warrant	8,160	2,547	270
Proceeds from exercise of redeemable convertible preferred stock warrant	0	260	0
Repurchase of redeemable convertible preferred stock	0	(19,208)	0
Taxes paid related to net share settlement of RSUs	(247)	0	0
Proceeds from borrowings on debt	15,000	34,000	17,000
Payment of debt issuance costs	0	(177)	(38)
Repayment of debt	(25,000)	(17,000)	(12,000)
Proceeds from the initial public offering, net of discounts and commissions	109,381	0	0
Payments of costs related to the initial public offering	(6,220)	(41)	0
Net cash provided by financing activities	101,074	381	5,232
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	107,533	(5,731)	7,905
Cash and cash equivalents, beginning of year	21,595	27,326	19,421
Cash and cash equivalents, end of year	129,128	21,595	27,326
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid for income taxes	13	55	0
Cash paid for interest	1,976	847	1,330
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Property and equipment purchased but not yet paid	2,945	114	0
Reclassification of redeemable convertible preferred stock warrant liability to redeemable convertible preferred stock	0	144	0
Conversion of redeemable convertible preferred stock warrant in connection with the initial public offering	7,160	0	0
Conversion of redeemable convertible preferred stock in connection with the initial public offering	166,486	0	0
Unpaid deferred offering costs	$ 0	$ 25	$ 0

Organization and Description of Business	12 Months Ended
Organization and Description of Business	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	Organization and Description of Business Upwork Inc. (the “Company” or “Upwork”) operates an online marketplace that enables businesses (“clients”) to find and work with highly-skilled independent professionals (“freelancers,” and, together with clients, “users”). The Company was originally incorporated in the state of Delaware in December 2013 prior to and in connection with the combination (the “Elance-oDesk Combination”) of Elance, Inc. (“Elance”) and oDesk Corporation (“oDesk”). The Company changed its name to Elance-oDesk, Inc. (“Elance-oDesk”) shortly before the Elance-oDesk Combination in March 2014, and later to Upwork Inc. in May 2015. In 2015, the Company relaunched as Upwork and commenced consolidation of its two operating platforms. In 2016, following completion of the platform consolidation, the Company began operating under a single platform. The Company is headquartered in Mountain View, California. Unless otherwise expressly stated or the context otherwise requires, the terms “Upwork” and the “Company” in these notes to the consolidated financial statements refer to Upwork and its wholly-owned subsidiaries. Initial Public Offering In October 2018, the Company completed its initial public offering (“IPO”), in which the Company issued and sold an aggregate of 7,840,908 of the Company’s common stock, including 1,022,727 shares pursuant to the exercise of the underwriters’ option to purchase additional shares, The shares were sold to the underwriters at the IPO price of $15.00 per share less an underwriting discount of $1.05 per share. The Company received aggregate net proceeds of $109.4 million from the IPO after deducting underwriting discounts and commissions but before deducting offering expenses payable by the Company.

Basis of Presentation and Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Basis of Presentation and Summary of Significant Accounting Policies

Basis of Presentation and Principles of Consolidation

The consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and include the accounts of Upwork and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make certain estimates, judgments, and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expenses during the periods presented. Such estimates include, but are not limited to, the useful lives of assets; assessment of the recoverability of long-lived assets; goodwill impairment; allowance for doubtful accounts; liabilities relating to transaction losses; the valuation of warrants; stock-based compensation; and accounting for income taxes. Management bases its estimates on historical experience and on various other assumptions that management believes to be reasonable under the circumstances. The Company evaluates its estimates, assumptions, and judgments on an ongoing basis using historical experience and other factors and revises them when facts and circumstances dictate. Actual results could materially differ from these estimates.

Cash and Cash Equivalents

The Company holds its cash in checking and interest-bearing accounts and investments in money market funds with maturities of 90 days or less from the date of purchase.

Restricted Cash

The Company maintained restricted cash of $2.7 million and $2.3 million related to cash reserve requirements under the California Department of Business Oversight’s escrow laws and regulations, collateral for letters of credit issued in conjunction with operating leases, and restricted cash balances under foreign currency forward contract obligations as of December 31, 2018 and 2017, respectively. Short-term restricted cash included in prepaid expenses and other current assets was $2.2 million and $1.8 million as of December 31, 2018 and 2017, respectively, and long-term restricted cash included in other assets, noncurrent was $0.5 million as of December 31, 2018 and 2017.

Funds Held in Escrow, Including Funds in Transit

The Company maintains its users’ funds held in escrow in demand or checking accounts at U.S. financial institutions, as well as four California licensed money transmitters. The balance in these accounts was in excess of federally insured limits as of December 31, 2018 and 2017. Users’ funds held in escrow are denominated exclusively in U.S. dollars.

The Company is an internet escrow agent and is therefore required to hold its users’ escrowed funds and escrow funds in transit in trust as an asset and record a corresponding liability for escrow funds payable on its consolidated balance sheets. Escrow funds in transit arise due to the time it takes to clear transactions through external payment networks. When clients fund their escrow account using credit cards, there is a clearing period before the cash is received and settled. Accordingly, the funds are treated as escrow funds in transit until the transaction is settled to the escrow trust bank account or, in the case of international credit card settlements, to the Company’s bank accounts. Escrow regulations require the Company to fund the trust with its own operating cash if there is ever a shortage due to the timing of cash receipts from clients for completed hourly billings. As of December 31, 2018 and 2017, the Company recorded $98.2 million and $87.2 million, respectively, as funds held in escrow, including funds in transit.

Escrow Funds Payable

Escrow funds payable represent user funds that are held in escrow by the Company on behalf of both freelancers and clients. Escrow funds payable to freelancers are comprised primarily of funds available to be withdrawn by freelancers for work performed and paid by clients. Escrow funds payable to clients primarily represent deposits received from certain clients to set up an account or to apply toward future payments to freelancers upon completion of the project defined and agreed between the client and the freelancer.

Concentration of Risk

Financial instruments that subject the Company to concentration of risk consist primarily of cash, restricted cash, funds held in escrow, including funds in transit, and trade and client receivables. The Company maintains its cash balances with large, high-credit quality financial institutions and other payment companies. At times, such deposits may be in excess of federally insured limits. The Company has not experienced any losses on its deposits. Credit risk on trade receivables is limited as a result of the large size of the Company’s client base as well as a large portion of payments made in the form of pre-authorized credit cards. The Company performs ongoing credit evaluation of its clients and maintains allowances for potential credit losses. For any receivables that are deemed not collectible, losses are recorded when probable and estimable. These losses, when incurred, have been within the range of the Company’s expectations.

Two clients each accounted for more than 10% of trade and client receivables as of December 31, 2018 and 2017. For the years ended December 31, 2018 and 2017, the Company generated $29.5 million and $24.5 million, respectively, in revenue from one client, which accounted for more than 10% of revenue for each period.

The Company is dependent upon third parties, such as Amazon Web Services, in order to meet the uptime and performance requirements of its clients.

Fair Value of Financial Instruments

The Company’s financial instruments consist of cash and cash equivalents, restricted cash, funds held in escrow, including funds in transit, trade and client receivables, prepaid and other current assets, escrow funds payable, debt, the redeemable convertible preferred stock warrant liability and the value of the common stock warrant liability. Prior to the IPO, the redeemable convertible preferred stock warrant liability was remeasured at the end of every period and was carried at fair value. Upon the IPO, the redeemable convertible preferred stock warrant was converted to a common stock warrant and is no longer remeasured. Prior to the IPO, the Company issued a common stock warrant to The Tides Foundation, which is remeasured at the end of each reporting period and carried at fair value (see Note 3 and Note 8).

The Company believes that the carrying values of the remaining financial instruments approximate their fair values.

Trade and Client Receivables and Related Allowance for Doubtful Accounts

Trade and client receivables are primarily comprised of receivables from the Company’s managed services offering and amounts receivable from clients for completed work, including amounts in transit. It also includes unbilled amounts due from clients. Trade and client receivables are recorded and stated at realizable value, net of an allowance for doubtful accounts. Credit is extended generally without collateral to the Company’s managed services client and marketplace clients with Upwork Enterprise offerings based on an initial and ongoing evaluation of their financial condition and other factors. In aggregate, gross trade receivables were $9.1 million and $8.6 million and gross client receivables were $16.0 million and $23.8 million as of December 31, 2018 and 2017, respectively.

The allowance for doubtful accounts is the Company’s estimate of the probable credit losses. The Company periodically assesses the collectability of the accounts and determines the allowance recognized by taking into consideration the aging of its receivable balances, historical write-off experience, probability of collection, and other relevant data. Trade and client receivables are written off against the allowance when management determines a balance is uncollectible and no longer actively pursues collection of the receivable.

The following table presents the changes in the allowance for doubtful accounts as of December 31, 2018, 2017 and 2016 (in thousands):



	2018			2017			2016
Allowance for doubtful accounts, beginning balance	$	1,577		$	2,473		$	2,057
Provision for doubtful accounts	4,940			2,646			3,693
Amounts written off	(3,685		)	(3,542		)	(3,277		)
Allowance for doubtful accounts, ending balance	$	2,832		$	1,577		$	2,473

Derivative Instruments

The Company uses derivative financial instruments not designated as hedges, such as foreign currency forward contracts, to minimize the short-term impact of foreign currency exchange rate fluctuations on certain foreign currency denominated assets and liabilities, as well as certain foreign currency denominated expenses, hedging the gains or losses generated by the re-measurement of significant foreign currency denominated monetary assets and liabilities. The Company does not enter into derivative instruments for speculative or trading purposes and these instruments generally have maturities within twelve months.

The foreign currency forward contracts are recorded at fair value and, when in gain positions, are reported within prepaid expenses and other current assets. When in loss positions, the foreign currency forward contracts are recorded within accrued expenses and other current liabilities in the consolidated balance sheets. Gains or losses from changes in the fair value of these foreign currency forward contracts not designated as hedging instruments are recorded in other expense, net to offset the changes in the fair value of the underlying assets or liabilities being hedged.

The notional amounts associated with the Company’s foreign currency forward contracts at December 31, 2018 and 2017 were $4.8 million and $3.6 million, respectively, none of which were designated as cash flow hedges. The carrying values of the foreign currency forward contracts approximated their fair values due to their relatively short settlement durations. The fair values of the Company’s outstanding foreign currency forward contracts not designated as hedging instruments as of December 31, 2018 and 2017 were not material. Losses on foreign currency forward contracts not designated as hedging instruments were $0.4 million for the year ended December 31, 2018, were immaterial for the year ended December 31, 2017, and were $0.5 million for the year ended December 31, 2016.

Property and Equipment

Property and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation is calculated using the straight-line method over the estimated useful lives of the related assets, which are generally three to five years. Leasehold improvements are amortized on a straight-line basis over the shorter of the remaining lease term or their estimated useful lives. Repair and maintenance costs are charged to expense as incurred.

Internal-Use Software and Platform Development Costs

The Company’s policy is to capitalize certain costs to develop its internal-use software and platform when (i) preliminary project planning is completed, (ii) the Company has committed project resourcing, and (iii) it is probable that the project will be completed and the software will be used as intended. Costs incurred for enhancements that are expected to result in additional significant functionality are also capitalized. Such costs are generally amortized on a straight-line basis over two years, beginning when the asset is ready for its intended use. Costs incurred prior to meeting these criteria, together with costs incurred for training and maintenance, are expensed as incurred. The Company capitalized costs of $4.0 million and $0.5 million for the years ended December 31, 2018 and 2017, respectively. As of December 31, 2017, since the assets had not been placed into service, amortization had not commenced. During 2018, the Company placed into service $0.6 million and recorded amortization of $0.1 million in the year ended December 31, 2018. Amortization of capitalized internal-use software is allocated to each functional expense category based on headcount. Amortization of capitalized platform development costs are included in research and development expense.

Segment Information

The Company has one reportable segment. The Company’s chief operating decision maker is its President and Chief Executive Officer, who reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance.

Goodwill, Acquired Intangible Assets, and Other Long-Lived Assets

Goodwill represents the excess of the aggregate fair value of the consideration transferred over the fair value of the net tangible and identifiable intangible assets acquired in the Elance-oDesk Combination. Goodwill is not amortized, but rather is assessed for impairment at least annually, or more frequently if events and changes in circumstances indicate that its carrying amount may not be recoverable. The Company conducts its annual assessment during the fourth quarter of each calendar year based on a single reporting unit structure. The Company may elect to utilize a qualitative assessment to determine if any events or circumstances exist, such as an adverse change in business climate or a decline in the overall industry demand, that could indicate that it would more likely than not reduce the fair value of the reporting unit below its carrying amount, including goodwill. If it is more likely than not that the fair value of the reporting unit is at or above its carrying amount, then goodwill is not considered to be impaired and no further testing is required. A two-step quantitative assessment is performed if the qualitative assessment indicates that it is more likely than not that the fair value of the reporting unit is below its carrying amount or if a qualitative assessment is not performed. The first step involves comparing the fair value of the reporting unit to its carrying value, including goodwill. If the carrying value of the reporting unit exceeds its fair value, the second step of the process is performed by comparing the carrying value of the goodwill in the reporting unit to its implied fair value. If the carrying value of the goodwill is greater than its implied fair value, an impairment charge is recognized for the excess. There has been no impairment of goodwill for any of the periods presented.

The Company’s long-lived assets consist of property and equipment and acquired identifiable, finite-lived intangible assets, namely developed technology, user relationships, trade names, and domain names. The finite-lived intangible assets are carried at cost, less accumulated amortization. The Company amortizes the finite-lived intangible assets over their estimated useful lives ranging from two to seven years based on the pattern in which the economic benefits of the intangible assets are consumed, or the straight-line method when the pattern cannot be reliably determined. The Company periodically reviews the remaining estimated useful lives of its long-lived tangible and amortizable intangible assets. If the estimated useful life assumption for any asset is changed, the remaining unamortized balance would be depreciated or amortized over the revised estimated useful life, on a prospective basis. Intangible amortization expense related to developed technology and trade names is recorded as cost of revenue. Intangible amortization expense related to user relationships and domain names is included in operating expenses.

The Company evaluates the recoverability of its long-lived assets, including finite-lived intangible assets, for possible impairment whenever events or circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of these assets is measured by comparing the carrying amounts to the future undiscounted cash flows the assets are expected to generate. If it is determined that the asset group is not recoverable, an impairment loss is recorded in the amount by which the carrying amount of the asset group exceeds the aggregate future undiscounted cash flows. When an impairment loss is recognized, the carrying amount of such assets is reduced to fair value.

For 2018, the Company conducted its goodwill impairment testing by performing the first step of the two-step impairment model. The fair value was determined by us using quoted market prices of the Company’s common stock. The Company determined that the fair value of its reporting unit exceeded the carrying value, and, as such, the Company concluded that there was no impairment of goodwill at the impairment testing date.

There was no impairment of long-lived assets in any of the periods presented.

Deferred Offering Costs

Deferred offering costs, consisting of legal, accounting, and filing fees directly relating to the Company’s IPO, were capitalized and offset against the IPO proceeds upon the completion of the offering. For the year ended December 31, 2017, the Company capitalized $0.1 million of deferred offering costs in other assets, noncurrent. Upon completion of the Company’s IPO, approximately $6.3 million of deferred offering costs were offset against the IPO proceeds in additional paid-in capital.

Revenue Recognition

The Company operates an online marketplace that enables clients to find and work with freelancers. The Company primarily generates revenue from freelancers and clients from marketplace and managed services offerings.

The Company recognizes revenue in accordance with Accounting Standards Codification (“ASC”) Topic 605, Revenue Recognition (“ASC 605”) and related authoritative guidance. Under ASC 605, revenue is recognized when the following criteria are met: (i) persuasive evidence of an arrangement exists; (ii) fees are fixed or determinable; (iii) the collection of the fees is reasonably assured; and (iv) services have been rendered. Revenue is recognized net of any taxes collected, which are subsequently remitted to governmental authorities.

The Company reports revenue in conformity with ASC 605-45, Revenue Recognition-Principal Agent Considerations. The determination of whether the Company is the principal or agent, and therefore whether to report revenue on a gross basis for the amount billed or on a net basis for the amount earned from each transaction, requires the Company to evaluate a number of indicators. The Company evaluates each separate unit of account for gross versus net as required.

The Company also reports revenue in conformity with ASC 605-50, Customer Payments and Incentives. The determination of whether the Company should characterize consideration paid to customers as costs or a reduction to revenue requires the Company to evaluate whether the consideration paid has an identifiable separable benefit to the Company and is at fair value. The Company provides certain marketing credits to clients which are treated as a reduction of revenue. The Company also enters into certain arrangements with certain financial institutions for services that require a payment to be made to certain financial institutions. These arrangements are evaluated under the guidance of ASC 605-50 to ensure classification as a reduction of revenue or cost is appropriate.

Marketplace

The Company’s marketplace revenue is derived from both its Upwork Standard offering and its Upwork Enterprise and other premium offerings.

Upwork Standard

The Company earns fees from freelancers under the Upwork Standard offering as follows:

Service fees. The Company provides freelancers access to the Upwork platform for freelancers to perform specified services agreed between freelancers and clients (“freelancer services”). Freelancers charge clients on an hourly or a milestone basis for services accessed through the Upwork platform (“freelancer billings”). The Company charges freelancers a service fee as a percentage of freelancer billings using a tiered service fee model based on cumulative lifetime billings by the freelancer to each client. For service fees charged to freelancers, the Company recognizes revenue on a net basis, as an agent, for providing access to the Upwork platform as it takes no responsibility for the freelancer services, and therefore the Company is not considered the primary obligor for the freelancer services. Additionally, freelancers and clients negotiate and agree upon the scope and the price for freelancer services directly with each other. The Company recognizes the service fee as services are rendered.

Withdrawal fees. The Company generates revenue from withdrawal fees from freelancers when the freelancers withdraw funds from their cash balances held with the Company. The Company charges a flat withdrawal fee for each withdrawal transaction and recognizes that fee as it is earned for each transaction.

Membership fees. The Company generates revenue from membership fees from freelancers. These fees are charged monthly and provide freelancers access to additional features on the Upwork platform. Membership fees are recognized over the period of the membership, which is generally monthly.

Connects fees. The Company generates revenue from connects fees from freelancers. These fees provide freelancers enhanced access to clients on the Upwork platform. These fees are recognized as services are rendered.

The Company earns fees from clients under the Upwork Standard offering as follows:

Client payment processing and administration fees. The Company generates revenue from clients for payment processing fees at the time the client is charged for the amounts due from the client. The Company charges a fee per transaction or a flat monthly payment processing fee. Per-transaction payment processing fees are recognized when the client is charged for the amount due and fees charged on a monthly basis are recognized over the month that payment processing services are provided. For client payment processing fees, the Company earns revenue on a gross basis as a principal and not net of the third-party payment processing costs incurred because the Company is considered the primary obligor for payment processing and administration services and has the latitude to set the price with clients separate and apart from the fees it pays its third-party payment processors.

Foreign currency exchange fees. The Company generates revenue from foreign currency exchange fees from clients by charging a fixed mark-up above quoted foreign currency exchange rates when the Company collects amounts denominated in foreign currency. Foreign currency exchange fees are recognized as they are earned for each payment transaction.

Upwork Payroll service fees. The Company generates revenue from Upwork Payroll service fees from clients when their freelancers are classified as employees for engagements on the Upwork platform. The client enters into an Upwork Payroll agreement with the Company, and Upwork separately contracts with unrelated third-party staffing providers who provide employment services to such clients. In such arrangements, freelancers providing freelancer services to clients become employees of third-party staffing providers. In arrangements where clients enter into Upwork Payroll agreements, the Company charges Upwork Payroll service fees to clients and does not charge service fees to the freelancers who are employees of the third-party staffing providers. Such service fees are charged as a fixed percentage of the total freelancer billings. Under an Upwork Payroll agreement, the Company provides the client access to the Upwork platform to procure and manage freelancer services, as well as access to employment services provided by the third-party staffing providers which are earned at the same time, and no allocation of fair value between these elements is required. The Company recognizes Upwork Payroll service fees revenue on a net basis as an agent of the client for providing access to employment services provided by the third-party staffing provider. The Company takes no responsibility for these employment services performed by the third party on behalf of the client. Therefore, the Company is not considered the primary obligor for these services. For freelancer services, the Company recognizes revenue on a net basis, as an agent, for providing access to the Upwork platform as it takes no responsibility for the freelancer services, and therefore the Company is not considered the primary obligor for the freelancer services. Additionally, freelancers and clients negotiate and agree upon the scope and the price for freelancer services directly with each other. The Company recognizes the Upwork payroll service fee as services are rendered by freelancers.

Upwork Enterprise and Other Premium Offerings

The Company earns fees from freelancers under Upwork Enterprise and other premium offerings as follows:

Service fees. The Company provides freelancers access to the Upwork platform to perform freelancer services for clients. The Company charges freelancers a service fee as a percentage of freelancer billings. The Company earns service fees based on a fixed percentage of freelancer billings. For service fees charged to freelancers, the Company recognizes revenue on a net basis, as an agent, for providing access to the Upwork platform as it takes no responsibility for the freelancer services, and therefore the Company is not considered the primary obligor for the freelancer services. Additionally, freelancers and clients negotiate and agree upon the scope and the price for freelancer services directly with each other. The Company recognizes the service fee as services are rendered.

The Company earns fees from clients under Upwork Enterprise and other premium offerings as follows:

Client service fees. The Company offers clients access to the Company’s platform to source freelancers in exchange for a client service fee calculated as a percentage of freelancer billings. The Company recognizes the client service fees as services are rendered by the freelancers.

Enterprise compliance service fees. The Company generates revenue from enterprise compliance service fees from clients under a compliance agreement with Upwork to determine whether a freelancer should be classified as an employee or an independent contractor based on the scope of freelancer services agreed between the client and freelancer and other factors. The Company charges enterprise compliance service fees as a percentage of freelancer billings. The Company recognizes revenue as services are rendered.

Subscription fees. The Company generates revenue from monthly or annual subscription fees from clients for subscription services that include additional service features, premium access to top talent, professional services, custom reporting, and invoicing. The revenue attribution is consistent with membership fees stated for the Company’s Upwork Standard offering.

Upwork Payroll service fees. Upwork Payroll service fees are recognized on the same basis as described under the Upwork Standard offering.

Revenue sharing arrangements. For Upwork Standard, Upwork Enterprise, and other premium offerings, the Company generates a revenue share as a percentage of the fees charged by certain financial institutions to the freelancers. The Company recognizes revenue from these arrangements as they are earned, which is generally monthly based on the contractual terms.

Managed Services

Under a managed services arrangement, the Company is responsible for providing services and engaging freelancers directly or as employees of third-party staffing providers to perform the services for clients on the Company’s behalf. The Company recognizes revenue on a gross basis for amounts charged to the client based on the Company’s determination that the Company is deemed to be the primary obligor as it takes responsibility and risk for these services completed for the client. The Company determines pricing for these services and then identifies and engages the freelancers or third-party staffing providers to fulfill the service obligation to the client. Revenue for these services is recognized as these services are rendered by the Company.

Multiple-Element Arrangements

Some of the Company’s offerings consist of multiple elements which can include a mix of services, including subscription services, employment services, compliance services, and payment processing services. Where neither vendor-specific objective evidence nor third-party evidence of selling price exists, the Company is required to use its best estimate of selling price to allocate arrangement consideration on a relative basis to each element. At the inception of arrangements which do not include subscription services, as there is no fixed consideration to be allocated, a relative fair value allocation is not required. In the instance the multiple-element arrangements include subscription services, the only fixed consideration relates to the subscription services, which is a separate unit of accounting. The fixed consideration is allocated only to the subscription services at inception, as all other fees in the arrangements are contingent on certain activities being performed as stated above.

Deferred Revenue

Deferred revenue consists of subscription, membership, and connects fees collected in advance of services being rendered.

Cost of Revenue

Cost of revenue consists primarily of the cost of payment processing fees, costs of freelancers to deliver services under the Company’s managed services offering, personnel-related costs for the Company’s services and support personnel, third-party hosting fees, and the amortization expense associated with acquired intangibles and capitalized internal-use software. The Company defines personnel-related costs as salaries, bonuses, benefits, and stock-based compensation costs for employees, and costs related to other service providers the Company engages to provide internal services to the Company.

Research and Development

Research and development expense primarily consists of personnel-related costs and third-party hosting costs related to development. Research and development costs are expensed as incurred, except to the extent that such costs are associated with platform development that qualify for capitalization.

Advertising Expense

The Company expenses advertising costs as incurred. The Company incurred $23.6 million, $14.6 million and $10.8 million in advertising expenses during the years ended December 31, 2018, 2017 and 2016, respectively.

Provision for Transaction Losses

Provision for transaction losses consists primarily of losses resulting from fraud on the platform and bad debt expense associated with the Company’s trade and client receivables balance and transaction losses expense related to chargebacks. Provision for these items represent estimates of losses based on the Company’s actual historical incurred losses and other factors.

Redeemable Convertible Preferred Stock Warrant Liability

The Company accounts for freestanding warrants to purchase shares of its redeemable convertible preferred stock as a liability as the underlying shares of convertible preferred stock are contingently redeemable and, therefore, may obligate the Company to transfer assets at some point in the future. The redeemable convertible preferred stock warrants are recorded as other liabilities, noncurrent in the consolidated balance sheets at their estimated fair values and are subject to remeasurement at each balance sheet date. Any change in fair value from remeasurement is recognized as a component of other expense, net in the consolidated statements of operations.

The Company adjusted the liability for changes in fair value through the completion of its IPO in October 2018, at which time the outstanding redeemable convertible preferred stock warrant converted to a common stock warrant and was reclassified to additional paid-in capital.

Stock-Based Compensation

The Company accounts for stock options, restricted stock units (“RSUs”) and purchase rights granted under our 2018 Employee Stock Purchase Plan (“2018 ESPP”) to employees and directors based on their estimated fair value on the date of grant. The fair value of each stock option and purchase rights granted under the 2018 ESPP is estimated using the Black-Scholes valuation model. The model requires the Company to make a number of assumptions, including the value of the Company’s common stock, expected volatility, expected term, risk-free interest rate, and expected dividends. The Company evaluates the assumptions used to value option awards upon each grant of stock options. The fair value of RSUs awarded to employees is based on the closing price of the Company’s common stock, as reported on The Nasdaq Global Select Market on the date of grant.

The Company generally recognizes stock-based compensation expense for stock options and RSUs on a straight-line basis over the vesting term. For the performance based award granted to the Chief Executive Officer, expense is recognized over a graded vesting attribution schedule (see Note 10). Stock-based compensation for purchase rights granted under the 2018 ESPP is recognized over the offering period. Prior to the adoption of Accounting Standards Update No. 2016-09 (“ASU 2016-09”) on January 1, 2018, stock-based compensation expense was recognized only for those awards expected to vest. The Company estimated forfeitures based on historical rates of forfeitures of awards adjusted to reflect future changes in facts and circumstances, if any, and revised its estimated forfeiture rate if actual forfeitures differed from initial estimates. Subsequent to the adoption, the Company accounts for forfeitures as they occur.

The Company also grants stock options to non-employee service providers. For these stock options, the Company believes the fair value of the stock option on the date of grant is more reliably measurable than the fair value of the services rendered. Therefore, the Company estimates the fair value of nonemployee stock options using the Black-Scholes valuation model with assumptions as discussed in Note 10. The estimated fair value of nonemployee stock options is remeasured over the vesting period as it is being earned, and the expense is recognized on a straight-line basis over the period during which services are rendered.

Foreign Currency

The functional currency of the Company and its subsidiaries is the U.S. dollar. Transactions with users denominated in currencies other than the U.S. dollar are remeasured at the exchange rate in effect on the date of the transaction. At the end of each reporting period, monetary assets and liabilities are remeasured using exchange rates in effect at the balance sheet date. Foreign currency transaction gains and losses are included in other expense, net in the consolidated statements of operations. The Company recorded net foreign currency transaction losses of $0.4 million and $0.5 million for the years ended December 31, 2018 and 2016, respectively. Foreign currency transaction gains and losses for the year ended December 31, 2017 were immaterial.

Comprehensive Loss

Comprehensive loss is equal to the net loss for all periods presented. Accordingly, the consolidated statements of comprehensive loss have been omitted from the consolidated financial statements.

Income Taxes

The Company accounts for income taxes in accordance with the liability method. Under the liability method, deferred assets and liabilities are recognized based upon anticipated future tax consequences attributable to differences between financial statement carrying amounts of assets and liabilities and their respective tax bases. The provision for income taxes is comprised of the current tax liability and the change in deferred tax assets and liabilities. The Company establishes a valuation allowance to the extent that it is more likely than not that deferred tax assets will not be recoverable against future taxable income.

Deferred tax assets and liabilities are measured using the enacted tax rates that will be in effect for the years in which those tax assets are expected to be realized or settled. The Company regularly assesses the likelihood that its deferred tax assets will be realized from recoverable income taxes or recovered from future taxable income based on the realization criteria set forth in the relevant authoritative guidance. To the extent that the Company believes any amounts are not more likely than not to be realized, the Company records a valuation allowance to reduce its deferred tax assets. The realization of deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. Accordingly, the net deferred tax assets have been fully offset by a valuation allowance. If the Company subsequently realizes deferred tax assets that were previously determined to be unrealizable, the respective valuation allowance would be reversed, resulting in an adjustment to earnings in the period such determination is made.

In addition, the calculation of tax liabilities involved dealing with uncertainties in the application of complex tax regulations. The Company recognized potential liabilities based on its estimate of whether, and the extent to which, additional taxes will be due. The Company accounts for uncertain tax positions in accordance with the relevant guidance, which prescribes a recognition threshold and measurement approach for uncertain tax positions taken or expected to be taken in a company’s income tax return, and also provides guidance on recognition, classification, interest and penalties, accounting in interim periods, disclosure, and transition. The guidance utilized a two-step approach for evaluation uncertain tax positions. Step one, Recognition, requires a company to determine if the weight of available evidence indicates a tax position is more likely than not to be sustained upon audit. Step two, Measurement, is based on the largest amount of benefit, which is more likely than not to be realized on ultimate settlement. A liability is reported for unrecognized tax benefits resulting from uncertain tax positions taken or expected to be taken in a tax return. Any interest and penalties related to unrecognized tax benefits are recorded as income tax expense.

Net Loss per Share Attributable to Common Stockholders

Prior to its IPO, the Company followed the two-class method when computing net loss per share as the Company had issued shares that met the definition of participating securities. The two-class method determined net loss per share for each class of common stock and participating securities according to accumulated and participation rights in undistributed earnings. The two-class method required income available to common stockholders for the period to be allocated between common stock and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. The Company’s redeemable convertible preferred stock contractually entitled the holders of such shares to participate in dividends, but did not contractually require the holders of such shares to participate in losses of the Company. Accordingly, the two-class method did not apply for periods in which the Company reported a net loss or a net loss attributable to common stockholders

Upon the closing of the IPO in October 2018, all outstanding shares of redeemable convertible preferred stock were converted into shares of common stock. As such, the two-class method is no longer applicable.

Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of common shares outstanding for the period. Diluted net loss attributable to common stockholders is computed by adjusting net loss attributable to common stockholders to reallocate undistributed earnings based on the potential impact of dilutive securities, including outstanding common stock options, convertible preferred stock and warrants to purchase common stock and convertible preferred stock. For periods in which the Company has reported net losses, diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders, because dilutive common shares are not assumed to have been issued if their effect is anti-dilutive.

Recent Accounting Pronouncements Not Yet Adopted

As an “emerging growth company,” the Jumpstart Our Business Startups Act (“JOBS Act”) allows the Company to delay adoption of new or revised accounting pronouncements applicable to public companies until such pronouncements are made applicable to private companies. The Company has elected to use this extended transition period under the JOBS Act. The adoption dates discussed below reflect this election.

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (“ASC 606”). ASC 606 supersedes the revenue recognition requirements in ASC 605, and requires the recognition of revenue when promised goods or services are transferred to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASC 606 also includes Subtopic 340-40, Other Assets and Deferred Costs—Contracts with Customers (“Subtopic 340-40” and together with ASC 606, the “new revenue standard”), which requires the deferral of incremental costs of obtaining a contract with a customer. In August 2015, the FASB deferred the effective date for annual reporting periods beginning after December 15, 2017. In 2016, the FASB issued amendments on this guidance with the same effective date and transition guidance. The new revenue standard may be applied retrospectively to each prior period presented or retrospectively with the cumulative effect recognized as of the date of adoption.

The Company is required to adopt the new revenue standard for the year ending December 31, 2019. Interim reporting under ASC 606 will not be required until 2020. To date, the Company has established an implementation team and is in the process of evaluating the impact of the new revenue standard on its accounting policies, processes, and system requirements. Furthermore, the Company has made and will continue to make investments in systems to enable timely and accurate reporting under the new revenue standard.

The Company is continuing to evaluate the adoption method and the potential impact that the implementation of this standard will have on its consolidated financial statements, specifically related to the following items:


•	identification of performance obligations;


•	principal agent considerations;


•	whether the discounts offered under the Company’s tiered pricing program for freelancer service fee result in a “material right” as that term is defined in ASC 606;


•	whether costs to obtain a contract with a customer will be capitalized or expensed;


•	timing of revenue recognition;


•	method of adoption; and


•	revenue disclosures which are expected to expand and may require judgment in certain areas.

In February 2016, FASB issued ASU No. 2016-02, Leases (Topic 842), related to how an entity should recognize lease assets and lease liabilities. The guidance specifies that an entity that is a lessee under lease agreements should recognize lease assets and lease liabilities for those leases classified as operating leases under previous FASB guidance. Accounting for leases by lessors is largely unchanged under the new guidance. In 2018, the FASB also approved an amendment that would permit the option to adopt the new standard prospectively as of the effective date, without adjusting comparative periods presented. The new standard becomes effective for the Company for the year ending on December 31, 2020. The Company anticipates the effect of adopting this update will be recognizing right-of-use assets and corresponding lease liabilities for leases where we are the lessee, primarily comprised of leases for facilities. The Company is continuing to assess all implications of this new guidance on its consolidated financial statements.

In June 2016, the FASB issued ASU 2016–13, Financial Instruments-Credit Losses (“Topic 326”). The standard changes the methodology for measuring credit losses on financial instruments and the timing of when such losses are recorded. In November 2018, the FASB issued ASU 2018-19, Codification Improvements to Topic 326, to clarify that receivables arising from operating leases are within the scope of lease accounting standards. The guidance is effective for the Company for fiscal year 2021 with early adoption permitted. The standard requires a modified retrospective method of adoption. The Company has not yet evaluated the impact of these standard updates on its consolidated financial statements and related disclosures.

In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payment, to clarify how certain cash receipts and payments are presented and classified in the statement of cash flows. The new guidance becomes effective for the Company for the year ending December 31, 2019, although early adoption is permitted. The Company is currently evaluating the impact of adopting this new guidance on its consolidated financial statements.

In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash, that will require that the amounts generally described as restricted cash and restricted cash equivalents would be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period amounts shown on the statement of cash flows. The new guidance also requires certain disclosures to supplement the statement of cash flows. The guidance becomes effective for the Company for the year ending on December 31, 2019, although early adoption is permitted. The Company is currently evaluating the effect this guidance will have on its consolidated financial statements, but does not expect it to have a significant impact on its consolidated financial statements and related disclosures.

In January 2017, the FASB issued ASU No. 2017-04, Intangibles—Goodwill and Others (Topic 350): Simplifying the Test for Goodwill Impairment. ASU No. 2017-04 eliminates Step 2 from the goodwill impairment test, which measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. Under ASU No. 2017-04, an entity should perform its annual or interim goodwill impairment test by comparing the fair value of the reporting unit with its carrying amount and recognize an impairment loss for the amount by which the carrying amount exceeds the reporting unit’s fair value, with the loss not exceeding the total amount of goodwill allocated to that reporting unit. The guidance becomes effective for the Company on a prospective basis for its annual or any interim goodwill impairment tests during the year ending on December 31, 2021, although early adoption is permitted. The Company is currently evaluating the impact of adopting this new guidance on its consolidated financial statements.

In August 2017, the FASB issued ASU No. 2017–12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities, which expands and refines hedge accounting for both financial and non–financial risk components, aligns the recognition and presentation of the effects of hedging instruments and hedge items in the financial statements, and includes certain targeted improvements to ease the application of current guidance related to the assessment of hedge effectiveness. In addition, in October 2018, the FASB issued ASU No. 2018–16, Derivatives and Hedging (Topic 815), which amends Topic 815 to add the overnight index swap (OIS) rate based on the secured overnight financing rate as a fifth U.S. benchmark interest rate. These standards are effective for the Company for fiscal years beginning after December 15, 2019. The Company has not yet evaluated the impact of these standards on its consolidated financial statements and related disclosures.

In June 2018, the FASB issued ASU No. 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. ASU No. 2018-07 expands the scope of Topic 718, Compensation-Stock Compensation to include share-based payment transactions for acquiring goods and services from non-employees. These awards are measured at the grant-date fair value of the equity instruments that an entity is obligated to issue when the good has been delivered or the service has been rendered and any other conditions necessary to earn the right to benefit from the instruments have been satisfied. The guidance is effective for the Company for the fiscal year ending on December 31, 2020, although early adoption is permitted but not earlier than the Company’s adoption of ASC 606, and the guidance requires a modified retrospective application to awards that have not been settled as of the adoption date. The Company has not yet evaluated the impact of this standard on its consolidated financial statements and related disclosures.

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement, which modifies the disclosure requirements on fair value measurements. ASU No. 2018-13 is effective for the Company for the fiscal year ending on December 31, 2021, although early adoption is permitted. The Company has not yet evaluated the impact of this standard on its consolidated financial statements and related disclosures.

In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. ASU 2018-15 aligns the requirements for capitalizing implementation costs in a cloud computing arrangement service contract with the requirements for capitalizing implementation costs incurred for an internal-use software license. ASU No. 2018-15 is effective for the Company for the fiscal year ending on December 31, 2021, although early adoption is permitted. The Company has not yet evaluated the impact of this standard on its consolidated financial statements and related disclosures.

Recently Adopted Accounting Pronouncements

In March 2016, the FASB issued ASU 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The Company adopted this standard as of January 1, 2018. ASU 2016-09 eliminates the requirement to delay the recognition of excess tax benefits until they reduce current taxes payable. Under this standard, previously unrecognized excess tax benefits shall be recognized on a modified retrospective basis. ASU No. 2016-09 also requires excess tax benefits and deficiencies to be recognized prospectively in the Company’s provision for income taxes rather than additional paid-in capital. Additionally, the Company elected to account for forfeitures as they occur rather than estimate expected forfeiture using a modified retrospective transition method. Finally, ASU No. 2016-09 requires excess tax benefits to be presented as a component of operating cash flows rather than financing cash flows. The Company elected to adopt this requirement prospectively and accordingly, prior periods have not been adjusted. The adoption of this standard was immaterial to the Company’s consolidated financial statements as of and for the year ended December 31, 2018.

In May 2017, the FASB issued ASU 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting, which provides guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in the ASU. The Company adopted this standard as of January 1, 2018. The adoption of this standard had no impact on the Company’s consolidated financial statements as of and for the year ended December 31, 2018.

Fair Value Measurements

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurements

Prior to its IPO, the Company measured its redeemable convertible preferred stock warrant liability at fair value on a recurring basis. The Company recorded $6.1 million, $0.1 million, and $0.1 million related to the revaluation of its redeemable convertible preferred stock warrant liability, which is included in other expense, net in the Company’s consolidated statements of operations for the years ended December 31, 2018, 2017, and 2016, respectively. Upon the closing of the IPO in October 2018, the redeemable convertible preferred stock warrant converted to a common stock warrant. As such, the Company reclassified its redeemable convertible preferred stock warrant liability to additional paid in capital.

The Company defines fair value as the exchange price that would be received from sale of an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance describes three levels of inputs that may be used to measure fair value:


•	Level I—Observable inputs that reflect unadjusted quoted prices for identical assets or liabilities in active markets;


•	Level II—Observable inputs other than Level I prices, such as unadjusted quoted prices for similar assets or liabilities in active markets, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; and


•	Level III—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. These inputs are based on the Company’s own assumptions used to measure assets and liabilities at fair value and require significant management judgment or estimation.

The categorization of a financial instrument within the fair value hierarchy is based upon the lowest level of input that is significant to its fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the assets or liability.

The Company’s financial instruments that are carried at fair value consist of Level I assets as of December 31, 2018 and Level III liabilities as of December 31, 2017. The Company’s redeemable convertible preferred stock warrant liability was classified within Level III because the warrants were valued using a Black-Scholes valuation model, for which some inputs are unobservable in the market. The valuation methodology and underlying assumptions are discussed further in Note 8.

The following tables set forth the fair value of the Company’s financial assets and liabilities measured at fair value on a recurring basis based on the three-tier fair value hierarchy (in thousands):



	December 31, 2018
	Level I		Level II		Level III		Total
Financial Assets:
Cash Equivalents
Money market funds	$	117,138	$	—	$	—	$	117,138
Total financial assets	$	117,138	$	—	$	—	$	117,138



	December 31, 2017
	Level I		Level II		Level III		Total
Financial Liabilities:
Redeemable convertible preferred stock warrant liability	$	—	$	—	$	1,104	$	1,104
Total financial liabilities	$	—	$	—	$	1,104	$	1,104

The following table sets forth a summary of the changes in the fair value of the redeemable convertible preferred stock warrant liability (in thousands):



Fair value at January 1, 2016	$	1,016
Change in fair value	114
Fair value at December 31, 2016	1,130
Change in fair value	118
Reclassification to redeemable convertible preferred stock due to warrant exercise	(144		)
Fair value at December 31, 2017	1,104
Change in fair value	6,056
Conversion to common stock warrant in connection with the initial public offering	(7,160		)
Fair value at December 31, 2018	$	—

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Balance Sheet Components

12 Months Ended

Dec. 31, 2018

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Components

Property and Equipment, Net

Property and equipment, net consisted of the following as of December 31, 2018 and 2017 (in thousands):



	2018			2017
Computer equipment and software	$	3,189		$	5,385
Internal-use software and platform development costs	6,287			2,318
Leasehold improvements	5,783			2,189
Office furniture and fixtures	2,545			1,550
Total property and equipment	17,804			11,442
Less: Accumulated depreciation	(6,989		)	(7,928		)
Property and equipment, net	$	10,815		$	3,514

Depreciation expense related to property and equipment was $2.2 million, $1.5 million, and $1.8 million for the years ended December 31, 2018, 2017, and 2016, respectively.

The Company capitalized $4.0 million and $0.5 million of internal-use software and platform development costs during the years ended December 31, 2018 and 2017, respectively. The Company did not capitalize any internal-use software and platform development costs for the year ended December 31, 2016. Amortization expense related to the capitalized internal-use software and platform development costs was $0.1 million for the year ended December 31, 2018. There was no amortization expense for the year ended December 31, 2017 related to the internal-use software and platform development costs as the underlying assets had not been placed into service as of December 31, 2017. Amortization expense related to internal-use software and platform development costs was $1.0 million for the year ended December 31, 2016.

Intangible Assets, Net

All of the Company’s identifiable intangible assets were acquired in March 2014 from the Elance-oDesk Combination. Intangible assets, net consisted of the following (in thousands):



	As of December 31, 2018
	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Trade names	$	2,293	$	2,293	$	—
User relationships	18,678		12,674		6,004
Developed technology	10,356		10,356		—
Domain names	529		529		—
Total	$	31,856	$	25,852	$	6,004



	As of December 31, 2017
	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Trade names	$	2,293	$	2,293	$	—
User relationships	18,678		10,006		8,672
Developed technology	10,356		10,356		—
Domain names	529		529		—
Total	$	31,856	$	23,184	$	8,672

Total amortization expense of intangible assets was $2.7 million and $2.7 million for the years ended December 31, 2018 and 2017, respectively. Amortization expense was included in general and administrative expenses. As of December 31, 2018, the remaining useful life for user relationships was 2.3 years.

Total amortization expense of intangible assets was $5.7 million for the year ended December 31, 2016, of which $2.9 million was included in cost of revenue related to developed technology and trade names. The remaining carrying amount of $2.6 million for developed technology was accelerated in 2016 when the Elance platform was decommissioned. Amortization for the user relationships of $2.7 million was included in general and administrative expenses for the year ended December 31, 2016.

As of December 31, 2018, the estimated future amortization expense for the acquired intangible assets is as follows (in thousands):



Year Ended December 31,	Estimated Amortization Expense
2019	$	2,668
2020	2,668
2021	668
Total	$	6,004

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following as of December 31, 2018 and 2017 (in thousands):



	2018		2017
Accrued compensation and related benefits	$	9,314	$	8,399
Accrued freelancer costs	2,465		134
Accrued indirect taxes	1,630		1,861
Accrued vendor expenses	6,002		4,198
Accrued payment processing fees	715		593
Other	822		845
Total accrued expenses and other current liabilities	$	20,948	$	16,030

Commitments and Contingencies

12 Months Ended

Dec. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Operating Leases

The Company leases office space under four non-cancellable operating lease agreements, which expire from 2019 through 2025. The terms of the office leases contain rent escalation clauses, rent holidays, or tenant improvement allowances. The Company recognizes rent expense on a straight-line basis over the non-cancellable lease term and records the difference between cash payments and the recognition of rent expense as a deferred rent liability. Where leases contain escalation clauses, rent holidays, or tenant improvement allowances, the Company applies them in the determination of straight-line rent expense over the lease term. In September 2015, the Company entered into an agreement to sublease a portion of its office space in San Francisco and recognized sublease income of $0.9 million in each of the years ended December 31, 2017 and 2016. The sublease agreement was terminated in November 2017.

In 2018, the Company entered into an agreement to extend its non-cancellable operating lease for its San Francisco office through 2024. From September 1, 2019 through August 31, 2024, total minimum lease payments under the lease agreement are $15.7 million, with lease payments ranging from $1.0 million to $2.2 million per year from 2019 to 2024.

Also in 2018, the Company entered into an agreement for a non-cancellable operating lease for new office space in Chicago through October 2024. In December 2018, the Company entered into an amendment (“First Amendment”) extending the term of the original lease from October 2024 to April 2025 and to lease additional office space to accommodate continued headcount growth. From June 1, 2019 through April 30, 2025, total minimum lease payments under the original lease agreement and the First Amendment are $10.3 million, with lease payments ranging from $0.5 million to $2.0 million per year from 2019 to 2025. The Company moved its Chicago-based operations to this new office space in January 2019. In connection with this move, the Company entered into a sublease in December 2018 providing for the sublease of the office space in Chicago that the Company occupied prior to the execution of this new operating lease. The expected sublease payments from the December 2018 agreement are reflected in the aggregate minimum lease payment table below.

As of December 31, 2018, future aggregate minimum lease payments under the non-cancellable operating leases were as follows (in thousands):



Year Ended December 31,	Minimum Lease Payments
2019	$	3,569
2020	4,683
2021	4,914
2022	5,052
2023	5,194
Thereafter	4,890
Less: rental payments from subleases	(363		)
Total	$	27,939

Rent expense was $4.2 million, $3.7 million and $3.6 million for the years ended December 31, 2018, 2017 and 2016, respectively.

Letters of Credit

In conjunction with the operating lease agreements, the Company had three and two irrevocable letters of credit outstanding in the aggregate amount of $0.8 million as of December 31, 2018 and 2017. The letters of credit are collateralized by restricted cash in the same amount and expire in 2019. No amounts had been drawn against these letters of credit as of December 31, 2018 and 2017.

Contingencies

The Company accrues contingent liabilities when it is probable that future expenditures will be made and such expenditures can be reasonably estimated. From time to time in the normal course of business, various claims and litigation have been asserted or commenced. Due to uncertainties inherent in litigation and other claims the Company can give no assurance that it will prevail in any such matters, which could subject the Company to significant liability or damages. Any claims or litigation could have an adverse effect on the Company’s business, financial position, results of operations or cash flows in or following the period that claims or litigation are resolved.

On February 8, 2016, a company filed suit against the Company alleging that the Company’s trademark “Upwork” infringed on the plaintiff’s prior mark. The plaintiff further alleged that the Company had wrongfully profited from and harmed it by the use of “Upwork” to market the Company since the Company began using the name in May 2015. The Company filed counterclaims alleging the plaintiff infringed its rights in other jurisdictions. The Company accrued $1.1 million for settlement costs as of December 31, 2016 and settled the lawsuit in April 2017.

As of December 31, 2018 and 2017, the Company was not a party to any material legal proceedings or claims, nor is the Company aware of any pending or threatened litigation or claims that could reasonably be expected to have a material adverse effect on its business, operating results, cash flows, or financial condition. Accordingly, the Company has determined that the existence of a material loss as of this date is neither probable nor reasonably possible.

Indemnification

The Company has indemnification agreements with its officers, directors, and certain key employees to indemnify them while they are serving in good faith in their respective positions. In the ordinary course of business, the Company enters into contractual arrangements under which it agrees to provide indemnification of varying scope and terms to vendors and other parties, including, but not limited to, losses arising out of the Company’s breach of such agreements. In addition, subject to the terms of the applicable agreement, as part of the Company’s Upwork Enterprise offering, the Company indemnifies clients that subscribe to worker classification services for losses arising from worker misclassification and intellectual property claims made by third parties relating to the use of the Company’s platform. It is not possible to determine the maximum potential loss under these indemnification provisions due to the Company’s limited history of prior indemnification claims and the facts and circumstances involved in each particular provision.

Debt

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Debt

The following table presents the carrying value of the Company’s debt as of December 31, 2018 and 2017 (in thousands):



	2018			2017
First term loan—18 months of interest-only payments ending in March 2019 followed by 36 equal monthly installments of principal plus interest, maturing March 2022; interest at Prime plus 0.25% per annum	$	15,000		$	15,000
Second term loan—11 months of interest-only payments ending in October 2018 followed by 47 equal monthly installments of principal plus interest, maturing September 2022. As of September 30, 2018, the Company achieved trailing six-month EBITDA of at least $1.0 million; as a result, the interest-only repayment period extended to March 2019, followed by 42 equal monthly installments of principal plus interest; bears interest at Prime plus 5.25% per annum. As a result of the Company's IPO, the interest rate was reduced to Prime plus 0.25% per annum	9,000			9,000
Line of credit—interest at Prime with accrued interest due monthly; matures September 2020	—			10,000
Total debt	24,000			34,000
Less: Unamortized debt discount issuance costs	(90		)	(167		)
Balance	23,910			33,833
Debt, current	(5,671		)	(10,342		)
Debt, noncurrent	$	18,239		$	23,491
Weighted-average interest rate	6.89		%	5.93		%

In September 2017, the Company entered into a Loan and Security Agreement (the “Loan Agreement”), which was subsequently amended in November 2017 and September 2018. The Loan Agreement consisted initially of a term loan (the “First Term Loan”) of $15.0 million and a $15.0 million revolving line of credit based on eligible trade and client accounts receivable, for an aggregate facility amount of up to $30.0 million. However, upon the Company achieving adjusted net revenue of at least $49.0 million in a trailing three-month period on or before June 30, 2018, the revolving line of credit increased to $25.0 million with a corresponding increase to the aggregate facility amount to up to $40.0 million. The Loan Agreement was amended in November 2017 to include a second term loan of $9.0 million (the “Second Term Loan,” and together with the First Term Loan, the “Term Loans”), which, in turn, increased the aggregate maximum amount of the facility up to $49.0 million. The Company incurred debt issuance costs of $0.2 million, which was primarily classified as a deduction to the long-term portion of the Term Loans. In November 2017, the Company drew down $10.0 million under the revolving line of credit and $9.0 million under the Term Loans. The Company has granted its lender first-priority liens against substantially all of its assets, as collateral, excluding the Company’s intellectual property (but including proceeds therefrom) and the funds and assets held by the Company’s subsidiary, Upwork Escrow Inc. The Company has also agreed to a negative pledge on its intellectual property. The Loan Agreement is also subject to the Company maintaining an adjusted quick ratio of 1.30 and achieving minimum EBITDA levels over trailing periods ranging from three to twelve months. The Loan Agreement also includes a restrictive covenant on dividend payments other than dividends paid solely in common stock. The Company used $19.0 million of its borrowings to repurchase shares of its redeemable convertible preferred stock in 2017 (see Note 7).

In September 2018, the Company entered into a second amendment (the “Second Amendment”) to the Loan Agreement which expanded the types of eligible trade and client accounts receivable considered for the determination of the borrowing base of the revolving line of credit. The Second Amendment also provided for a reduction in the interest rate for the Second Term Loan, from prime plus 5.25% to prime plus 0.25%, from and after the occurrence of an initial public offering by the Company with net proceeds of more than $50.0 million; this reduction became effective following the completion of the Company’s IPO in October 2018. To the extent the Company has not yet collected funds for hourly billings from clients which are in-transit due to timing differences in receipt of cash from clients, the Company from time to time utilizes the revolving line of credit to satisfy escrow funding requirements. In September 2018, the Company drew down $15.0 million under the revolving line of credit for such purpose and repaid the borrowings in full in the first week of October 2018 when the Company collected funds from clients. In October 2018, the Company used part of the net proceeds from the IPO to repay $10.0 million of indebtedness owed under the revolving line of credit.

The amortization expense related to the debt discount was immaterial for the years ended December 31, 2018, 2017, and 2016. The Company was in compliance with all financial-related covenants under the Loan Agreement as of December 31, 2018 and 2017.

Future maturities of principal payments, excluding potential early payments, as of December 31, 2018, were expected to be as follows (in thousands):



Year Ended December 31,	Principal Payments
2019	$	5,679
2020	7,571
2021	7,571
2022	3,179
Total	$	24,000

Redeemable Convertible Preferred Stock

12 Months Ended

Dec. 31, 2018

Temporary Equity Disclosure [Abstract]

Redeemable Convertible Preferred Stock

The Company completed its IPO in October 2018, in which the Company issued and sold 7,840,908 shares of common stock at a public offering price of $15.00 per share, before deducting underwriting discounts and commissions and offering expenses payable by the Company. As a result, all of the Company’s 61,279,079 shares of outstanding redeemable convertible preferred stock automatically converted into shares of common stock on a one-for-one basis. Therefore, there were no issued or outstanding shares of redeemable convertible preferred stock as of December 31, 2018.

Redeemable convertible preferred stock as of December 31, 2017 consisted of the following (in thousands, except share data):



	Shares Authorized	Shares Issued and Outstanding	Net Carrying Value		Aggregate Liquidation Preference
Series A-1	10,141,345	9,142,770	$	72,181	$	91,427
Series A-2	60,000,000	47,124,931	65,853		5
Series B-1	5,854,982	4,866,360	27,628		27,787
Series B-2	145,018	145,018	824		828
Total redeemable convertible preferred stock	76,141,345	61,279,079	$	166,486	$	120,047

Shares of redeemable convertible preferred stock were not mandatorily redeemable. However, a liquidation or winding up of the Company, a greater than 50% change in control, or a sale of substantially all of the Company’s assets would constitute a redemption event that is outside of the Company’s control. As such, all shares of redeemable convertible preferred stock were presented outside of permanent equity. The Company did not adjust the carrying values of the redeemable convertible preferred stock to the deemed liquidation values of such shares since a liquidation event was not probable as of December 31, 2017. No subsequent adjustments to increase or decrease the carrying values were made between December 31, 2017 and the date of the Company’s IPO. As a result of the Elance-oDesk Combination, holders of preferred stock of Elance and holders of preferred stock of oDesk each received as consideration for such shares a combination of shares of Series A-1 and Series A-2 redeemable convertible preferred stock. As a result, no stockholder held shares of Series A-1 redeemable convertible preferred stock without also holding shares of Series A-2 redeemable convertible preferred stock, nor did any stockholder hold shares of Series A-2 redeemable convertible preferred stock without also holding shares of Series A-1 redeemable convertible preferred stock. The rights, privileges, and preferences of the Series A-1, Series A-2, Series B-1, and Series B-2 redeemable convertible preferred stock (“Preferred Stock”) were as follows:

Dividends

Holders of the Series A-1, Series A-2, Series B-1, and Series B-2 redeemable convertible preferred stock were each entitled to non-cumulative dividends of $0.80, $0.000008, $0.4568, and $0.4568 per share, respectively. Dividends on the Preferred Stock were payable only when, and if, declared by the board of directors. No dividends on the Preferred Stock were declared by the Company’s board of directors, or were paid, as of December 31, 2017 and as of the date of the Company’s IPO.

Voting Rights

The holders of each share of Preferred Stock were entitled to the number of votes equal to the number of shares of common stock into which their respective shares were convertible, provided, however, that the holders of Series B-2 redeemable convertible preferred stock, or common stock issued upon conversion thereof, were not entitled to cast votes in connection with the election of members of the board of directors. The holders of Preferred Stock had certain protective provisions so long as an aggregate of 15.1 million shares of Preferred Stock were outstanding. Under these provisions, the Company could not, without the approval of greater than 50% of the then-outstanding shares of Preferred Stock (i) alter or change the rights, powers, or preferences of the Preferred Stock set forth in the Company’s certificate of incorporation or bylaws, (ii) authorize or create any new class of stock having rights, powers or preferences that were senior to or on parity with any series of Preferred Stock, or obligate itself to authorize or create any security convertible into or exercisable for such class of stock, (iii) redeem or repurchase any shares of common stock or Preferred Stock (other than shares subject to the Company’s right of repurchase, through the exercise of any right of first refusal, or otherwise approved by the board of directors), (iv) declare or pay a dividend or otherwise make a distribution to holders of Preferred Stock or common stock (other than a dividend on the common stock payable solely in shares of common stock or a repurchase approved by the board of directors), (v) voluntarily liquidate, dissolve, or wind-up the business or effect a deemed liquidation event (as defined in the certificate of incorporation), or (vi) increase or decrease the authorized number of directors constituting the board of directors.

In addition, so long as any shares of any series of Preferred Stock were outstanding, the Company could not, without the approval of greater than 50% of the then-outstanding shares of such series of Preferred Stock, alter or change the rights, powers, or preferences of such series of Preferred Stock set forth in the Company’s certificate of incorporation or bylaws in a way that adversely affected such series of Preferred Stock in a manner different from other series of Preferred Stock (other than (a) the authorization, creation, or issuance of any new class or series of capital stock having rights, powers, or preferences that were senior to, on parity with, or junior to any series of Preferred Stock and (b) an amendment or other change of the rights, powers, or preferences of any series of preferred stock that was proportional to the amendments or other changes similarly made to other series of Preferred Stock that had a similar right, power, or preference).

Conversion

The holders of each share of Preferred Stock had the option to convert each share of Preferred Stock at any time into a number of shares of common stock determined by dividing the original issue price per share by the then-current conversion price for such series. The original issue prices per share for the Series A-1, Series A-2, Series B-1, and Series B-2 redeemable convertible preferred stock were $10.00, $0.0001, $5.71, and $5.71, respectively, and, subject to adjustments for certain dilutive issuances, splits, and combinations, and other recapitalizations or reorganizations, the conversion price for each series of Preferred Stock was equal to the original issue price for such series. In the event that any holder of Series A-1 or Series A-2 redeemable convertible preferred stock elected to voluntarily convert shares of such Preferred Stock into shares of common stock, the election was deemed to be an election of such holder to convert shares of Series A-1 and Series A-2 redeemable convertible preferred stock held by such holder into shares of common stock at the same ratio and in the same proportions. In addition, the Preferred Stock would automatically be converted into common stock upon the earlier of (i) the written consent of the holders of at least a majority of the then-outstanding shares of Preferred Stock, voting together as a single class on an as-converted basis or (ii) an IPO that resulted in aggregate gross proceeds to the Company of at least $50.0 million. As of December 31, 2017, the conversion ratio was 1:1 for each series of Preferred Stock.

Liquidation Preference

In the event of liquidation, dissolution, or winding up or any deemed liquidation event of the Company, the holders of Preferred Stock were entitled to receive the greater of (i) their full preferential amounts plus any declared but unpaid dividends and (ii) such amount per share as would have been payable had all shares of such series of Preferred Stock been converted into common stock, prior to any distribution to the holders of common stock. If the assets available for distribution were insufficient to pay such amounts, then the entire assets available for distribution would have been distributed ratably among the holders of Preferred Stock in proportion to the full amount each holder was otherwise entitled to receive. After payment to the holders of Preferred Stock of their full preferential amounts specified above, the Company’s remaining assets available for distribution to stockholders would be distributed among the holders of common stock pro rata based upon the number of shares of common stock held by each holder. The preferential amounts per share of the Series A-1, Series A-2, Series B-1, and Series B-2 redeemable convertible preferred stock were $10.00, $0.0001, $5.71, and $5.71, respectively, as of December 31, 2017.

A deemed liquidation event would be deemed to have occurred upon (a) a merger or consolidation of the Company into another entity (except where the merger or combination results in the holders of the Company’s capital stock prior to the merger or consolidation continuing to hold at least 50% of the voting power of the surviving or acquiring entity) or (b) a sale, lease, transfer, exclusive license, or other disposition, in a single transaction or a series of related transactions, of all or substantially all of the Company’s assets (or in the case of an exclusive license, of all or substantially all of the Company’s intellectual property). The holders of Preferred Stock could waive the treatment of any transaction as a deemed liquidation event by a vote of the holders of a majority of the then-outstanding shares of Preferred Stock.

Redemption

The holders of Preferred Stock had no voluntary rights to redeem shares.

Repurchase of Redeemable Convertible Preferred Stock in Connection with Secondary Market Transaction

In November 2017, the Company’s board of directors approved the repurchase of 874,069 shares of Series A-1 redeemable convertible preferred stock, 3,151,858 shares of Series A-2 redeemable convertible preferred stock, and 242,562 shares of Series B-1 redeemable convertible preferred stock, from one stockholder at the purchase price of $4.50 per share, for a total consideration of $19.2 million, which exceeded the carrying value of $12.7 million on the date of repurchase. The redeemable convertible preferred stock repurchased was retired immediately thereafter. The repurchase price in excess of the carrying value of redeemable convertible preferred stock of $6.5 million was recorded as a reduction to additional paid-in capital, while the carrying value of the shares repurchased was recorded as a reduction to redeemable convertible preferred stock. For the computation of earnings per share for the year ended December 31, 2017, the repurchase price in excess of the carrying value of the redeemable convertible preferred stock of $6.5 million is reflected as an increase to net loss attributable to common stockholders (see Note 11).

Preferred and Common Stock Warrants

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Preferred and Common Stock Warrants

Redeemable Convertible Preferred Stock Warrants

As a result of the Elance-oDesk Combination, a redeemable convertible preferred stock warrant that was originally issued by Elance prior to the Elance-oDesk Combination became exercisable to purchase up to 26,000 and 57,181 shares of the Company’s Series A-1 and Series A-2 redeemable convertible preferred stock, respectively, at an exercise price of $3.13 per share. In June 2017, the warrant was exercised in full for cash.

Further, as a result of the Elance-oDesk Combination, another redeemable convertible preferred stock warrant that was originally issued by Elance prior to the Elance-oDesk Combination became exercisable to purchase up to 124,506 and 273,825 shares of the Company’s Series A-1 and Series A-2 redeemable convertible preferred stock, respectively, at an exercise price of $3.13 per share. The warrant was outstanding and exercisable as of December 31, 2016 and 2017. Upon completion of the Company’s IPO in October 2018, this warrant converted to a common stock warrant for the same number of shares and was reclassified to additional paid-in capital as of December 31, 2018.

Prior to the IPO, the Company estimated the fair value of each redeemable convertible preferred stock warrant using the Black-Scholes valuation model. The redeemable convertible preferred stock liability, included in other noncurrent liabilities, was $7.2 million as of the date of the IPO and $1.1 million as of December 31, 2017 and 2016. The following assumptions were used to calculate the estimated fair value of the then-outstanding warrants until the closing date of the Company’s IPO and as of December 31, 2017 and 2016:



	2017		2016
Dividend yield	0	%	0	%
Expected term (in years)	2.75		0.50 - 3.75
Risk-free interest rates	1.8	%	1.0% - 1.6%
Expected volatility	34.6	%	34.8% - 39.2%

Common Stock Warrant

As a result of the Elance-oDesk Combination, a common stock warrant that was originally issued by oDesk prior to the Elance-oDesk Combination became exercisable to purchase up to 45,286 shares of common stock at an exercise price of $0.06 per share. The warrant was outstanding and exercisable as of December 31, 2016 and 2017 with the fair value of the warrant reflected in additional paid-in capital in the consolidated balance sheets. In May 2018, the Company issued 45,286 shares of common stock upon the exercise of this common stock warrant.

In April 2018, the Company established The Upwork Foundation initiative. The program will include a donor-advised fund created through the Tides Foundation. In May 2018, the Company issued a warrant to purchase 500,000 shares of its common stock at an exercise price of $0.01 per share to the Tides Foundation. The vesting and exercisability provisions of the warrant became effective upon the Company’s IPO in October 2018.

This warrant is exercisable as to 1/10th of the shares on each anniversary of the IPO, with proceeds from the sale of such shares to be donated in accordance with the Company’s directive. For the year ended December 31, 2018, the Company recorded $0.2 million of expense related to the revaluation of this warrant, which is included in general and administrative expense in the Company’s consolidated statement of operations.

Common Stock

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Common Stock

Holders of common stock are entitled to one vote per share and are entitled to receive dividends, if any, on a pro rata basis whenever funds are legally available and when, as, and if declared by the Company’s board of directors.

As of December 31, 2018 and 2017, the Company was authorized to issue 490,000,000 and 150,000,000 shares of common stock, respectively. As of December 31, 2018 and 2017, the Company had reserved shares of common stock for future issuance as follows:



	2018	2017
Options issued and outstanding	23,774,279	23,607,746
RSUs issued and outstanding	288,460	—
Warrant to purchase redeemable convertible preferred stock	—	398,331
Warrant to purchase common stock	898,331	45,286
Conversion of redeemable convertible preferred stock	—	61,279,079
Remaining shares reserved for future issuances under 2014 Equity Incentive Plan	—	3,962,024
Remaining shares reserved for future issuances under 2018 Equity Incentive Plan	10,558,306	—
Remaining shares reserved for future issuances under 2018 Employee Stock Purchase Plan	1,700,000	—
Total	37,219,376	89,292,466

Stock-Based Compensation

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

Equity Incentive Plans

Assumed Awards

In connection with the Elance-oDesk Combination, the Company assumed substantially all stock options outstanding under the Elance 1999 Stock Option Plan (the “Elance 1999 Plan”) and the Elance 2009 Stock Option Plan (the “Elance 2009 Plan”). Such assumed options were converted into options to purchase the Company’s common stock. In addition, all stock options outstanding under the oDesk Corporation 2004 Stock Plan (the “oDesk Plan”) were converted into options to purchase shares of the Company’s common stock, with the number of shares that could be purchased under each option reduced by approximately 16.14%. The exercise price of all options was simultaneously increased such that the then-aggregate exercise price payable by holders did not change. These options generally vest over a four-year period from the original date of grant and expire ten years from the original grant date.

2014 Equity Incentive Plan

In March 2014, the Company’s board of directors and, in June 2014, the Company’s stockholders approved the 2014 Equity Incentive Plan (“2014 EIP”). The total number of shares of common stock reserved and available for grant and issuance pursuant to such plan was originally 12,462,985 plus (i) shares that were then subject to outstanding option grants under the oDesk Plan, the Elance 1999 Plan, and the Elance 2009 Plan (collectively, the “Prior Plans”) but subsequently ceased to be subject to an award for any reason other than exercise of a stock option, (ii) shares that had been reserved but not subject to any outstanding awards under the Prior Plans and (iii) shares issued under the Prior Plans that were repurchased, forfeited, or used to pay employee withholding or exercise price obligations. The number of shares available for grant under the 2014 EIP was increased by 3,001,091 shares, 4,500,000 shares and 100,000 shares in August 2014, October 2017 and August 2018, respectively. Under the terms of the 2014 EIP, incentive stock options may be granted at prices not less than 100% of the fair value of the Company’s common stock on the date of grant unless determined in writing by the Company’s board of directors. The options granted under the 2014 EIP generally vest over a four-year period from the original date of grant and expire ten years from the original grant date.

2018 Equity Incentive Plan

In August 2018, the Company’s board of directors and stockholders each adopted the 2018 Equity Incentive Plan (“2018 EIP”), which became effective on the date immediately prior to the date of the IPO. A total of 10,701,505 shares of common stock were initially reserved for issuance pursuant to future awards under the 2018 EIP. On January 1 of each year, shares available for issuance are increased based on the provisions of the 2018 EIP. Any shares subject to outstanding awards under the 2014 EIP that are canceled or repurchased subsequent to the 2018 EIP’s effective date are returned to the pool of shares reserved for issuance under the 2018 EIP. Awards granted under the 2018 EIP may be (i) incentive stock options, (ii) nonqualified stock options, (iii) RSUs, (iv) restricted stock awards or (v) stock appreciation rights, as determined by our board of directors at the time of grant. As of December 31, 2018, 10,558,306 shares were reserved for future issuance under the 2018 EIP.

In July 2018, the Company’s board of directors granted an option exercisable for up to 1,860,000 shares of common stock to the Company’s Chief Executive Officer under the 2018 EIP (the “CEO Award”). The vesting and exercisability of the CEO Award is contingent upon the recipient’s continuous service as the Chief Executive Officer and the achievement of certain measurement objectives during three separate measurement periods within the period of time beginning on January 1, 2019 and ending on December 31, 2023. Each reporting period, the Company assesses the probability that the performance criteria will be met and records expense for those shares that are probable of vesting.

Determination of Fair Value

For the years ended December 31, 2018, 2017 and 2016, the fair value of stock options granted to employees was estimated on the grant date using the Black-Scholes valuation model with the following assumptions:



	2018		2017		2016
Dividend yield	0	%	0	%	0	%
Expected term (in years)	5.2 - 6.1		5.3 - 6.3		6.08
Risk-free interest rates	2.5% - 2.9%		1.9% - 2.2%		1.2% - 2.1%
Expected volatility	38% - 45%		39% - 43%		42% - 45%

Dividend Yield —The dividend yield is assumed to be zero as the Company has never paid dividends and has no current plans to do so.

Expected Term —The expected term represents the period that the Company’s stock-based awards are expected to be outstanding. For awards containing only service conditions, the Company determines the expected term using the simplified method as the Company does not have sufficient historical information to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior. The simplified method deems the term to be the average of the time-to-vesting and the contractual life of the options. The Company uses relevant data, including past exercise patterns, if available, to determine the expected term for performance-based awards.

Risk-Free Interest Rate —The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant for zero-coupon U.S. Treasury notes with maturities approximately equal to the option’s expected term.

Expected Volatility —Since the Company does not have sufficient a trading history of its common stock, the expected volatility is derived from the average historical stock volatilities of several unrelated public companies within the Company’s industry that the Company considers to be comparable to its business over a period equivalent to the expected term of the stock option grants.

Fair Value of Common Stock —Given the absence of a public trading market prior to the IPO, the Company’s board of directors considered numerous objective and subjective factors to determine the fair value of its common stock at each grant date. These factors included, but were not limited to: (i) independent contemporaneous third-party valuations of common stock; (ii) the prices for the Company’s redeemable convertible preferred stock sold to outside investors; (iii) the rights and preferences of redeemable convertible preferred stock relative to common stock; (iv) the lack of marketability of its common stock; (v) developments in the business; and (vi) the likelihood of achieving a liquidity event, such as an IPO or sale of the Company, given prevailing market conditions. Subsequent to the IPO, the fair value of common stock is based on the closing price of the Company’s common stock, as reported on The Nasdaq Global Select Market on the date of grant.

The following table summarizes activity under the Company’s stock option plans:



	Number of Shares Underlying Outstanding Options		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value (in thousands)
Balances at January 1, 2016	20,710,510		$	2.79	8.28	$	8,634
Granted	2,624,450		3.20
Exercised	(272,591	)	0.99
Forfeited and canceled	(2,132,867	)	2.93
Balances at December 31, 2016	20,929,502		2.85		7.58	11,149
Granted	5,803,596		3.58
Exercised	(1,554,944	)	1.64
Forfeited and canceled	(1,570,408	)	2.98
Balances at December 31, 2017	23,607,746		3.10		7.39	22,260
Granted	4,468,523		5.88
Exercised	(3,522,631	)	2.32
Forfeited and canceled	(779,359	)	3.80
Balances at December 31, 2018	23,774,279		3.71		7.10	342,262
Vested and exercisable as of December 31, 2018	13,774,468		3.19		6.13	205,455
Vested and expected to vest as of December 31, 2018	23,774,279		3.71		7.10	342,262

Before the IPO, the aggregate intrinsic value represented the difference between the exercise price of the options and the estimated fair value of the Company’s common stock as determined by its board of directors. Following the IPO, the aggregate intrinsic value represented the difference between the exercise price of the options and the closing price of the Company’s common stock on The Nasdaq Global Select Market on the day prior to the date of exercise. The intrinsic value of options exercised was $18.0 million, $2.9 million and $0.6 million for the years ended December 31, 2018, 2017 and 2016, respectively.

The weighted-average grant-date fair value of options granted was $3.65, $1.54 and $1.41 for the years ended December 31, 2018, 2017 and 2016, respectively. As of December 31, 2018, total unrecognized stock-based compensation cost, net of estimated forfeitures, was $23.0 million, which is expected to be generally recognized on a straight-line basis over a weighted-average period of 3.5 years.

The fair value of RSUs awarded to employees is based on the closing price of the Company’s common stock, as reported on The Nasdaq Global Select Market on the date of grant.

The following table summarizes the RSU activity and related information under the 2018 EIP:



	Number of RSUs Outstanding		Weighted-Average Grant Date Fair Value
Unvested balance - January 1, 2018	—		$	—
Granted	327,202		15.00
Vested	(38,742	)	15.00
Forfeited/canceled	—		—
Unvested balance - December 31, 2018	288,460		$	15.00

During 2018, 35,494 fully vested RSUs were granted to a consultant of the Company, which totaled $0.5 million. The consultant’s estimated tax liability associated with this vesting was $0.2 million. To satisfy this tax liability, the consultant surrendered 12,648 shares of common stock to the Company. The associated tax liability was paid in full prior to December 31, 2018.

As of December 31, 2018, there was $3.8 million of unrecognized stock-based compensation expense related to outstanding RSUs to employees that is expected to be recognized over a weighted-average period of 3 years.

2018 Employee Stock Purchase Plan

In August 2018, the Company’s board of directors and stockholders each adopted the 2018 Employee Stock Purchase Plan (“2018 ESPP”), which became effective prior to the completion of our IPO. A total of 1,700,000 shares of common stock was initially reserved for issuance under the 2018 ESPP. On January 1 of each year, shares available for issuance are increased based on the provisions of the 2018 ESPP. The 2018 ESPP allows eligible employees to purchase shares of our common stock at a discount of up to 15% through payroll deductions of their eligible compensation, subject to any plan limitations. Except for the initial offering period, the 2018 ESPP provides for 24-month offering periods beginning November 15 and May 15 of each year, and each offering period consists of four 6-month purchase periods. For the year ended December 31, 2018, the assumptions used to determine the fair value of the shares to be awarded are as follows:



	2018
Dividend yield	0	%
Expected term (in years)	0.5 - 2.0
Risk-free interest rates	2.4% - 2.9%
Unvested balance - expected volatility	37	%

On each purchase date, eligible employees may purchase the Company’s common stock at a price per share equal to 85% of the lesser of (1) the fair market value of our stock on the offering date or (2) the fair market value of our stock on the purchase date. In the event the price is lower on the last day of any purchase price period, in addition to using that price as the basis for that purchase period, the offering period resets and the new lower price becomes the new offering price for a new 24 month offering period. As of December 31, 2018, 1,700,000 shares were reserved for future issuance under the 2018 ESPP. As of December 31, 2018, there was $1.3 million of unrecognized stock-based compensation expense that is expected to be recognized over the remaining term of the respective offering periods.

Stock-Based Compensation

The following table summarizes the components of stock-based compensation expense recognized in the consolidated statements of operations for the years ended December 31, 2018, 2017 and 2016 (in thousands):



	2018		2017		2016
Cost of revenue	$	282	$	290	$	193
Research and development	3,258		1,797		1,820
Sales and marketing	1,637		1,299		1,052
General and administrative	5,184		3,460		4,201
Total	$	10,361	$	6,846	$	7,266

Stock-Based Compensation to Employees

Stock-based compensation expense related to employees for the year ended December 31, 2018 was $8.6 million, $1.1 million and $0.6 million related to stock option grants, RSU grants, and the 2018 ESPP, respectively. Stock-based compensation expense related to employees for the years ended December 31, 2017 and 2016 was $6.3 million and $6.5 million, respectively, related to stock option grants.

Certain common stockholders (who were employees or former employees of the Company) sold the Company’s common stock in secondary market transactions to third parties in 2017 and 2016. They sold an aggregate of 488,484 shares of common stock for $2.3 million at an average price of $4.72 per share for the year ended December 31, 2017. They sold an aggregate of 324,826 shares of common stock for $1.6 million at an average price of $4.93 per share for the year ended December 31, 2016. The incremental value between the sale price and the fair value of the common stock at each date of sale resulted in aggregate stock-based compensation expense of $0.4 million and $0.5 million for the years ended December 31, 2017 and 2016, respectively. There was an immaterial secondary market transaction during the year ended December 31, 2018.

Stock-Based Compensation to Non-Employees

The Company granted options to purchase 8,500 and 8,000 shares of the Company’s common stock to consultants in conjunction with services performed for the years ended December 31, 2017 and 2016, respectively. Stock-based compensation expense related to non-employees was $0.1 million and $0.2 million for the years ended December 31, 2017 and 2016, respectively. Stock-based compensation expense related to non-employees was immaterial for the year ended December 31, 2018.

Net Loss Per Share Attributable to Common Stockholders

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Net Loss Per Share Attributable to Common Stockholders

Net Loss per Share Attributable to Common Stockholders

The following table sets forth the computation of the Company’s basic and diluted net loss per share attributable to common stockholders for the years ended December 31, 2018, 2017 and 2016 (in thousands, except share and per share data):



	2018			2017			2016
Numerator:
Net loss	$	(19,907	)	$	(4,123	)	$	(16,233	)
Less: Premium on repurchase of redeemable convertible preferred stock	—			(6,506		)	—
Net loss attributable to common stockholders	$	(19,907	)	$	(10,629	)	$	(16,233	)
Denominator:
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted	52,327,518			32,944,714			32,071,604
Net loss per share attributable to common stockholders, basic and diluted	$	(0.38	)	$	(0.32	)	$	(0.51	)

For the years ended December 31, 2018, 2017 and 2016, the following potentially dilutive shares were excluded from the computation of diluted net loss per share attributable to common stockholders because including them would have been anti-dilutive:



	2018	2017	2016
Options to purchase common stock	23,774,279	23,607,746	20,929,502
Common stock issuable upon conversion of redeemable convertible preferred stock	—	61,279,079	65,464,387
Common stock issuable upon exercise of common stock warrants	898,331	45,286	45,286
Common stock issuable upon exercise and redeemable conversion of preferred stock warrants	—	398,331	481,512
Common stock issuable upon vesting of restricted stock units	288,460	—	—
Total	24,961,070	85,330,442	86,920,687

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

For the years ended December 31, 2018, 2017 and 2016, the loss before income taxes consisted of the following (in thousands):



	2018			2017			2016
Domestic	$	(19,925	)	$	(4,153	)	$	(16,271	)
Foreign	33			8			37
Total loss before income taxes	$	(19,892	)	$	(4,145	)	$	(16,234	)

For the years ended December 31, 2018, 2017 and 2016, the components of the income tax benefit (provision) were as follows (in thousands):



	2018			2017		2016
Current:
Federal	$	—		$	—	$	—
State	(11		)	1		2
Foreign	(4		)	21		(1		)
Total current	$	(15	)	$	22	$	1
Deferred:
Federal	$	—		$	—	$	—
State	—			—		—
Foreign	—			—		—
Total deferred	$	—		$	—	$	—
Total income tax benefit (provision)	$	(15	)	$	22	$	1

The Company had an effective tax rate of (0.07)%, 0.53% and 0.01% for the years ended December 31, 2018, 2017 and 2016, respectively. The reconciliation of the statutory federal income tax rate to the Company’s effective tax rate for the years ended December 31, 2018, 2017 and 2016 were as follows:



	2018		2017		2016
Tax at federal statutory rate	21.00	%	34.00	%	34.00	%
State tax, net of federal benefit	1.88		1.03		0.15
Stock-based compensation	(5.84	)	(38.63	)	(8.19	)
Warrant expense	(6.98	)	(1.00	)	(0.03	)
Other items	(1.46	)	(1.10	)	(0.66	)
Research and development credits	10.54		102.35		—
Net operating loss expiration	—		(9.29	)	—
Change in valuation allowance	(19.21	)	458.55		(25.26	)
Rate differential impact of Tax Cuts and Jobs Act of 2017	—		(545.38	)	—
Effective tax rate	(0.07)	%	0.53	%	0.01	%

Deferred income taxes reflect the tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. As of December 31, 2018 and 2017, the significant components of the Company’s deferred tax assets and liabilities were as follows (in thousands):



	2018			2017
Deferred tax assets:
Net operating loss carryforwards	$	38,895		$	39,236
Stock-based compensation	3,096			2,427
Depreciation and amortization	—			245
Non-deductible accrued expenses and reserves	2,916			683
Research and development credits	6,724			4,629
Gross deferred tax assets	51,631			47,220
Deferred tax liabilities:
Acquired intangible assets	(1,298		)	(1,856		)
Depreciation and amortization	(894		)	—
Net deferred tax assets prior to valuation allowance	49,439			45,364
Valuation allowance	(49,439		)	(45,364		)
Net deferred tax assets	$	—		$	—

The Company established a full valuation allowance of $49.4 million, $45.4 million and $64.3 million at December 31, 2018, 2017 and 2016, respectively, against its net deferred tax assets. The Company determines its valuation allowance on deferred tax assets by considering both positive and negative evidence in order to ascertain whether it is more likely than not that deferred tax assets will be realized. Realization of deferred tax assets is dependent upon the generation of future taxable income, if any, the timing and amount of which are uncertain. Due to the history of losses the Company has generated in the past, the Company believes that it is not more likely than not that all of the deferred tax assets can be realized as of December 31, 2018. Accordingly, the Company has recorded a full valuation allowance on its deferred tax assets.

On December 22, 2017, the Tax Cuts and Jobs Act (the “Tax Act”) was signed into law. Among other changes is a permanent reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018. As a result of the reduction in the corporate income tax rate, the Company revalued its net deferred tax asset at December 31, 2017. This resulted in a reduction of $22.6 million in the value of the net deferred tax asset, which was entirely offset by the change in valuation allowance of $22.6 million due to the Company’s full valuation allowance position. Other than the remeasurement of the valuation allowance resulting from the Tax Act, there has been no release of the valuation allowance for all periods presented.

The Tax Act expanded the scope of the $1 million deduction limitation and expended the definition of a “covered person” under Internal Revenue Code (“IRC”) §162(m) for tax years beginning after December 31, 2017. The Tax Act repealed the performance based exception; therefore, all compensation paid to a covered employee in excess of $1 million will be nondeductible, unless it is subject to the transition rule. The Tax Act expended the definition of a “covered employee” to include the Chief Financial Officer and to cover any individual who served as the Chief Executive Officer or Chief Financial Officer at any time during the tax year. The “covered employee” definition has been further expanded to provide that once an employee becomes a covered employee for any tax year beginning after December 31, 2016, the employee will remain a covered employee for all future tax years. The Tax Act does not appear to eliminate the regulatory exception to IRC §162(m) for newly public companies, that allows such companies to be exempt from the deduction limitation for a limited period, generally three years, following an initial public offering. The Company is applying the transition rule and has not limited its executive compensation tax deduction.

On December 22, 2017, the SEC issued Staff Accounting Bulletin 118 (“SAB 118”), which provides guidance on accounting for tax effects of the Tax Act. SAB 118’s measurement period closed on December 22, 2018, one year from the Tax Act’s enactment. In accordance with SAB 118, the Company took a provisional amount of bonus tax depreciation following the provisions under IRC §168(k). Upon finalization, the provisional adjustment did not change, resulting in no adjustment to tax expense. The Tax Act’s impact to the Company’s state income tax rate was less than 1 percent.

The Company has federal net operating loss (“NOL”) carryforwards of approximately $172.3 million and $172.9 million as of December 31, 2018 and 2017, respectively. The federal NOLs generated in the years ended December 31, 1999 through 2017 will begin to expire in 2019 for federal income tax purposes, including $0.9 million in 2019. NOLs originating before January 1, 2018, are eligible to offset taxable income, if not otherwise limited under IRC §382 limitations. NOLs generated after December 31, 2017, have an infinite carryforward period and subject to 80% deduction limitation based upon pre-NOL deduction taxable income. The Company has California NOL carryforwards of approximately $38.5 million and $38.5 million as of December 31, 2018 and 2017, respectively. California NOLs generated in the years ended December 31, 2008 through 2018 will begin to expire in 2028. California NOLs generated before 2008 have expired in accordance the California Revenue Taxation Code and related regulations.

The Company has federal research and development credits (“Credits”) of approximately $8.8 million and $7.1 million as of December 31, 2018 and 2017, respectively. The federal Credit will begin to expire in 2019 through 2038. The Company has California Credits of approximately $9.7 million and $8.3 million as of December 31, 2018 and 2017, respectively. California Credits have an infinite carryforward period.

Utilization of the NOL and Credit carryforwards that were generated prior to January 1, 2018, may be subject to a substantial annual limitation due to ownership change limitations that may have occurred or that could occur in the future, as required by IRC §382 and §383, as well as similar state and foreign provisions.

The Company adopted ASU 2016-09 effective January 1, 2018, on a prospective basis. The Company’s previously unrecognized excess tax benefit of $1.6 million has been recognized as an increase to both the NOL deferred tax asset and the valuation allowance. The tax impact of the adoption was nil.

Uncertain Tax Positions

As of December 31, 2018, the Company’s total amount of unrecognized tax benefits was $11.0 million, none of which would impact the Company’s effective tax rate, if recognized.

For the years ended December 31, 2018, 2017 and 2016, the activity related to the unrecognized tax benefits were as follows (in thousands):



	2018			2017			2016
Gross unrecognized tax benefits—beginning balance	$	10,200		$	17,370		$	14,130
Increase related to tax positions taken during prior year	108			—			—
Decrease related to tax positions taken during prior year	(2		)	(7,739		)	—
Increase related to tax positions taken during current year	667			569			3,240
Gross unrecognized tax benefits—ending balance	$	10,973		$	10,200		$	17,370

For the year ended December 31, 2017, the changes related to prior year uncertain tax positions reflected above is largely attributable to the completion of a study on the qualifying activities related to research and development costs giving rise to research and development tax credits.

The Company recognizes interest and penalties related to uncertain tax positions in income tax expense. To the extent accrued interest and penalties do not ultimately become payable, amounts accrued will be reduced and reflected as a reduction of the provision for income taxes in the period that such determination is made. As of December 31, 2018, the Company did not currently recognize any penalties or interest charges relating to uncertain tax positions. The Company does not anticipate the recorded reserves to change significantly in the next twelve months as the Company has a history of operating losses.

Due to certain tax attribute carryforwards, the tax years 1999 to 2018 remain open to examination by the major taxing jurisdictions in which the Company is subject to tax. As of December 31, 2018, the Company was not under examination by the Internal Revenue Service or any state or foreign tax jurisdiction.

Segment and Geographical Information

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Segment and Geographical Information

The Company operates as one operating and reportable segment for purposes of allocating resources and evaluating financial performance.

The following table sets forth total revenue by type of service for the years ended December 31, 2018, 2017 and 2016 (in thousands):



	2018		2017		2016
Marketplace	$	223,831	$	178,046	$	138,484
Managed services	29,523		24,506		25,961
Total	$	253,354	$	202,552	$	164,445

The Company generates its revenue from freelancers and clients. The following table sets forth total revenue by geographic area based on the billing address of its freelancers and clients for the years ended December 31, 2018, 2017 and 2016 (in thousands):



	2018		2017		2016
Freelancers:
United States	$	40,313	$	26,596	$	21,455
India	25,485		21,880		20,003
Philippines	17,057		14,761		13,394
Rest of world	80,387		68,829		58,519
Total freelancers	163,242		132,066		113,371
Clients:
United States	65,578		55,179		42,455
Rest of world	24,534		15,307		8,619
Total clients	90,112		70,486		51,074
Total	$	253,354	$	202,552	$	164,445

Substantially all of the Company’s long-lived assets were located in the United States as of December 31, 2018 and 2017.

401(k) Plan	12 Months Ended
401(k) Plan	Dec. 31, 2018
Retirement Benefits [Abstract]
401(k) Plan	401(k) Plan The Company offers the Upwork Retirement Savings Plan (“Retirement Plan”), a defined contribution plan that allows employees to contribute a portion of their salary, subject to the annual limits. Under the Retirement Plan, eligible employees may defer a portion of their pretax salaries, but not more than the statutory limits. The Retirement Plan provides for a discretionary employer matching contribution. Starting April 2016, the Company began to make matching contributions equal to 50% of each dollar a participant contributed, subject to a maximum contribution of $5,000 per year. The Company’s total expense for the matching contributions was $1.7 million, $1.2 million and $0.9 million for the years ended December 31, 2018, 2017 and 2016, respectively.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events In February 2019, the Company entered into an agreement for a non-cancellable operating lease for new office space in Santa Clara, California. The Company plans to take possession of the Santa Clara office space for its corporate headquarters and move its corporate headquarters and related operations in the second quarter of 2019 concurrent with the termination of its Mountain View, California office lease. From June 1, 2019 through October 15, 2028, total minimum lease payments under the lease agreement are $14.3 million, with lease payments ranging from $1.4 million to $1.8 million per year.

Basis of Presentation and Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Basis of Presentation and Principles of Consolidation

Use of Estimates

Cash and Cash Equivalents

The Company holds its cash in checking and interest-bearing accounts and investments in money market funds with maturities of 90 days or less from the date of purchase.

Funds Held in Escrow, Including Funds in Transit and Escrow Funds Payable

Funds Held in Escrow, Including Funds in Transit

Escrow Funds Payable

Concentration of Risk

The Company is dependent upon third parties, such as Amazon Web Services, in order to meet the uptime and performance requirements of its clients.

Fair Value of Financial Instruments

The Company believes that the carrying values of the remaining financial instruments approximate their fair values.

Trade and Client Receivables and Related Allowance for Doubtful Accounts

Derivatives, Policy [Policy Text Block]

Derivative Instruments

Property and Equipment

Internal-Use Software and Platform Development Costs

Segment Information

Goodwill, Acquired Intangible Assets, and Other Long-Lived Assets

There was no impairment of long-lived assets in any of the periods presented.

Deferred Offering Costs

Revenue Recognition

Marketplace

The Company’s marketplace revenue is derived from both its Upwork Standard offering and its Upwork Enterprise and other premium offerings.

Upwork Standard

The Company earns fees from freelancers under the Upwork Standard offering as follows:

The Company earns fees from clients under the Upwork Standard offering as follows:

Upwork Enterprise and Other Premium Offerings

The Company earns fees from freelancers under Upwork Enterprise and other premium offerings as follows:

The Company earns fees from clients under Upwork Enterprise and other premium offerings as follows:

Upwork Payroll service fees. Upwork Payroll service fees are recognized on the same basis as described under the Upwork Standard offering.

Managed Services

Multiple-Element Arrangements

Deferred Revenue

Deferred revenue consists of subscription, membership, and connects fees collected in advance of services being rendered.

Cost of Revenue

Research and Development

Advertising Expense

The Company expenses advertising costs as incurred.

Provisions for Transactions Losses

Provision for Transaction Losses

Redeemable Convertible Preferred Stock Warrant Liability

Stock-Based Compensation

Foreign Currency

Comprehensive Loss

Comprehensive loss is equal to the net loss for all periods presented. Accordingly, the consolidated statements of comprehensive loss have been omitted from the consolidated financial statements.

Income Taxes

Net Loss per Share Attributable to Common Stockholders

Recently Accounting Pronouncement

Recent Accounting Pronouncements Not Yet Adopted


•	identification of performance obligations;


•	principal agent considerations;


•	whether the discounts offered under the Company’s tiered pricing program for freelancer service fee result in a “material right” as that term is defined in ASC 606;


•	whether costs to obtain a contract with a customer will be capitalized or expensed;


•	timing of revenue recognition;


•	method of adoption; and


•	revenue disclosures which are expected to expand and may require judgment in certain areas.

Recently Adopted Accounting Pronouncements

Basis of Presentation and Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Schedule of allowance for doubtful accounts

The following table presents the changes in the allowance for doubtful accounts as of December 31, 2018, 2017 and 2016 (in thousands):



	2018			2017			2016
Allowance for doubtful accounts, beginning balance	$	1,577		$	2,473		$	2,057
Provision for doubtful accounts	4,940			2,646			3,693
Amounts written off	(3,685		)	(3,542		)	(3,277		)
Allowance for doubtful accounts, ending balance	$	2,832		$	1,577		$	2,473

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Financial Instruments Measured at Fair Value on a Recurring Basis



	December 31, 2018
	Level I		Level II		Level III		Total
Financial Assets:
Cash Equivalents
Money market funds	$	117,138	$	—	$	—	$	117,138
Total financial assets	$	117,138	$	—	$	—	$	117,138



	December 31, 2017
	Level I		Level II		Level III		Total
Financial Liabilities:
Redeemable convertible preferred stock warrant liability	$	—	$	—	$	1,104	$	1,104
Total financial liabilities	$	—	$	—	$	1,104	$	1,104

Summary of Changes in Fair Value of Redeemable Convertible Preferred Stock Warrants

The following table sets forth a summary of the changes in the fair value of the redeemable convertible preferred stock warrant liability (in thousands):



Fair value at January 1, 2016	$	1,016
Change in fair value	114
Fair value at December 31, 2016	1,130
Change in fair value	118
Reclassification to redeemable convertible preferred stock due to warrant exercise	(144		)
Fair value at December 31, 2017	1,104
Change in fair value	6,056
Conversion to common stock warrant in connection with the initial public offering	(7,160		)
Fair value at December 31, 2018	$	—

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2018

Balance Sheet Related Disclosures [Abstract]

Property and Equipment, Net

Property and equipment, net consisted of the following as of December 31, 2018 and 2017 (in thousands):



	2018			2017
Computer equipment and software	$	3,189		$	5,385
Internal-use software and platform development costs	6,287			2,318
Leasehold improvements	5,783			2,189
Office furniture and fixtures	2,545			1,550
Total property and equipment	17,804			11,442
Less: Accumulated depreciation	(6,989		)	(7,928		)
Property and equipment, net	$	10,815		$	3,514

Schedule of Finite Lived Intangible Assets

All of the Company’s identifiable intangible assets were acquired in March 2014 from the Elance-oDesk Combination. Intangible assets, net consisted of the following (in thousands):



	As of December 31, 2018
	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Trade names	$	2,293	$	2,293	$	—
User relationships	18,678		12,674		6,004
Developed technology	10,356		10,356		—
Domain names	529		529		—
Total	$	31,856	$	25,852	$	6,004



	As of December 31, 2017
	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Trade names	$	2,293	$	2,293	$	—
User relationships	18,678		10,006		8,672
Developed technology	10,356		10,356		—
Domain names	529		529		—
Total	$	31,856	$	23,184	$	8,672

Schedule of Indefinite-Lived Intangible Assets

All of the Company’s identifiable intangible assets were acquired in March 2014 from the Elance-oDesk Combination. Intangible assets, net consisted of the following (in thousands):



	As of December 31, 2018
	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Trade names	$	2,293	$	2,293	$	—
User relationships	18,678		12,674		6,004
Developed technology	10,356		10,356		—
Domain names	529		529		—
Total	$	31,856	$	25,852	$	6,004



	As of December 31, 2017
	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Trade names	$	2,293	$	2,293	$	—
User relationships	18,678		10,006		8,672
Developed technology	10,356		10,356		—
Domain names	529		529		—
Total	$	31,856	$	23,184	$	8,672

Estimated Future Amortization Expense for Acquired Intangible Assets

As of December 31, 2018, the estimated future amortization expense for the acquired intangible assets is as follows (in thousands):



Year Ended December 31,	Estimated Amortization Expense
2019	$	2,668
2020	2,668
2021	668
Total	$	6,004

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following as of December 31, 2018 and 2017 (in thousands):



	2018		2017
Accrued compensation and related benefits	$	9,314	$	8,399
Accrued freelancer costs	2,465		134
Accrued indirect taxes	1,630		1,861
Accrued vendor expenses	6,002		4,198
Accrued payment processing fees	715		593
Other	822		845
Total accrued expenses and other current liabilities	$	20,948	$	16,030

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Aggregate Minimum Lease Payments Under Non-Cancelable Operating Leases

As of December 31, 2018, future aggregate minimum lease payments under the non-cancellable operating leases were as follows (in thousands):



Year Ended December 31,	Minimum Lease Payments
2019	$	3,569
2020	4,683
2021	4,914
2022	5,052
2023	5,194
Thereafter	4,890
Less: rental payments from subleases	(363		)
Total	$	27,939

Debt (Tables)

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Summary of Carrying Value of Debt

The following table presents the carrying value of the Company’s debt as of December 31, 2018 and 2017 (in thousands):



	2018			2017
First term loan—18 months of interest-only payments ending in March 2019 followed by 36 equal monthly installments of principal plus interest, maturing March 2022; interest at Prime plus 0.25% per annum	$	15,000		$	15,000
Second term loan—11 months of interest-only payments ending in October 2018 followed by 47 equal monthly installments of principal plus interest, maturing September 2022. As of September 30, 2018, the Company achieved trailing six-month EBITDA of at least $1.0 million; as a result, the interest-only repayment period extended to March 2019, followed by 42 equal monthly installments of principal plus interest; bears interest at Prime plus 5.25% per annum. As a result of the Company's IPO, the interest rate was reduced to Prime plus 0.25% per annum	9,000			9,000
Line of credit—interest at Prime with accrued interest due monthly; matures September 2020	—			10,000
Total debt	24,000			34,000
Less: Unamortized debt discount issuance costs	(90		)	(167		)
Balance	23,910			33,833
Debt, current	(5,671		)	(10,342		)
Debt, noncurrent	$	18,239		$	23,491
Weighted-average interest rate	6.89		%	5.93		%

Schedule of Maturities of Long-term Debt

Future maturities of principal payments, excluding potential early payments, as of December 31, 2018, were expected to be as follows (in thousands):



Year Ended December 31,	Principal Payments
2019	$	5,679
2020	7,571
2021	7,571
2022	3,179
Total	$	24,000

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

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+ Details

Redeemable Convertible Preferred Stock (Tables)

12 Months Ended

Dec. 31, 2018

Temporary Equity Disclosure [Abstract]

Schedule of Redeemable Convertible Preferred Stock

Redeemable convertible preferred stock as of December 31, 2017 consisted of the following (in thousands, except share data):



	Shares Authorized	Shares Issued and Outstanding	Net Carrying Value		Aggregate Liquidation Preference
Series A-1	10,141,345	9,142,770	$	72,181	$	91,427
Series A-2	60,000,000	47,124,931	65,853		5
Series B-1	5,854,982	4,866,360	27,628		27,787
Series B-2	145,018	145,018	824		828
Total redeemable convertible preferred stock	76,141,345	61,279,079	$	166,486	$	120,047

Preferred and Common Stock Warrants (Tables)

12 Months Ended

Dec. 31, 2018

Redeemable Convertible Preferred Stock Warrants

Assumptions Used to Calculate Fair Value of Outstanding Warrants

The following assumptions were used to calculate the estimated fair value of the then-outstanding warrants until the closing date of the Company’s IPO and as of December 31, 2017 and 2016:



	2017		2016
Dividend yield	0	%	0	%
Expected term (in years)	2.75		0.50 - 3.75
Risk-free interest rates	1.8	%	1.0% - 1.6%
Expected volatility	34.6	%	34.8% - 39.2%

Common Stock (Tables)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Summary of Common Stock Shares Reserved for Future Issuance

As of December 31, 2018 and 2017, the Company had reserved shares of common stock for future issuance as follows:



	2018	2017
Options issued and outstanding	23,774,279	23,607,746
RSUs issued and outstanding	288,460	—
Warrant to purchase redeemable convertible preferred stock	—	398,331
Warrant to purchase common stock	898,331	45,286
Conversion of redeemable convertible preferred stock	—	61,279,079
Remaining shares reserved for future issuances under 2014 Equity Incentive Plan	—	3,962,024
Remaining shares reserved for future issuances under 2018 Equity Incentive Plan	10,558,306	—
Remaining shares reserved for future issuances under 2018 Employee Stock Purchase Plan	1,700,000	—
Total	37,219,376	89,292,466

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

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+ Details

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Fair Value Assumptions on Stock Options Granted



	2018		2017		2016
Dividend yield	0	%	0	%	0	%
Expected term (in years)	5.2 - 6.1		5.3 - 6.3		6.08
Risk-free interest rates	2.5% - 2.9%		1.9% - 2.2%		1.2% - 2.1%
Expected volatility	38% - 45%		39% - 43%		42% - 45%

Summary of Activity under Stock Option Plans

The following table summarizes activity under the Company’s stock option plans:



	Number of Shares Underlying Outstanding Options		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value (in thousands)
Balances at January 1, 2016	20,710,510		$	2.79	8.28	$	8,634
Granted	2,624,450		3.20
Exercised	(272,591	)	0.99
Forfeited and canceled	(2,132,867	)	2.93
Balances at December 31, 2016	20,929,502		2.85		7.58	11,149
Granted	5,803,596		3.58
Exercised	(1,554,944	)	1.64
Forfeited and canceled	(1,570,408	)	2.98
Balances at December 31, 2017	23,607,746		3.10		7.39	22,260
Granted	4,468,523		5.88
Exercised	(3,522,631	)	2.32
Forfeited and canceled	(779,359	)	3.80
Balances at December 31, 2018	23,774,279		3.71		7.10	342,262
Vested and exercisable as of December 31, 2018	13,774,468		3.19		6.13	205,455
Vested and expected to vest as of December 31, 2018	23,774,279		3.71		7.10	342,262

Summary of Activity under RSU Plans

The following table summarizes the RSU activity and related information under the 2018 EIP:



	Number of RSUs Outstanding		Weighted-Average Grant Date Fair Value
Unvested balance - January 1, 2018	—		$	—
Granted	327,202		15.00
Vested	(38,742	)	15.00
Forfeited/canceled	—		—
Unvested balance - December 31, 2018	288,460		$	15.00

Summary of Fair Value Assumptions on Employee Stock Purchas Plans

For the year ended December 31, 2018, the assumptions used to determine the fair value of the shares to be awarded are as follows:



	2018
Dividend yield	0	%
Expected term (in years)	0.5 - 2.0
Risk-free interest rates	2.4% - 2.9%
Unvested balance - expected volatility	37	%

Summary of Components of Stock-Based Compensation Expense Recognized



	2018		2017		2016
Cost of revenue	$	282	$	290	$	193
Research and development	3,258		1,797		1,820
Sales and marketing	1,637		1,299		1,052
General and administrative	5,184		3,460		4,201
Total	$	10,361	$	6,846	$	7,266

Net Loss Per Share Attributable to Common Stockholders (Tables)

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders



	2018			2017			2016
Numerator:
Net loss	$	(19,907	)	$	(4,123	)	$	(16,233	)
Less: Premium on repurchase of redeemable convertible preferred stock	—			(6,506		)	—
Net loss attributable to common stockholders	$	(19,907	)	$	(10,629	)	$	(16,233	)
Denominator:
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted	52,327,518			32,944,714			32,071,604
Net loss per share attributable to common stockholders, basic and diluted	$	(0.38	)	$	(0.32	)	$	(0.51	)

Schedule of Potentially Dilutive Shares Excluded from Computation of Diluted Net Loss Per Share Attributable to Common Stockholders



	2018	2017	2016
Options to purchase common stock	23,774,279	23,607,746	20,929,502
Common stock issuable upon conversion of redeemable convertible preferred stock	—	61,279,079	65,464,387
Common stock issuable upon exercise of common stock warrants	898,331	45,286	45,286
Common stock issuable upon exercise and redeemable conversion of preferred stock warrants	—	398,331	481,512
Common stock issuable upon vesting of restricted stock units	288,460	—	—
Total	24,961,070	85,330,442	86,920,687

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Schedule of Income before Income Tax

For the years ended December 31, 2018, 2017 and 2016, the loss before income taxes consisted of the following (in thousands):



	2018			2017			2016
Domestic	$	(19,925	)	$	(4,153	)	$	(16,271	)
Foreign	33			8			37
Total loss before income taxes	$	(19,892	)	$	(4,145	)	$	(16,234	)

Schedule of Components of Income Tax Expense

For the years ended December 31, 2018, 2017 and 2016, the components of the income tax benefit (provision) were as follows (in thousands):



	2018			2017		2016
Current:
Federal	$	—		$	—	$	—
State	(11		)	1		2
Foreign	(4		)	21		(1		)
Total current	$	(15	)	$	22	$	1
Deferred:
Federal	$	—		$	—	$	—
State	—			—		—
Foreign	—			—		—
Total deferred	$	—		$	—	$	—
Total income tax benefit (provision)	$	(15	)	$	22	$	1

Schedule of Effective Income Tax Rate Reconciliation

The reconciliation of the statutory federal income tax rate to the Company’s effective tax rate for the years ended December 31, 2018, 2017 and 2016 were as follows:



	2018		2017		2016
Tax at federal statutory rate	21.00	%	34.00	%	34.00	%
State tax, net of federal benefit	1.88		1.03		0.15
Stock-based compensation	(5.84	)	(38.63	)	(8.19	)
Warrant expense	(6.98	)	(1.00	)	(0.03	)
Other items	(1.46	)	(1.10	)	(0.66	)
Research and development credits	10.54		102.35		—
Net operating loss expiration	—		(9.29	)	—
Change in valuation allowance	(19.21	)	458.55		(25.26	)
Rate differential impact of Tax Cuts and Jobs Act of 2017	—		(545.38	)	—
Effective tax rate	(0.07)	%	0.53	%	0.01	%

Schedule of Deferred Tax Assets and Liabilities

As of December 31, 2018 and 2017, the significant components of the Company’s deferred tax assets and liabilities were as follows (in thousands):



	2018			2017
Deferred tax assets:
Net operating loss carryforwards	$	38,895		$	39,236
Stock-based compensation	3,096			2,427
Depreciation and amortization	—			245
Non-deductible accrued expenses and reserves	2,916			683
Research and development credits	6,724			4,629
Gross deferred tax assets	51,631			47,220
Deferred tax liabilities:
Acquired intangible assets	(1,298		)	(1,856		)
Depreciation and amortization	(894		)	—
Net deferred tax assets prior to valuation allowance	49,439			45,364
Valuation allowance	(49,439		)	(45,364		)
Net deferred tax assets	$	—		$	—

Summary of Unrecognized Tax Benefits

For the years ended December 31, 2018, 2017 and 2016, the activity related to the unrecognized tax benefits were as follows (in thousands):



	2018			2017			2016
Gross unrecognized tax benefits—beginning balance	$	10,200		$	17,370		$	14,130
Increase related to tax positions taken during prior year	108			—			—
Decrease related to tax positions taken during prior year	(2		)	(7,739		)	—
Increase related to tax positions taken during current year	667			569			3,240
Gross unrecognized tax benefits—ending balance	$	10,973		$	10,200		$	17,370

Segment and Geographical Information (Tables)

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Revenue by Type of Service

The following table sets forth total revenue by type of service for the years ended December 31, 2018, 2017 and 2016 (in thousands):



	2018		2017		2016
Marketplace	$	223,831	$	178,046	$	138,484
Managed services	29,523		24,506		25,961
Total	$	253,354	$	202,552	$	164,445

Revenue by Geographic Area Based on Billing Address of Freelancers and Clients

The following table sets forth total revenue by geographic area based on the billing address of its freelancers and clients for the years ended December 31, 2018, 2017 and 2016 (in thousands):



	2018		2017		2016
Freelancers:
United States	$	40,313	$	26,596	$	21,455
India	25,485		21,880		20,003
Philippines	17,057		14,761		13,394
Rest of world	80,387		68,829		58,519
Total freelancers	163,242		132,066		113,371
Clients:
United States	65,578		55,179		42,455
Rest of world	24,534		15,307		8,619
Total clients	90,112		70,486		51,074
Total	$	253,354	$	202,552	$	164,445

Organization and Description of Business (Details) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2015 platform
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating platforms consolidated \| platform		2
Subsidiary, Sale of Stock [Line Items]
Consideration received on stock transaction \| $	$ 109.4
IPO
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in stock transaction \| shares	7,840,908
Price per share of stock transaction (in dollars per share) \| $ / shares	$ 15.00
Underwriters' Option
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in stock transaction \| shares	1,022,727
Price per share of stock transaction (in dollars per share) \| $ / shares	$ 1.05

Basis of Presentation and Summary of Significant Accounting Policies - Narrative (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Subsidiary, Sale of Stock [Line Items]
Restricted cash	$ 2,700,000	$ 2,300,000
Restricted cash, current	2,200,000	1,800,000
Restricted cash, noncurrent	500,000	500,000
Escrow funds payable	98,186,000	87,195,000
Revenue	253,354,000	202,552,000	$ 164,445,000
Gross trade receivables	9,100,000	8,600,000
Gross client receivables	$ 16,000,000	23,800,000
Capitalized costs, amortization period	2 years
Capitalized costs	$ 4,000,000	500,000	0
Internal-use software and platform development costs capitalized	600,000
Internal-use software and platform development costs capitalized, amortization expense	$ 100,000	0	1,000,000
Number of reportable segments \| segment	1
Goodwill impairment	$ 0
Capitalized deferred offering costs		100,000
Deferred offering costs		6,300,000
Advertising expense	23,600,000	14,600,000	10,800,000
Foreign currency transactions gain (loss)	$ (400,000)		(500,000)
Minimum
Subsidiary, Sale of Stock [Line Items]
Property and equipment, useful lives	3 years
Intangible asset, useful life	2 years
Maximum
Subsidiary, Sale of Stock [Line Items]
Property and equipment, useful lives	5 years
Intangible asset, useful life	7 years
Foreign Currency Forward Contracts
Subsidiary, Sale of Stock [Line Items]
Notional amount on derivatives	$ 4,800,000	3,600,000
Loss on derivatives	400,000		$ 500,000
Client Accounting For More than 10% revenue
Subsidiary, Sale of Stock [Line Items]
Revenue	$ 29,500,000	$ 24,500,000

Basis of Presentation and Summary of Significant Accounting Policies - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for Doubtful Accounts Receivable [Roll Forward]
Allowance for doubtful accounts, beginning balance	$ 1,577	$ 2,473	$ 2,057
Provision for doubtful accounts	4,940	2,646	3,693
Amounts written off	(3,685)	(3,542)	(3,277)
Allowance for doubtful accounts, ending balance	$ 2,832	$ 1,577	$ 2,473

Fair Value Measurements - Financial Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other expense, net	$ 6,142	$ 62	$ 908
Financial Assets:
Cash Equivalents	117,138
Financial Liabilities:
Total financial liabilities		1,104
Level I
Financial Assets:
Cash Equivalents	117,138
Financial Liabilities:
Total financial liabilities		0
Level II
Financial Assets:
Cash Equivalents	0
Financial Liabilities:
Total financial liabilities		0
Level III
Financial Assets:
Cash Equivalents	0
Financial Liabilities:
Total financial liabilities		1,104
Money market funds
Financial Assets:
Cash Equivalents	117,138
Money market funds \| Level I
Financial Assets:
Cash Equivalents	117,138
Money market funds \| Level II
Financial Assets:
Cash Equivalents	0
Money market funds \| Level III
Financial Assets:
Cash Equivalents	0
Redeemable convertible preferred stock warrant liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other expense, net	$ 6,100	100	$ 100
Financial Liabilities:
Total financial liabilities		1,104
Redeemable convertible preferred stock warrant liability \| Level I
Financial Liabilities:
Total financial liabilities		0
Redeemable convertible preferred stock warrant liability \| Level II
Financial Liabilities:
Total financial liabilities		0
Redeemable convertible preferred stock warrant liability \| Level III
Financial Liabilities:
Total financial liabilities		$ 1,104

Fair Value Measurements - Redeemable Convertible Preferred Stock Warrants (Details) - Redeemable convertible preferred stock warrant liability - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	$ 1,104	$ 1,130	$ 1,016
Change in fair value	6,056	118	114
Conversion to common stock warrant in connection with the initial public offering	(7,160)	(144)
Fair value, ending balance	$ 0	$ 1,104	$ 1,130

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 17,804	$ 11,442
Less: Accumulated depreciation	(6,989)	(7,928)
Property and equipment, net	10,815	3,514
Computer equipment and software
Property, Plant and Equipment [Line Items]
Total property and equipment	3,189	5,385
Internal-use software and platform development costs
Property, Plant and Equipment [Line Items]
Total property and equipment	6,287	2,318
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	5,783	2,189
Office furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 2,545	$ 1,550

Balance Sheet Components - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 2,200,000	$ 1,500,000	$ 1,800,000
Capitalized costs	4,000,000	500,000	0
Internal-use software and platform development costs capitalized, amortization expense	100,000	0	1,000,000
Amortization of intangible assets	2,700,000	2,700,000	5,700,000
Carrying amount	6,004,000	8,672,000
Developed technology and trade names
Property, Plant and Equipment [Line Items]
Amortization of intangible assets			2,900,000
Developed technology
Property, Plant and Equipment [Line Items]
Carrying amount	$ 0	0	2,600,000
User relationships
Property, Plant and Equipment [Line Items]
Amortization of intangible assets			$ 2,700,000
Intangible asset, useful life	2 years 3 months 18 days
Carrying amount	$ 6,004,000	$ 8,672,000

Balance Sheet Components - Intangible Assets, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 31,856	$ 31,856
Accumulated Amortization	25,852	23,184
Net Carrying Amount	6,004	8,672
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,293	2,293
Accumulated Amortization	2,293	2,293
Net Carrying Amount	0	0
User relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	18,678	18,678
Accumulated Amortization	12,674	10,006
Net Carrying Amount	6,004	8,672
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	10,356	10,356
Accumulated Amortization	10,356	10,356
Net Carrying Amount	0	0	$ 2,600
Domain names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	529	529
Accumulated Amortization	529	529
Net Carrying Amount	$ 0	$ 0

Balance Sheet Components - Future Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2019	$ 2,668
2020	2,668
2021	668
Net Carrying Amount	$ 6,004	$ 8,672

Balance Sheet Components - Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accrued Liabilities and Other Liabilities [Abstract]
Accrued compensation and related benefits	$ 9,314	$ 8,399
Accrued freelancer costs	2,465	134
Accrued indirect taxes	1,630	1,861
Accrued vendor expenses	6,002	4,198
Accrued payment processing fees	715	593
Other	822	845
Total accrued expenses and other current liabilities	$ 20,948	$ 16,030

Commitments and Contingencies - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) agreement letter	Dec. 31, 2017 USD ($) letter	Dec. 31, 2016 USD ($)
Commitment And Contingencies [Line Items]
Number of non-cancellable operating lease agreements \| agreement	4
Total	$ 27,939
2019	3,569
2020	4,683
2021	4,914
2022	5,052
2023	5,194
Rent expense	$ 4,200	$ 3,700	$ 3,600
Letters of credit (in letter) \| letter	3	2
Letters of credit outstanding, amount	$ 800	$ 800
Accrued settlement costs			1,100
Office Space in San Francisco
Commitment And Contingencies [Line Items]
Sublease income		$ 900	$ 900
Total	15,700
Office Space in San Francisco \| Minimum
Commitment And Contingencies [Line Items]
2019	1,000
2020	1,000
2021	1,000
2022	1,000
2023	1,000
2024	1,000
Office Space in San Francisco \| Maximum
Commitment And Contingencies [Line Items]
2019	2,200
2020	2,200
2021	2,200
2022	2,200
2023	2,200
2024	2,200
Office Space in Chicago
Commitment And Contingencies [Line Items]
Total	10,300
Office Space in Chicago \| Minimum
Commitment And Contingencies [Line Items]
2019	500
2020	500
2021	500
2022	500
2023	500
2024	500
Office Space in Chicago \| Maximum
Commitment And Contingencies [Line Items]
2019	2,000
2020	2,000
2021	2,000
2022	2,000
2023	2,000
2024	$ 2,000

Commitments and Contingencies - Future Lease Payments (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2019	$ 3,569
2020	4,683
2021	4,914
2022	5,052
2023	5,194
Thereafter	4,890
Less: rental payments from subleases	(363)
Total	$ 27,939

Debt - Summary of Carrying Value of Debt (Details)	1 Months Ended		8 Months Ended	12 Months Ended
Debt - Summary of Carrying Value of Debt (Details)	Oct. 31, 2018	Sep. 30, 2018 USD ($) installment	Aug. 31, 2018	Dec. 31, 2018 USD ($) installment	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Total debt				$ 24,000,000	$ 34,000,000
Less: Unamortized debt discount issuance costs				(90,000)	(167,000)
Balance				23,910,000	33,833,000
Debt, current				(5,671,000)	(10,342,000)
Debt, noncurrent				$ 18,239,000	$ 23,491,000
Weighted-average interest rate				6.89%	5.93%
First term loan—18 months of interest-only payments ending in March 2019 followed by 36 equal monthly installments of principal plus interest, maturing March 2022; interest at Prime plus 0.25% per annum
Debt Instrument [Line Items]
Total debt				$ 15,000,000	$ 15,000,000
Interest only payments term				18 months
Number of equal monthly installments of principal and interest \| installment				36
First term loan—18 months of interest-only payments ending in March 2019 followed by 36 equal monthly installments of principal plus interest, maturing March 2022; interest at Prime plus 0.25% per annum \| Prime Rate
Debt Instrument [Line Items]
Debt, variable rate				0.25%
Second term loan—11 months of interest-only payments ending in October 2018 followed by 47 equal monthly installments of principal plus interest, maturing September 2022. As of September 30, 2018, the Company achieved trailing six-month EBITDA of at least $1.0 million; as a result, the interest-only repayment period extended to March 2019, followed by 42 equal monthly installments of principal plus interest; bears interest at Prime plus 5.25% per annum. As a result of the Company's IPO, the interest rate
Debt Instrument [Line Items]
Total debt				$ 9,000,000	9,000,000
Interest only payments term				11 months
Number of equal monthly installments of principal and interest \| installment		42		47
EBITDA, trailing period		6 months
EBITDA		$ 1,000,000.0
Second term loan—11 months of interest-only payments ending in October 2018 followed by 47 equal monthly installments of principal plus interest, maturing September 2022. As of September 30, 2018, the Company achieved trailing six-month EBITDA of at least $1.0 million; as a result, the interest-only repayment period extended to March 2019, followed by 42 equal monthly installments of principal plus interest; bears interest at Prime plus 5.25% per annum. As a result of the Company's IPO, the interest rate \| Prime Rate
Debt Instrument [Line Items]
Debt, variable rate	0.25%	5.25%	5.25%
Line of credit—interest at Prime with accrued interest due monthly; matures September 2020
Debt Instrument [Line Items]
Total debt				$ 0	$ 10,000,000

Debt - Narrative (Details) - USD ($)	1 Months Ended				8 Months Ended	12 Months Ended
Debt - Narrative (Details) - USD ($)	Oct. 31, 2018	Sep. 30, 2018	Nov. 30, 2017	Sep. 30, 2017	Aug. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 49,000,000.0				$ 30,000,000.0
Debt issuance costs			200,000
Proceeds from borrowings		$ 15,000,000
Adjusted liquidity ratio						1.30%
Repurchase of redeemable convertible preferred stock							19,000,000
Net proceeds		$ 50,000,000
Upon achieving adjusted net revenue of at least $49.0 million in a trailing three-month period
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity							40,000,000.0
Revolving Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity							15,000,000.0
Proceeds from borrowings			10,000,000
Revolving Line of Credit \| Upon achieving adjusted net revenue of at least $49.0 million in a trailing three-month period
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity							25,000,000.0
First Term Loan
Debt Instrument [Line Items]
Debt instrument, face amount							$ 15,000,000.0
First Term Loan \| Prime Rate
Debt Instrument [Line Items]
Debt, variable rate						0.25%
Second Term Loan
Debt Instrument [Line Items]
Debt instrument, face amount			9,000,000.0
EBITDA, trailing period		6 months
Second Term Loan \| Prime Rate
Debt Instrument [Line Items]
Debt, variable rate	0.25%	5.25%			5.25%
Term Loan
Debt Instrument [Line Items]
Proceeds from borrowings			$ 9,000,000
Loan Agreement
Debt Instrument [Line Items]
Repayment of debt owed	$ 10,000,000
Minimum
Debt Instrument [Line Items]
EBITDA, trailing period						3 months
Minimum \| Upon achieving adjusted net revenue of at least $49.0 million in a trailing three-month period
Debt Instrument [Line Items]
Adjusted net revenue				$ 49,000,000.0
Maximum
Debt Instrument [Line Items]
EBITDA, trailing period						12 months

Debt - Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
2019	$ 5,679
2020	7,571
2021	7,571
2022	3,179
Year Ended December 31,	$ 24,000	$ 34,000

Redeemable Convertible Preferred Stock - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Oct. 31, 2018	Nov. 30, 2017	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2016	Dec. 31, 2015
Redeemable Noncontrolling Interest [Line Items]
Redeemable convertible preferred stock, shares outstanding (in shares)			61,279,079	0	65,464,387	65,464,387
Temporary equity redemption terms, change in control threshold			50.00%
Dividends declared on the Preferred Stock			$ 0
Voting right protective provision, shares outstanding threshold			15,100,000
Voting right protective provision, approval percentage			50.00%
Convertible preferred stock conversion terms, minimum threshold from initial public offering			$ 50,000
Conversion ratio			100.00%
Repurchase and retirement of redeemable convertible preferred stock (in shares)			4,268,489
Repurchase of redeemable convertible preferred stock, price per share (in dollars per share)		$ 4.50
Repurchase of redeemable convertible preferred stock, consideration received			$ 19,200
Repurchase of redeemable convertible preferred stock, carrying value			12,703
Repurchase of redeemable convertible preferred stock			6,506
Additional Paid-in Capital
Redeemable Noncontrolling Interest [Line Items]
Repurchase of redeemable convertible preferred stock			$ 6,506
Series A-1
Redeemable Noncontrolling Interest [Line Items]
Redeemable convertible preferred stock, shares outstanding (in shares)			9,142,770
Dividends payable, amount per share (in dollars per share)			$ 0.80
Issue price per share (in dollars per share)			10.00
Liquidation preference per share (in dollars per share)			$ 10
Repurchase and retirement of redeemable convertible preferred stock (in shares)		874,069
Series A-2
Redeemable Noncontrolling Interest [Line Items]
Redeemable convertible preferred stock, shares outstanding (in shares)			47,124,931
Dividends payable, amount per share (in dollars per share)			$ 0.000008
Issue price per share (in dollars per share)			0.0001
Liquidation preference per share (in dollars per share)			$ 0.0001
Repurchase and retirement of redeemable convertible preferred stock (in shares)		3,151,858
Series B-1
Redeemable Noncontrolling Interest [Line Items]
Redeemable convertible preferred stock, shares outstanding (in shares)			4,866,360
Dividends payable, amount per share (in dollars per share)			$ 0.4568
Issue price per share (in dollars per share)			5.71
Liquidation preference per share (in dollars per share)			$ 5.71
Repurchase and retirement of redeemable convertible preferred stock (in shares)		242,562
Series B-2
Redeemable Noncontrolling Interest [Line Items]
Redeemable convertible preferred stock, shares outstanding (in shares)			145,018
Dividends payable, amount per share (in dollars per share)			$ 0.4568
Issue price per share (in dollars per share)			5.71
Liquidation preference per share (in dollars per share)			$ 5.71
IPO
Redeemable Noncontrolling Interest [Line Items]
Number of shares issued in stock transaction	7,840,908
Price per share of stock transaction (in dollars per share)	$ 15.00

Redeemable Convertible Preferred Stock - Schedule of Redeemable Convertible Preferred Stock (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Temporary Equity [Line Items]
Shares Authorized (in shares)		76,141,345
Shares Issued (in shares)		61,279,079
Shares Outstanding (in shares)	0	61,279,079	65,464,387	65,464,387
Net Carrying Value	$ 0	$ 166,486	$ 178,785	$ 178,785
Aggregate Liquidation Preference		$ 120,047
Series A-1
Temporary Equity [Line Items]
Shares Authorized (in shares)		10,141,345
Shares Issued (in shares)		9,142,770
Shares Outstanding (in shares)		9,142,770
Net Carrying Value		$ 72,181
Aggregate Liquidation Preference		$ 91,427
Series A-2
Temporary Equity [Line Items]
Shares Authorized (in shares)		60,000,000
Shares Issued (in shares)		47,124,931
Shares Outstanding (in shares)		47,124,931
Net Carrying Value		$ 65,853
Aggregate Liquidation Preference		$ 5
Series B-1
Temporary Equity [Line Items]
Shares Authorized (in shares)		5,854,982
Shares Issued (in shares)		4,866,360
Shares Outstanding (in shares)		4,866,360
Net Carrying Value		$ 27,628
Aggregate Liquidation Preference		$ 27,787
Series B-2
Temporary Equity [Line Items]
Shares Authorized (in shares)		145,018
Shares Issued (in shares)		145,018
Shares Outstanding (in shares)		145,018
Net Carrying Value		$ 824
Aggregate Liquidation Preference		$ 828

Preferred and Common Stock Warrants - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 03, 2018	May 31, 2018	Jun. 30, 2017
Class of Warrant or Right [Line Items]
Common stock warrant exercisable conversion	10.00%
Revaluation of warrant expense	$ 226	$ 0	$ 0
Other Liabilities, Noncurrent
Class of Warrant or Right [Line Items]
Fair value of redeemable convertible preferred stock liability		$ 1,100	$ 1,100	$ 7,200
Redeemable Convertible Preferred Stock Warrants, One \| Series A-1
Class of Warrant or Right [Line Items]
Exercise price of warrants (in dollars per share)						$ 3.13
Redeemable Convertible Preferred Stock Warrants, One \| Series A-1 \| Maximum
Class of Warrant or Right [Line Items]
Number of shares issued upon exercisable of warrants						26,000
Redeemable Convertible Preferred Stock Warrants, One \| Series A-2 \| Maximum
Class of Warrant or Right [Line Items]
Number of shares issued upon exercisable of warrants						57,181
Redeemable Convertible Preferred Stock Warrants \| Series A-1
Class of Warrant or Right [Line Items]
Exercise price of warrants (in dollars per share)	$ 3.13
Redeemable Convertible Preferred Stock Warrants \| Series A-1 \| Maximum
Class of Warrant or Right [Line Items]
Number of shares issued upon exercisable of warrants	124,506
Redeemable Convertible Preferred Stock Warrants \| Series A-2 \| Maximum
Class of Warrant or Right [Line Items]
Number of shares issued upon exercisable of warrants	273,825
Common Stock Warrant
Class of Warrant or Right [Line Items]
Exercise price of warrants (in dollars per share)	$ 0.06
Shares issued upon exercise of warrants					45,286
Common Stock Warrant \| Tides Foundation
Class of Warrant or Right [Line Items]
Number of shares issued upon exercisable of warrants					500,000
Exercise price of warrants (in dollars per share)					$ 0.01
Common Stock Warrant \| Maximum
Class of Warrant or Right [Line Items]
Number of shares issued upon exercisable of warrants	45,286

Preferred and Common Stock Warrants - Assumptions Used to Calculate Fair Value of Outstanding Warrants (Details) - Redeemable Convertible Preferred Stock Warrants	Dec. 31, 2017	Dec. 31, 2016
Dividend Yield
Class of Warrant or Right [Line Items]
Outstanding warrants measurement input	0	0
Expected Term
Class of Warrant or Right [Line Items]
Outstanding warrants measurement input	2 years 9 months
Expected Term \| Minimum
Class of Warrant or Right [Line Items]
Outstanding warrants measurement input		6 months
Expected Term \| Maximum
Class of Warrant or Right [Line Items]
Outstanding warrants measurement input		3 years 9 months
Risk-Free Interest Rates
Class of Warrant or Right [Line Items]
Outstanding warrants measurement input	0.018
Risk-Free Interest Rates \| Minimum
Class of Warrant or Right [Line Items]
Outstanding warrants measurement input		0.010
Risk-Free Interest Rates \| Maximum
Class of Warrant or Right [Line Items]
Outstanding warrants measurement input		0.016
Expected Volatility
Class of Warrant or Right [Line Items]
Outstanding warrants measurement input	0.346
Expected Volatility \| Minimum
Class of Warrant or Right [Line Items]
Outstanding warrants measurement input		0.348
Expected Volatility \| Maximum
Class of Warrant or Right [Line Items]
Outstanding warrants measurement input		0.392

Common Stock - Narrative (Details)	Dec. 31, 2018 vote shares	Sep. 30, 2018 shares	Dec. 31, 2017 shares
Equity [Abstract]
Common Stock, votes per share (in votes) \| vote	1
Common stock, shares authorized (in shares) \| shares	490,000,000	490,000,000	150,000,000

Common Stock - Reserved for Future Issuance (Details) - shares	Dec. 31, 2018	Aug. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Common stock shares reserved for future issuance (in shares)	37,219,376		89,292,466
2014 Equity Incentive Plan
Class of Stock [Line Items]
Common stock shares reserved for future issuance (in shares)	0		3,962,024
2018 Equity Incentive Plan
Class of Stock [Line Items]
Common stock shares reserved for future issuance (in shares)	10,558,306	10,701,505	0
2018 Employee Stock Purchase Plan
Class of Stock [Line Items]
Common stock shares reserved for future issuance (in shares)	1,700,000	1,700,000	0
Warrant to purchase redeemable convertible preferred stock
Class of Stock [Line Items]
Common stock shares reserved for future issuance (in shares)	0		398,331
Warrant to purchase common stock
Class of Stock [Line Items]
Common stock shares reserved for future issuance (in shares)	898,331		45,286
Conversion of redeemable convertible preferred stock
Class of Stock [Line Items]
Common stock shares reserved for future issuance (in shares)	0		61,279,079
Options issued and outstanding
Class of Stock [Line Items]
Common stock shares reserved for future issuance (in shares)	23,774,279		23,607,746
RSUs issued and outstanding
Class of Stock [Line Items]
Common stock shares reserved for future issuance (in shares)	288,460		0

Stock-Based Compensation - Narrative (Details) $ / shares in Units, $ in Thousands	1 Months Ended			4 Months Ended	12 Months Ended
	Aug. 31, 2018 offering_period shares	Oct. 31, 2017 shares	Aug. 31, 2014 shares	Jun. 30, 2014 shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Jul. 31, 2018 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares reserved for future issuance (in shares) \| shares					37,219,376	89,292,466
Dividend yield					0.00%
Intrinsic value of options exercised					$ 18,000	$ 2,900	$ 600
Weighted-average grant-date fair value of options granted (in dollars per share) \| $ / shares					$ 3.65	$ 1.54	$ 1.41
Total					$ 10,361	$ 6,846	$ 7,266
Issuance of common stock in connection with the initial public offering, net of discounts and commissions					$ 109,381
Nonemployee shares granted (in shares) \| shares						8,500	8,000
Stock-based compensation expense related to non-employee services						$ 100	$ 200
Secondary Market Transactions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total						$ 400	$ 500
Number of shares issued and sold (in shares) \| shares						488,484	324,826
Issuance of common stock in connection with the initial public offering, net of discounts and commissions						$ 2,300	$ 1,600
Secondary Market Transactions \| Average
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Average share price (in dollars per share) \| $ / shares						$ 4.72	$ 4.93
Options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares reserved for future issuance (in shares) \| shares					23,774,279	23,607,746
Total					$ 8,600	$ 6,300	$ 6,500
RSUs issued and outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares reserved for future issuance (in shares) \| shares					288,460	0
Fully vested non-option equity instruments granted (in shares) \| shares					35,494
Value of equity granted					$ 500
Share-based tax liability of granted shares					$ 200
Shares surrendered to pay for tax liability \| shares					12,648
Total						$ 1,100
ESPP Plan shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total							$ 600
Elance-oDesk Assumed Award Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Discount on share at purchase date from original option price					16.14%
Vesting period					4 years
Expiration period					10 years
2014 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				4 years
Expiration period				10 years
Shares available for grant \| shares				12,462,985
Shares issued in period \| shares	100,000	4,500,000	3,001,091
Grant price, threshold of fair value price must meet				100.00%
Common stock shares reserved for future issuance (in shares) \| shares					0	3,962,024
2018 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares reserved for future issuance (in shares) \| shares	10,701,505				10,558,306	0
Option to purchase shares of common stock, granted \| shares								1,860,000
Dividend yield					0.00%	0.00%	0.00%
2018 Equity Incentive Plan \| Options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation cost, options					$ 23,000
Unrecognized stock-based compensation cost, weighted average period of recognition					3 years 6 months
2018 Equity Incentive Plan \| RSUs issued and outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation cost, options					$ 3,800
Unrecognized stock-based compensation cost, weighted average period of recognition					3 years
2018 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Discount on share at purchase date from original option price	15.00%
Common stock shares reserved for future issuance (in shares) \| shares	1,700,000				1,700,000	0
Dividend yield					0.00%
Unrecognized stock-based compensation cost, options					$ 1,300
Initial offering period of ESPP	24 months
Number of offering periods in ESPP \| offering_period	4
Length of offering period	6 months
Common stock percentage of purchase price	85.00%

Stock-Based Compensation - Fair Value Assumptions (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%
2018 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%
Expected term (in years)			6 years 29 days
2018 Equity Incentive Plan \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	5 years 2 months 12 days	5 years 3 months 18 days
Risk-free interest rates	2.50%	1.90%	1.20%
Expected volatility	38.00%	39.00%	42.00%
2018 Equity Incentive Plan \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years 1 month 6 days	6 years 3 months 18 days
Risk-free interest rates	2.90%	2.20%	2.10%
Expected volatility	45.00%	43.00%	45.00%
2018 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%
Expected volatility	37.00%
2018 Employee Stock Purchase Plan \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 months
Risk-free interest rates	2.40%
2018 Employee Stock Purchase Plan \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	2 years
Risk-free interest rates	2.90%

Stock-Based Compensation - Summary of Activity under Stock Option Plans (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Shares Underlying Outstanding Options
Beginning Balance (in shares)	23,607,746	20,929,502	20,710,510
Granted (in shares)	4,468,523	5,803,596	2,624,450
Exercised (in shares)	(3,522,631)	(1,554,944)	(272,591)
Forfeited and canceled (in shares)	(779,359)	(1,570,408)	(2,132,867)
Ending Balance (in shares)	23,774,279	23,607,746	20,929,502	20,710,510
Vested and exercisable (in shares)	13,774,468
Vested and expected to vest (in shares)	23,774,279
Weighted-Average Exercise Price
Beginning Balance (in dollars per share)	$ 3.10	$ 2.85	$ 2.79
Granted (in dollars per share)	5.88	3.58	3.20
Exercised (in dollars per share)	2.32	1.64	0.99
Forfeited and canceled (in dollars per share)	3.80	2.98	2.93
Ending Balance (in dollars per share)	3.71	$ 3.10	$ 2.85	$ 2.79
Vested and exercisable (in dollars per share)	3.19
Vested and expected to vest (in dollars per share)	$ 3.71
Weighted-Average Remaining Contractual Term (Years)	7 years 1 month 6 days	7 years 4 months 20 days	7 years 6 months 29 days	8 years 3 months 11 days
Weighted-Average Remaining Contractual Term (Years), Vested and exercisable	6 years 1 month 16 days
Weighted-Average Remaining Contractual Term (Years), Vested and expected to vest	7 years 1 month 6 days
Aggregate Intrinsic Value (in thousands), Vested and exercisable	$ 205,455
Aggregate Intrinsic Value (in thousands), Vested and expected to vest	342,262
Aggregate Intrinsic Value (in thousands)	$ 342,262	$ 22,260	$ 11,149	$ 8,634

Stock-Based Compensation - Summary of Activity under Restricted Stock Unit Plans (Details) - RSUs issued and outstanding	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Number of RSUs Outstanding
Unvested balance - beginning balance (in shares) \| shares	0
Granted (in shares) \| shares	327,202
Vested (in shares) \| shares	(38,742)
Forfeited/canceled (in shares) \| shares	0
Unvested balance - ending balance (in shares) \| shares	288,460
Weighted-Average Grant Date Fair Value
Unvested balance - beginning balance (in dollars per share) \| $ / shares	$ 0.00
Granted (in dollars per share) \| $ / shares	15.00
Vested (in dollars per share) \| $ / shares	15.00
Forfeited/canceled (in dollars per share) \| $ / shares	0.00
Unvested balance - ending balance (in dollars per share) \| $ / shares	$ 15.00

Stock-Based Compensation - Components of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total	$ 10,361	$ 6,846	$ 7,266
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total	282	290	193
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total	3,258	1,797	1,820
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total	1,637	1,299	1,052
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total	$ 5,184	$ 3,460	$ 4,201

Net Loss Per Share Attributable to Common Stockholders - Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Numerator:
Net loss	$ (19,907)	$ (4,123)	$ (16,233)
Less: Premium on repurchase of redeemable convertible preferred stock	0	(6,506)	0
Net loss attributable to common stockholders	$ (19,907)	$ (10,629)	$ (16,233)
Denominator:
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted	52,327,518	32,944,714	32,071,604
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.38)	$ (0.32)	$ (0.51)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Net Loss Per Share Attributable to Common Stockholders - Schedule of Potentially Dilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from computation of diluted net loss per share attributable to common stockholders	24,961,070	85,330,442	86,920,687
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from computation of diluted net loss per share attributable to common stockholders	23,774,279	23,607,746	20,929,502
Common stock issuable upon conversion of redeemable convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from computation of diluted net loss per share attributable to common stockholders	0	61,279,079	65,464,387
Common stock issuable upon exercise of common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from computation of diluted net loss per share attributable to common stockholders	898,331	45,286	45,286
Common stock issuable upon exercise and redeemable conversion of preferred stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from computation of diluted net loss per share attributable to common stockholders	0	398,331	481,512
Common stock issuable upon vesting of restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from computation of diluted net loss per share attributable to common stockholders	288,460	0	0

Income Taxes - Loss Before Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Domestic	$ (19,925)	$ (4,153)	$ (16,271)
Foreign	33	8	37
Total loss before income taxes	$ (19,892)	$ (4,145)	$ (16,234)

Income Taxes - Components of Income Tax Benefit (Provision) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal	$ 0	$ 0	$ 0
State	(11)	1	2
Foreign	(4)	21	(1)
Total current	(15)	22	1
Deferred:
Federal	0	0	0
State	0	0	0
Foreign	0	0	0
Total deferred	0	0	0
Total income tax benefit (provision)	$ (15)	$ 22	$ 1

Income Taxes - Effective Tax Rate (Details)	12 Months Ended
Income Taxes - Effective Tax Rate (Details)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Tax at federal statutory rate	21.00%	34.00%	34.00%
State tax, net of federal benefit	1.88%	1.03%	0.15%
Stock-based compensation	(5.84%)	(38.63%)	(8.19%)
Warrant expense	(6.98%)	(1.00%)	(0.03%)
Other items	(1.46%)	(1.10%)	(0.66%)
Research and development credits	10.54%	102.35%	0.00%
Net operating loss expiration	0.00%	(9.29%)	0.00%
Change in valuation allowance	(19.21%)	458.55%	(25.26%)
Rate differential impact of Tax Cuts and Jobs Act of 2017	0.00%	(545.38%)	0.00%
Effective tax rate	(0.07%)	0.53%	0.01%

Income Taxes - Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Net operating loss carryforwards	$ 38,895	$ 39,236
Stock-based compensation	3,096	2,427
Depreciation and amortization	0	245
Non-deductible accrued expenses and reserves	2,916	683
Research and development credits	6,724	4,629
Gross deferred tax assets	51,631	47,220
Deferred tax liabilities:
Acquired intangible assets	(1,298)	(1,856)
Depreciation and amortization	(894)	0
Net deferred tax assets prior to valuation allowance	49,439	45,364
Valuation allowance	(49,439)	(45,364)	$ (64,300)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Narrative (Details) $ in Thousands		12 Months Ended
Income Taxes - Narrative (Details) $ in Thousands	Jan. 01, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Income Tax Disclosure [Abstract]
Effective tax rate		(0.07%)	0.53%	0.01%
Deferred tax assets, valuation allowance		$ 49,439	$ 45,364	$ 64,300
Decrease in deferred tax asset, valuation allowance			22,600
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards expiration		900
Unrecognized excess tax benefit	$ 1,600
Unrecognized tax benefits		10,973	10,200	$ 17,370	$ 14,130
Unrecognized tax benefits that impact effective tax rate		0
Federal
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards		172,300	172,900
Tax credit carryforwards		$ 8,800	7,100
State
Operating Loss Carryforwards [Line Items]
Impact of Tax Act in income tax rate (less than)		0.01
Operating loss carryforwards		$ 38,500	38,500
Tax credit carryforwards		$ 9,700	$ 8,300

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits—beginning balance	$ 10,200	$ 17,370	$ 14,130
Increase related to tax positions taken during prior year	108	0	0
Decrease related to tax positions taken during prior year	(2)	(7,739)	0
Increase related to tax positions taken during current year	667	569	3,240
Gross unrecognized tax benefits—ending balance	$ 10,973	$ 10,200	$ 17,370

Segment and Geographical Information - Narrative (Details)	12 Months Ended
	Dec. 31, 2018 segment
Segment Reporting [Abstract]
Number of operating segments	1
Number of reportable segments	1

Segment and Geographical Information - Revenue by Type (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Revenue	$ 253,354	$ 202,552	$ 164,445
Marketplace
Disaggregation of Revenue [Line Items]
Revenue	223,831	178,046	138,484
Managed services
Disaggregation of Revenue [Line Items]
Revenue	$ 29,523	$ 24,506	$ 25,961

Segment and Geographical Information - Geographic Area (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 253,354	$ 202,552	$ 164,445
Freelancers
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	163,242	132,066	113,371
Freelancers \| United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	40,313	26,596	21,455
Freelancers \| India
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	25,485	21,880	20,003
Freelancers \| Philippines
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	17,057	14,761	13,394
Freelancers \| Rest of world
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	80,387	68,829	58,519
Clients
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	90,112	70,486	51,074
Clients \| United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	65,578	55,179	42,455
Clients \| Rest of world
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 24,534	$ 15,307	$ 8,619

401(k) Plan (Details) - USD ($)	12 Months Ended
401(k) Plan (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Company matching cash contributions	50.00%
Maximum annual contributions per employee	$ 5,000
Expense for matching contributions	$ 1,700,000	$ 1,200,000	$ 900,000

Subsequent Events (Details) - USD ($) $ in Thousands	Feb. 28, 2019	Dec. 31, 2018
Subsequent Event [Line Items]
Minimum lease payments		$ 27,939
Lease payments, Year 1		4,683
Lease payments, Year 2		3,569
Lease payments, Year 3		4,914
Lease payments, Year 4		5,052
Lease payments, Year 5		$ 5,194
Subsequent Event
Subsequent Event [Line Items]
Minimum lease payments	$ 14,300
Subsequent Event \| Minimum
Subsequent Event [Line Items]
Lease payments, Year 1	1,400
Lease payments, Year 2	1,400
Lease payments, Year 3	1,400
Lease payments, Year 4	1,400
Lease payments, Year 5	1,400
Lease payments, Year 6	1,400
Lease payments, Year 7	1,400
Lease payments, Year 8	1,400
Lease payments, Year 9	1,400
Lease payments, Year 10	1,400
Subsequent Event \| Maximum
Subsequent Event [Line Items]
Lease payments, Year 1	1,800
Lease payments, Year 2	1,800
Lease payments, Year 3	1,800
Lease payments, Year 4	1,800
Lease payments, Year 5	1,800
Lease payments, Year 6	1,800
Lease payments, Year 7	1,800
Lease payments, Year 8	1,800
Lease payments, Year 9	1,800
Lease payments, Year 10	$ 1,800