Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2017	Feb. 12, 2018	Jun. 30, 2017
Document and Entity Information [Line Items]
Entity Registrant Name	APPIAN CORP
Entity Central Index Key	0001441683
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Amendment Flag	false
Trading Symbol	APPN
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Class A Common Stock
Document and Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		13,178,927
Entity Public Float			$ 130,453,125
Class B Common Stock
Document and Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		47,562,464
Entity Public Float			$ 187,610,252

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 73,758	$ 31,143
Accounts receivable, net of allowance of $400	55,315	46,814
Deferred commissions, current	9,117	7,146
Prepaid expenses and other current assets	7,032	3,281
Total current assets	145,222	88,384
Property and equipment, net	2,663	3,101
Deferred commissions, net of current portion	12,376	10,860
Deferred tax assets	281	12
Other assets	510	381
Total assets	161,052	102,738
Current liabilities
Accounts payable	5,226	5,057
Accrued expenses	6,467	2,860
Accrued compensation and related benefits	12,075	9,554
Deferred revenue, current	70,165	52,000
Current portion of long-term debt	0	6,111
Other current liabilities	1,182	437
Total current liabilities	95,115	76,019
Long-term debt, net of current portion	0	13,889
Deferred tax liabilities	87	32
Deferred revenue, net of current portion	18,922	18,108
Preferred stock warrant liability	0	850
Other long-term liabilities	1,404	1,917
Total liabilities	115,528	110,815
Stockholders’ equity (deficit)
Common stock	0	3
Additional paid-in capital	141,268	0
Accumulated other comprehensive income	439	1,330
Accumulated deficit	(96,189)	(64,825)
Total stockholders’ equity (deficit)	45,524	(63,492)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	161,052	102,738
Series A Convertible Preferred Stock
Convertible preferred stock
Preferred stock	0	17,915
Series B Convertible Preferred Stock
Convertible preferred stock
Preferred stock	0	37,500
Class A Common Stock
Stockholders’ equity (deficit)
Common stock	1	0
Class B Common Stock
Stockholders’ equity (deficit)
Common stock	$ 5	$ 0

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Allowance for doubtful accounts	$ 400	$ 400
Common stock, par value (in usd per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	0	61,462,320
Common stock, shares issued (in shares)	0	34,274,718
Common stock, shares outstanding (in shares)	0	34,274,718
Series A Convertible Preferred Stock
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	0	12,127,468
Preferred stock, shares issued	0	12,043,108
Preferred stock, shares outstanding	0	12,043,108
Series B Convertible Preferred Stock
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	0	6,120,050
Preferred stock, shares issued	0	6,120,050
Preferred stock, shares outstanding	0	6,120,050
Class A Common Stock
Common stock, par value (in usd per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	500,000,000	0
Common stock, shares issued (in shares)	13,030,081	0
Common stock, shares outstanding (in shares)	13,030,081	0
Class B Common Stock
Common stock, par value (in usd per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	100,000,000	0
Common stock, shares issued (in shares)	47,569,796	0
Common stock, shares outstanding (in shares)	47,569,796	0

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue:
Subscriptions, software and support	$ 25,398	$ 22,660	$ 22,012	$ 21,444	$ 19,365	$ 17,668	$ 17,321	$ 15,618	$ 91,514	$ 69,972	$ 53,207
Professional services	25,164	21,988	21,186	16,885	14,382	13,077	15,146	20,346	85,223	62,951	57,997
Total revenue	50,562	44,648	43,198	38,329	33,747	30,745	32,467	35,964	176,737	132,923	111,204
Cost of revenue:
Subscriptions, software and support	2,488	2,341	2,488	2,062	1,929	1,890	1,836	1,782	9,379	7,437	6,079
Professional services	16,169	14,272	14,149	10,628	8,670	9,315	11,723	12,978	55,218	42,686	42,402
Total cost of revenue	18,657	16,613	16,637	12,690	10,599	11,205	13,559	14,760	64,597	50,123	48,481
Gross profit	31,905	28,035	26,561	25,639	23,148	19,540	18,908	21,204	112,140	82,800	62,723
Operating expenses:
Sales and marketing	22,463	19,725	22,775	17,003	14,660	14,480	13,831	11,166	81,966	54,137	38,300
Research and development	8,968	8,596	9,971	7,300	6,069	6,702	5,296	4,927	34,835	22,994	16,750
General and administrative	7,429	6,237	8,635	4,849	4,260	4,531	4,318	3,930	27,150	17,039	12,515
Total operating expenses	38,860	34,558	41,381	29,152	24,989	25,713	23,445	20,023	143,951	94,170	67,565
Operating loss	(6,955)	(6,523)	(14,820)	(3,513)	(1,841)	(6,173)	(4,537)	1,181	(31,811)	(11,370)	(4,842)
Other (income) expense:
Other (income) expense, net	(380)	(425)	(734)	(499)	1,663	(67)	733	(537)	(2,038)	1,792	1,579
Interest expense	22	(2)	197	256	256	243	241	242	473	982	188
Total other expense (income)	(358)	(427)	(537)	(243)	1,919	176	974	(295)	(1,565)	2,774	1,767
Total	(6,597)	(6,096)	(14,283)	(3,270)	(3,760)	(6,349)	(5,511)	1,476	(30,246)	(14,144)	(6,609)
Income tax expense (benefit)	272	188	176	125	423	(1,610)	(1,217)	721	761	(1,683)	378
Net loss	$ (6,869)	$ (6,284)	$ (14,459)	$ (3,395)	$ (4,183)	$ (4,739)	$ (4,294)	$ 755	(31,007)	(12,461)	(6,987)
Accretion of dividends on convertible preferred stock									357	857	861
Net loss attributable to common stockholders									$ (31,364)	$ (13,318)	$ (7,848)
Net loss per share attributable to common stockholders:
Basic and diluted (in dollar per share)									$ (0.63)	$ (0.39)	$ (0.23)
Weighted average common shares outstanding:
Basic and diluted (in shares)									49,529,833	34,274,718	34,274,718

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net loss	$ (31,007)	$ (12,461)	$ (6,987)
Comprehensive loss, net of income taxes:
Foreign currency translation adjustment	(891)	359	159
Total other comprehensive loss, net of income taxes	$ (31,898)	$ (12,102)	$ (6,828)

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Restricted Stock Units	Restricted Stock Units Common Stock
Balance (in shares) at Dec. 31, 2014		34,274,718
Balance at Dec. 31, 2014	$ (42,844)	$ 3		$ 812	$ (43,659)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(6,987)				(6,987)
Accretion of dividends on convertible preferred stock	(861)				(861)
Other comprehensive loss	159			159
Balance (in shares) at Dec. 31, 2015		34,274,718
Balance at Dec. 31, 2015	(50,533)	$ 3		971	(51,507)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(12,461)				(12,461)
Accretion of dividends on convertible preferred stock	(857)				(857)
Other comprehensive loss	359			359
Balance (in shares) at Dec. 31, 2016		34,274,718
Balance at Dec. 31, 2016	(63,492)	$ 3		1,330	(64,825)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(31,007)				(31,007)
Accretion of dividends on convertible preferred stock	(357)				(357)
Conversion of convertible preferred stock to common stock (in shares)		18,163,158
Conversion of convertible preferred stock to common stock	48,207	$ 2	$ 48,205
Conversion of convertible preferred stock warrant to common stock warrant	1,191		1,191
Issuance of common stock from initial public offering, net of issuance costs (in shares)		7,187,500
Issuance of common stock from initial public offering, net of issuance costs	$ 77,789	$ 1	77,788
Exercise of common stock warrant (in shares)		79,363
Issuance of common stock to directors (in shares)		14,087
Vesting of restricted stock units (in shares)						4,930	4,930
Exercise of stock options (in shares)	876,121	876,121
Exercise of stock options	$ 1,108		1,108
Stock-based compensation expense	12,976		12,976
Other comprehensive loss	(891)			(891)
Balance (in shares) at Dec. 31, 2017		60,599,877
Balance at Dec. 31, 2017	$ 45,524	$ 6	$ 141,268	$ 439	$ (96,189)

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net loss	$ (31,007)	$ (12,461)	$ (6,987)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	886	764	763
Bad debt expense	62	7	(22)
Deferred income taxes	(251)	(1,122)	(291)
Stock-based compensation	12,976	0
Fair value adjustment for warrant liability	341	200	299
Loss on extinguishment of debt	384	0	0
Changes in assets and liabilities:
Accounts receivable	(9,716)	(11,154)	(6,639)
Prepaid expenses and other assets	(4,162)	(1,665)	(988)
Deferred commissions	(3,487)	(5,335)	(3,965)
Accounts payable and accrued expenses	4,128	1,287	1,058
Accrued compensation and related benefits	2,365	3,717	(968)
Other current liabilities	383	19	(251)
Deferred revenue	18,344	17,410	15,490
Other long-term liabilities	(374)	577	356
Net cash used in operating activities	(9,128)	(7,756)	(2,145)
Cash flows from investing activities:
Purchases of property and equipment	(433)	(984)	(524)
Net cash used in investing activities	(433)	(984)	(524)
Cash flows from financing activities:
Proceeds from initial public offering, net of underwriting discounts	80,213	0	0
Payment of initial public offering costs	(2,424)	0	0
Payment of dividend to Series A preferred stockholders	(7,565)	0	0
Proceeds from exercise of common stock options	1,108	0	0
Proceeds from issuance of long-term debt, net of debt issuance costs	19,616	20,000	10,000
Repayment of long-term debt	(40,000)	(10,000)	0
Net cash provided by financing activities	50,948	10,000	10,000
Effect of foreign exchange rate changes on cash and cash equivalents	1,228	(1,510)	(930)
Net increase (decrease) in cash and cash equivalents	42,615	(250)	6,401
Cash and cash equivalents, beginning of period	31,143	31,393	24,992
Cash and cash equivalents, end of period	73,758	31,143	31,393
Supplemental disclosure of cash flow information:
Cash paid for interest	515	895	193
Cash paid for income taxes	615	610	1,055
Supplemental disclosure of non-cash financing activities:
Accretion of dividends on convertible preferred stock	357	857	861
Conversion of Convertible Preferred Stock to Common Stock
Supplemental disclosure of non-cash financing activities:
Conversion of convertible stock	48,207	0	0
Conversion of Convertible Preferred Stock Warrant to Common Stock Warrant
Supplemental disclosure of non-cash financing activities:
Conversion of convertible stock	$ 1,191	$ 0	$ 0

Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Significant Accounting Policies

Basis of Presentation

The accompanying consolidated financial statements and footnotes have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) as contained in the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (the “Codification” or “ASC”).

Use of Estimates

The preparation of our consolidated financial statements in conformity with U.S. GAAP requires us to make estimates and judgments that affect the amounts reported in these consolidated financial statements and accompanying notes. Although we believe that the estimates we use are reasonable, due to the inherent uncertainty involved in making these estimates, actual results reported in future periods could differ from those estimates.

Significant estimates embedded in the consolidated financial statements include revenue recognition, income taxes and the related valuation allowance, stock-based compensation and fair value measurements for our common stock and preferred stock warrant.

Principles of Consolidation

The accompanying consolidated financial statements include the accounts of Appian and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.

Initial Public Offering

In May 2017, we completed an initial public offering, or IPO, in which we sold 7,187,500 shares of our newly-authorized Class A common stock at an initial price to the public of $12.00 per share. We received net proceeds of $77.8 million, after deducting underwriting discounts and commissions and offering expenses paid and payable by us, from sales of our shares in the IPO. Immediately prior to the completion of the IPO, (1) all shares of common stock then outstanding were converted into Class B common stock on a one-for-one basis, (2) a warrant to purchase shares of convertible preferred stock was converted into a warrant to purchase shares of Class B common stock and (3) all shares of convertible preferred stock then outstanding were converted into shares of our common stock on a one-for-one basis, and then reclassified as shares of Class B common stock. See Note 8 for further discussion of the convertible preferred stock and Note 9 for further discussion of the warrant.

Deferred offering costs of $2.4 million, consisting of legal, accounting and other fees and costs related to our IPO, were recorded to additional paid-in capital as a reduction of the proceeds upon the closing of our IPO.

Secondary Offering

In November 2017, we completed a secondary offering in which stockholders sold an aggregate of 4,370,000 shares of our Class A common stock at a price of $20.25 per share. We did not receive any proceeds from the sale of the shares of our Class A common stock offered in the secondary offering.

Revenue Recognition

We generate revenue primarily through sales of subscriptions to our platform, as well as professional services. We recognize revenue when all of the following conditions are met: (1) there is persuasive evidence of an arrangement; (2) the service or product has been provided to the customer; (3) the amount of fees to be paid by the customer is fixed or determinable; and (4) the collection of related fees is reasonably assured. If collection is not reasonably assured, we defer revenue recognition until collectability becomes reasonably assured. Our arrangements do not contain general rights of return. Revenue is recognized net of any taxes collected from customers and subsequently remitted to governmental authorities.

Subscriptions, Software and Support Revenue

Subscriptions, software and support revenue is primarily related to (1) software as a service (“SaaS”) subscriptions bundled with maintenance and support and hosting services and (2) term license subscriptions bundled with maintenance and support. To a lesser extent, we also generate revenue from the sale of perpetual software licenses and associated maintenance and support.

Historically, we licensed our software primarily under perpetual licenses, but over time we transitioned from perpetual licenses to subscriptions. As a result, revenue from our perpetual software licenses was less than 1.0% of our total revenue for 2017 and 2016, respectively, and 1.9% of our total revenue in 2015.

We generally charge subscription fees on a per-user basis. We bill customers and collect payment for subscriptions to our platform in advance on a monthly, quarterly or annual basis. In certain instances, we have had customers pay their entire contract up front.

SaaS Subscriptions

Our SaaS subscription revenue is derived from customers accessing our cloud offering pursuant to contracts that are generally one to five years in length. We perform all required maintenance and support for our cloud offering and we do not separately charge customers for hosting costs. In these arrangements, our customers do not have the right to take the software on-premises and, as a result, such arrangements are not accounted for within the scope of the software revenue guidance. Revenue from SaaS subscriptions is recognized ratably over the term of the subscription, beginning with the date our service is made available to our customer.

Term License Subscriptions

Our term license subscription revenue is derived from customers with on-premises installations of our platform pursuant to contracts that are generally one to five years in length. Customers with term license subscriptions have the right to use our software and receive maintenance and support. Since we do not sell maintenance and support separately from the subscription, revenue for the term license subscription and maintenance and support is recognized ratably over the term of the subscription, upon delivery of the platform to the customer when sold on a standalone basis.

Professional Services

Our professional services revenue is comprised of fees for consulting services, including application development and deployment assistance and training related to our platform. Our professional services are not essential to the functionality of our platform because the platform is ready for the customer’s use immediately upon delivery and is not modified or customized in any manner.

Consulting services are billed under both time-and-material and fixed-fee arrangements. For standalone time-and-material contracts, we recognize revenue at contractually agreed upon billing rates applied to hours performed. For standalone fixed-fee contracts, we also recognize revenue as the work is performed using the proportional performance method of accounting. Training revenue is recognized when the associated training services are delivered. Training is also sold in the form of a subscription arrangement where a customer agrees to pay an annual fixed fee for a fixed number of users to have access to all of our training offerings during the year. Revenue from training subscription agreements is recognized ratably over the subscription period.

We defer recognition of revenue from work performed on pending contract modifications until the period in which the modifications are accepted and funding is approved by the customer. Costs of work performed on pending contract modifications are expensed as incurred.

Multiple Element Arrangements

Our multiple element arrangements are from SaaS subscriptions and term license subscriptions that are generally sold in combination with maintenance and support service and frequently with professional services.

SaaS Subscriptions

For multiple element arrangements involving SaaS subscriptions that include professional services in addition to the subscription to our platform, we evaluate each element to determine whether it represents a separate unit of accounting. Because there are third-party vendors who routinely sell and provide the same professional services to our customers, our professional services are deemed to have standalone value apart from the SaaS subscription. Additionally, we offer both SaaS subscriptions and professional services on a standalone basis. Professional services revenue is therefore accounted for separately from subscription fees and recognized as the professional services are performed. We allocate revenue to the elements based on the selling price hierarchy using vendor-specific objective evidence (“VSOE”) of selling price, third-party evidence (“TPE”) of selling price, or if neither exists, best estimated selling price (“BESP”). In cases where we do not have VSOE or TPE of the elements of our arrangements, we use BESP to allocate revenue. We determine BESP for a service by considering multiple factors including, but not limited to, evaluating the weighted average of actual sales prices and other factors such as gross margin objectives, pricing practices and growth strategy. Pricing practices taken into consideration include historic contractually stated prices, volume discounts where applicable and our price lists. While we believe we can make reliable estimates regarding these matters, these estimates are inherently subjective. Once the revenue is allocated to these elements, revenue is recognized as such services are provided.

Term License Subscriptions

For multiple element arrangements involving term license subscriptions, maintenance and support and professional services, we do not have VSOE of fair value for the maintenance and support. Our term license subscriptions are generally not sold on a standalone basis, and therefore, we have not established VSOE of fair value for the subscriptions. Consequently, for our bundled arrangements that include certain professional services, there are two undelivered elements for which VSOE of fair value has not been established and, therefore, we utilize the combined services approach and defer all revenue until the software has been delivered and the provision of all services has commenced. We then recognize the entire fee from the arrangement ratably over the remaining period of the arrangement, assuming all other software revenue recognition criteria have been met.

Deferred Revenue

Deferred revenue primarily consists of amounts billed or billable in advance of revenue recognition from our subscriptions, software, and support and professional services described above. Deferred revenue is recognized as the revenue recognition criteria are met.

Cost of Revenue

Cost of Subscriptions, Software and Support Revenue

Cost of subscriptions, software and support revenue consists primarily of fees paid to our third-party managed hosting providers and other third-party service providers, personnel costs, including payroll and benefits for our technology operations and customer support teams, and allocated facility costs and overhead.

Cost of Professional Services Revenue

Cost of professional services revenue includes all direct and indirect costs to deliver our professional services and training, including employee compensation for our global professional services and training personnel, travel costs, third-party contractor costs and allocated facility costs and overhead.

Concentration of Credit Risk

Our financial instruments that are exposed to concentration of credit risk consist primarily of cash and cash equivalents and trade accounts receivable. Cash deposits may be in excess of insured limits. We believe that the financial institutions that hold our cash deposits are financially sound and, accordingly, minimal credit risk exists with respect to these balances.

With regard to our customers, credit evaluation and account monitoring procedures are used to minimize the risk of loss. We believe that no additional credit risk beyond amounts provided for collection loss are inherent in accounts receivable. Revenue generated from government agencies represented 15.4%, 26.2% and 32.7% of our revenue for the years ended December 31, 2017, 2016 and 2015, respectively, of which the top three federal government agencies generated 8.4%, 17.7% and 20.8% of our revenue for the years ended December 31, 2017, 2016 and 2015, respectively. Additionally, 27.0%, 19.5% and 19.9% of our revenue during the years ended December 31, 2017, 2016 and 2015, respectively, was generated from foreign customers.

One customer accounted for 7.0% and 17.2% of accounts receivable at December 31, 2017 and December 31, 2016, respectively.

Cash and Cash Equivalents

We consider all highly liquid investments with an original or remaining maturity of three months or less at the date of purchase, as well as overnight repurchase investments, to be cash equivalents.

Accounts Receivable and Allowance for Doubtful Accounts

Accounts receivable are stated at realizable value, net of an allowance for doubtful accounts. The allowance for doubtful accounts is based on our assessment of the collectability of accounts. We regularly review the composition of the accounts receivable aging, historical bad debts, changes in payment patterns, customer creditworthiness and current economic trends. If the financial condition of our customers were to deteriorate, resulting in their inability to make required payments, additional provisions for doubtful accounts would be required and would increase bad debt expense. To date, our allowance and related bad debt write-offs have been nominal. There was no change in the allowance for doubtful accounts from December 31, 2016 to December 31, 2017.

Deferred Commissions

Deferred commissions are the incremental costs that are directly associated with subscription agreements with customers and consist of sales commissions paid to our direct sales force. Commissions are considered direct and incremental and as such are deferred and amortized over the terms of the related customer contracts consistent with the related revenue. Amortization of deferred commissions is included in sales and marketing expense in the accompanying consolidated statements of operations. Commission expense was $11.8 million, $6.5 million and $4.6 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Property and Equipment

Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the assets. Significant additions or improvements extending the useful life of an asset are capitalized, while repairs and maintenance costs which do not significantly improve the related assets or extend their useful lives are charged to expense as incurred.



Asset Category		Useful Life (in years)
Computer software		3
Computer hardware		3
Equipment		5
Office furniture and fixtures		10
Leasehold improvements		Shorter of useful life of assets or lease term

Impairment of Long-Lived Assets

Long-lived assets and certain intangible assets are reviewed for impairment whenever events or circumstances indicate that the carrying amount of an asset may not be recoverable through undiscounted cash flows from the use of the assets. If such assets are considered to be impaired, the assets are written down to their estimated fair value. No indicators of impairment were identified for the years ended December 31, 2017, 2016 and 2015.

Fair Value of Financial Instruments

The carrying amounts of our cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate fair value as of December 31, 2017 and December 31, 2016 because of the relatively short duration of these instruments. The carrying value of our long-term debt as of December 31, 2016 approximated fair value given interest rates for similar debt instruments available to the Company.

We use a three-tier fair value hierarchy to classify and disclose all assets and liabilities measured at fair value on a recurring basis, as well as assets and liabilities measured at fair value on a non-recurring basis, in periods subsequent to their initial measurement. The hierarchy requires us to use observable inputs when available, and to minimize the use of unobservable inputs when determining fair value. The three tiers are defined as follows:


•	Level 1. Observable inputs based on unadjusted quoted prices in active markets for identical assets or liabilities;


•	Level 2. Inputs, other than quoted prices in active markets, that are observable either directly or indirectly; and


•	Level 3. Unobservable inputs for which there is little or no market data, which require us to develop our own assumptions.

Assets and Liabilities Measured at Fair Value on a Recurring Basis

We evaluate our financial assets and liabilities subject to fair value measurements on a recurring basis to determine the appropriate level in which to classify them for each reporting period. This determination requires significant judgments to be made. After the reclassification of the convertible preferred stock warrant in May 2017, we did not have any assets or liabilities subject to fair value measurements as of December 31, 2017. See Note 9 for further discussion of the warrant reclassification. The following table summarizes the conclusions reached as of December 31, 2016 (in thousands):



	December 31, 2016		Level 1		Level 2		Level 3
Liabilities:
Series A convertible preferred stock warrant(1)	$	850	$	—	$	—	$	850
	$	850	$	—	$	—	$	850

(1)

In order to determine the fair value of the convertible preferred stock warrant, we used the Black-Scholes option pricing model (“OPM”). Significant inputs for the OPM included an estimate of the fair value of the Series A convertible preferred stock, the remaining contractual life of the warrant, an estimate of the timing of a liquidity event, a risk-free rate of interest and an estimate of our stock volatility using the volatilities of guideline peer companies.

Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs

The following table presents the changes in our Level 3 instruments measured at fair value on a recurring basis during the years ended December 31, 2017, 2016 and 2015 (in thousands):



	Year Ended December 31,
	2017			2016		2015
Balance as of January 1,	$	850		$	650	$	351
Change in fair value of warrant liability	341			200		299
Reclassification of warrant liability to equity	(1,191		)	—		—
Balance as of December 31,	$	—		$	850	$	650

Stock-Based Compensation

We account for stock-based compensation expense related to stock-based awards based on the estimated fair value of the award on the grant date. We calculate the fair value of stock options using the Black-Scholes OPM. For service-based awards, stock-based compensation expense is recognized on a straight-line basis over the requisite service period. For performance-based awards, stock-based compensation expense is recognized using the accelerated attribution method, based on the probability of satisfying the performance condition. For awards that contain market conditions, compensation expense is measured using a Monte Carlo simulation model and recognized using the accelerated attribution method over the derived service period based on the expected market performance as of the grant date. For restricted stock units, stock-based compensation expense is recognized on a straight-line basis over the requisite service period. We account for forfeitures as they occur, rather than estimating expected forfeitures.

Basic and Diluted Loss per Common Share

We use the two-class method to compute net loss per common share because we have issued securities, other than common stock, that contractually entitle the holders to participate in dividends and earnings. These participating securities include our convertible preferred stock which have non-forfeitable rights to participate in any dividends declared on our common stock. The two-class method requires earnings for the period to be allocated between common stock and participating securities based upon their respective rights to receive distributed and undistributed earnings.

Under the two-class method, for periods with net income, basic net income per common share is computed by dividing the net income attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period. Net income attributable to common stockholders is computed by subtracting from net income the portion of current year earnings that the participating securities would have been entitled to receive pursuant to their dividend rights had all of the year’s earnings been distributed. No such adjustment to earnings is made during periods with a net loss, as the holders of the participating securities have no obligation to fund losses.

Diluted net income per common share is computed under the two-class method by using the weighted average number of shares of common stock outstanding, plus, for periods with net income attributable to common stockholders, the potential dilutive effects of stock options and warrants. In addition, we analyze the potential dilutive effect of the outstanding participating securities under the “if-converted” method when calculating diluted earnings per share, in which it is assumed that the outstanding participating securities convert into common stock at the beginning of the period or date of issuance, if later. We report the more dilutive of the approaches (two-class or “if-converted”) as our diluted net income per share during the period.

Due to net losses for the years ended December 31, 2017, 2016 and 2015, basic and diluted net loss per share were the same, as the effect of potentially dilutive securities would have been anti-dilutive.

Income Taxes

We use the asset and liability method of accounting for income taxes in which deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the consolidated financial statement carrying amounts of existing assets and liabilities and their respective tax bases. We measure deferred tax assets and liabilities using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be reversed. We recognize the effect on deferred tax assets and liabilities of a change in tax rates as income and expense in the period that includes the enactment date. A valuation allowance is established if it is more likely than not that all or a portion of the deferred tax asset will not be realized.

Our tax positions are subject to income tax audits by multiple tax jurisdictions throughout the world. We recognize the tax benefit of an uncertain tax position only if it is more likely than not the position is sustainable upon examination by the taxing authority. We measure the tax benefit recognized as the largest amount of benefit which is more likely than not to be realized upon settlement with the taxing authority. We recognize penalties and interest related to unrecognized tax benefits as income tax expense.

We calculate the current and deferred income tax provision based on estimates and assumptions that could differ from the actual results reflected in income tax returns filed in subsequent years and record adjustments based on filed income tax returns when identified. The amount of income taxes paid is subject to examination by U.S. federal, state and foreign tax authorities. The estimate of the potential outcome of any uncertain tax issue is subject to our assessment of relevant risks, facts and circumstances existing at that time. To the extent the assessment of such tax position changes, we record the change in estimate in the period in which we make that determination.

As described in more detail below under "Recent Accounting Pronouncements" and in Note 6, the Tax Cuts and Jobs Act (the “TCJA”) was enacted on December 22, 2017, substantially changing the U.S. federal tax system. We are required to complete our tax accounting for the TCJA in the period when it has obtained, prepared, and analyzed the information to complete the income tax accounting.

We have not completed our accounting for the tax effects of enactment of the TCJA; however, we have made reasonable estimates of the effects of the TCJA on our financial statements which are included as a component of income tax expense.

Segment Reporting

Operating segments are defined as components of an enterprise for which discrete financial information is available that is evaluated regularly by the chief operating decision maker (“CODM”) for purposes of allocating resources and evaluating financial performance. Our CODM is our chief executive officer, who reviews financial information presented on a companywide basis for purposes of allocating resources and evaluating financial performance. As such, our operations constitute a single operating segment and one reportable segment.

Foreign Currency

Our operations located outside of the United States where the local currency is the functional currency are translated into U.S. dollars using the current rate method. Results of operations are translated at the average rate of exchange for the period. Assets and liabilities are translated at the closing rates on the balance sheet date. Gains and losses on translation of these accounts are accumulated and reported as a separate component of stockholders’ deficit and other comprehensive income (loss).

Gains and losses on foreign currency transactions are recognized in the accompanying consolidated statements of operations as a component of other expense, net. Transaction gains and losses from transactions denominated in foreign currencies resulted in net transaction gains of $2.6 million for the year ended December 31, 2017 and net transaction losses of $1.5 million and $1.3 million for the years ended December 31, 2016 and 2015, respectively.

Research and Development

Research and development expenses include payroll, employee benefits, and other headcount-related costs associated with product development. Our product utilizes a common codebase, whether accessed by customers via the cloud or via an on-premises installation. Since our software is sold and licensed externally, we consider our software as external-use software for purposes of applying the capitalized software development guidance. Product development costs are expensed as incurred until technological feasibility has been established, which we define as the completion of all planning, designing, coding and testing activities that are necessary to establish products that meet design specifications including functions, features and technical performance requirements. We have determined that technological feasibility for our software products is reached shortly before they are released for sale. Costs incurred after technological feasibility is established are not significant, and accordingly we expense all research and development costs when incurred.

Advertising

We expense advertising costs as they are incurred. Advertising expenses were $3.0 million, $1.4 million and $0.5 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Emerging Growth Company Status

We are an “emerging growth company” as defined in the Jumpstart Our Business Startups Act (“JOBS Act”). The JOBS Act provides that an emerging growth company can take advantage of an extended transition period for complying with new or revised accounting standards. Thus, an emerging growth company can delay the adoption of certain accounting standards until those standards would otherwise apply to private companies. We have elected to avail ourselves of this extended transition period and, as a result, we will not adopt new or revised accounting standards on the relevant dates on which adoption of such standards is required for other public companies.

Recent Accounting Pronouncements

Adopted

On December 22, 2017, the TCJA was enacted, substantially changing the U.S. Federal tax system. Notable provisions of the TCJA include the reduction of the corporate tax rate from 35% to 21% beginning in 2018, the imposition of a one-time transition tax on unremitted cumulative non-U.S. earnings of foreign subsidiaries, and the implementation of a territorial tax system. While the changes from the TCJA are generally effective beginning in 2018, U.S. GAAP accounting for income taxes requires the effect of a change in tax laws or rates to be recognized in income from continuing operations for the period that includes the enactment date. Due to the complexities involved in accounting for the enactment of the TCJA, the Securities and Exchange Commission Staff Accounting Bulletin No. 118 (“SAB 118”) allows us to record provisional amounts in earnings for the year ending December 31, 2017. Where reasonable estimates can be made, the provisional accounting should be based on such estimates. When no reasonable estimate can be made, the provisional accounting may be based on the tax law in effect before the TCJA. We are required to complete our tax accounting for the TCJA in the period when we have obtained, prepared, and analyzed the information to complete the income tax accounting. We have not completed our accounting for the tax effects of enactment of the TCJA; however, we have made reasonable estimates of the effects of the TCJA on our consolidated financial statements which are included as a component of income tax expense.

Not Yet Adopted

In May 2014, the FASB issued ASU No. 2014-9, Revenue from Contracts with Customers (Topic 606)(“ASU 2014-9”), which provides new guidance for revenue recognition. ASU 2014-9 provides that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-9 also requires improved disclosures to help users of financial statements better understand the nature, amount, timing, and uncertainty of revenue that is recognized. Entities have the option of using either a full retrospective or modified retrospective approach for the adoption of the standard. In March 2016, the FASB issued ASU No. 2016-8, Principal Versus Agent Considerations (Reporting Revenue Gross Versus Net) (“ASU 2016-8”), which clarifies implementation guidance on principal versus agent considerations in ASU 2014-9. In April 2016, the FASB issued ASU No. 2016-10, Identifying Performance Obligations and Licensing (“ASU 2016-10”), which clarifies the identification of performance obligations and the licensing implementation guidance in ASU 2014-9. In addition, in May 2016, the FASB issued ASU No. 2016-12, Narrow-Scope Improvements and Practical Expedients (“ASU 2016-12”), which clarifies the guidance on assessing collectibility, presentation of sales taxes, noncash consideration and completed contracts and contract modifications at transition. For public entities, the new standard is effective for annual periods and interim periods within those annual periods, beginning after December 15, 2017. For all other entities, the new standard is effective for annual periods beginning after December 15, 2018, and interim periods within those annual periods beginning after December 15, 2019. We intend to avail ourselves of the JOBS Act extended transition period that permits us to defer adoption until January 1, 2019. We are currently evaluating the impact the adoption of these standards will have on our consolidated financial statements.

We currently plan to adopt the new standard using the full retrospective approach; however, the decision regarding the adoption method has not been finalized. Our final determination will depend on a number of factors such as the significance of the impact of the new standard on our financial results, system readiness, including that of software procured from third-party providers, and our ability to accumulate and analyze the information necessary to assess the impact on prior period financial statements, as necessary.

We continue to evaluate the impact of the new standard on our accounting policies, processes, and system requirements. We have assigned internal resources in addition to the engagement of third-party service providers to assist in the evaluation. Furthermore, we have made and will continue to make investments in systems to enable timely and accurate reporting under the new standard. While we continue to assess all potential impacts under the new standard there is the potential for significant impact to the timing of recognition of revenue, particularly term license subscriptions and professional services revenue. We also expect an impact to our accounting for contract acquisition costs, both with respect to the amounts that will be capitalized as well as the period of amortization.

Under current industry-specific software revenue recognition guidance, we have historically concluded that we did not have VSOE of fair value of the undelivered services related to term license subscriptions, and accordingly, have recognized term license subscriptions and related services ratably over the subscription term. Professional services included in an arrangement with subscription revenue has also been recognized ratably over the subscription term. The new standard, which does not retain the concept of VSOE, requires an evaluation of whether term license subscriptions and related services, including professional services, are distinct performance obligations and therefore should be separately recognized at a point in time or over time. Depending on the outcome of our evaluation, the timing of when revenue is recognized could change significantly for term license subscriptions and professional services under the new standard.

In February 2016, the FASB issued ASU No. 2016-2, Leases (Topic 842) (“ASU 2016-2”), which requires that lessees recognize assets and liabilities for leases with lease terms greater than 12 months in the statement of financial position. ASU 2016-2 also requires improved disclosures to help users of financial statements better understand the amount, timing and uncertainty of cash flows arising from leases. The update is effective for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020. Early adoption is permitted. We are currently evaluating the impact the adoption of ASU 2016-2 will have on our consolidated financial statements.

In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”), which aims to reduce the existing diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows. ASU 2016-15 will require adoption on a retrospective basis unless it is impracticable to apply, in which case we would be required to apply the amendments prospectively as of the earliest date practicable. ASU 2016-15 is effective for fiscal years beginning after December 15, 2018, and interim periods within fiscal years beginning after December 15, 2019. Early adoption is permitted. We are currently in the process of evaluating the impact of adoption of this standard on our consolidated financial statements.

In May 2017, the FASB issued ASU No. 2017-09, Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting ("ASU 2017-09"), which clarifies when a change to the terms or conditions of a share-based payment award must be accounted for as a modification. ASU 2017-09 requires modification accounting if the fair value, vesting condition or the classification of the award is not the same immediately before and after a change to the terms and conditions of the award. ASU 2017-09 will be effective on a prospective basis beginning on January 1, 2018. Early adoption is permitted. We do not expect ASU 2017-09 to have an impact on our consolidated financial statements.

Debt	12 Months Ended
Debt	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt	Debt 2015 Line of Credit At December 31, 2015, we had a $10.0 million revolving line of credit with a lender, expiring in June 2016, which was subsequently amended in June 2016 to extend the maturity date through June 2017. This line of credit was terminated in April 2017. 2015 Term Loan In March 2015, we entered into a collateralized $10.0 million term loan facility with a lender, maturing in March 2019, and borrowed the full amount under the term loan facility in June 2015. In January 2016, we paid off the outstanding balance of the term loan and simultaneously entered into a collateralized $20.0 million term loan facility, maturing in January 2020. We borrowed the full amount under the term loan facility in January 2016, which we repaid in full in April 2017. 2017 Financing Facility In April 2017, we entered into a new financing facility consisting of a $5.0 million senior revolving credit facility, a $20.0 million senior term loan, and a $10.0 million subordinated term loan. In connection with the execution of this financing facility, the prior line of credit was terminated, and we borrowed the full $20.0 million available under the senior term loan and repaid the outstanding balance under our prior term loan. Additionally, in connection with the execution of our new financing facility, the lender waived the prepayment fee associated with our prior line of credit. In June 2017, we used proceeds from our IPO to pay all remaining outstanding principal and interest under the senior term loan and subsequently terminated the senior term loan and subordinated term loan. In connection with the repayment of the senior term loan, we recognized a loss on extinguishment of debt of $0.4 million related to unamortized debt issuance costs, which is included within other (income) expense, net in the accompanying consolidated statements of operations. This financing facility was terminated in November 2017 in connection with our entry into a new $20.0 million revolving line of credit. 2017 Line of Credit In November 2017, we entered into a $20.0 million revolving line of credit with a lender. The facility matures in November 2022. We may elect whether amounts drawn on the revolving line of credit bear interest at a floating rate per annum equal to either the LIBOR or the prime rate plus an additional interest rate margin that is determined by the availability of the borrowings under the revolving line of credit. The additional interest rate margin will range from 2.00% to 2.50% in the case of LIBOR advances and from 1.00% to 1.50% in the case of prime rate advances. The revolving line of credit contains an unused facility fee in an amount between 0.15% and 0.25% of the average unused portion of the revolving line of credit, which is payable quarterly. The agreement contains certain customary affirmative and negative covenants and requires us to maintain (1) an adjusted quick ratio of at least 1.35 to 1.0 and (ii) minimum adjusted EBITDA, in the amounts and for the periods set forth in the agreement. Any amounts borrowed under the credit facility are collateralized by substantially all of our assets. We were in compliance with all covenants as of December 31, 2017. As of December 31, 2017, we had no outstanding borrowings under the revolving line of credit.

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Taxes

For the years ended December 31, 2017, 2016 and 2015, our net loss before income taxes was comprised of the following (in thousands):



	2017			2016			2015
Domestic	$	(23,093	)	$	(4,524	)	$	1,079
Foreign	(7,153		)	(9,620		)	(7,688		)
Total	$	(30,246	)	$	(14,144	)	$	(6,609	)

For the years ended December 31, 2017, 2016 and 2015, our income tax expense (benefit) was comprised of the following (in thousands):



	2017			2016			2015
Current:
Federal	$	(65	)	$	(627	)	$	390
State	68			(200		)	62
Foreign	1,009			266			217
Total current expense (benefit)	1,012			(561		)	669
Deferred:
Federal	(42		)	(922		)	(334		)
State	—			(230		)	43
Foreign	(209		)	30			—
Total deferred expense (benefit)	(251		)	(1,122		)	(291		)
Total income tax expense (benefit)	$	761		$	(1,683	)	$	378

On December 22, 2017, U.S. federal tax reform was enacted with the signing of the TCJA. Notable provisions of the TCJA include the following:


•	Establishment of a flat corporate income tax rate of 21% on U.S. earnings;


•	Imposition of a one-time tax on unremitted cumulative non-U.S. earnings of foreign subsidiaries, or the Transition Tax;


•	The imposition of a new minimum tax on certain non-U.S. earnings, irrespective of the territorial system of taxation, and generally allows for the repatriation of future earnings of foreign subsidiaries without incurring additional U.S. taxes by transitioning to a territorial system of taxation;


•	Imposition of minimum taxes on certain payments made by a U.S. company to a related foreign company, or the Base Erosion Anti-Abuse Tax;


•	Elimination of the alternative minimum tax and allowance of a refund for previous alternative minimum tax credits;


•	Allowance for immediate expensing of the cost of investments in certain depreciable assets acquired and placed in service after September 27, 2017; and


•	Reduction in tax deductions with respect to certain compensation paid to certain executive officers.

While the changes from the TCJA are generally effective beginning in 2018, U.S. GAAP accounting for income taxes requires the effect of a change in tax laws or rates to be recognized in income from continuing operations for the period that includes the enactment date. Due to the complexities involved in accounting for the enactment of the TCJA, the Securities and Exchange Commission Staff Accounting Bulletin No. 118 (“SAB 118”) allows us to record provisional amounts in earnings for the year ending December 31, 2017. Where reasonable estimates can be made, the provisional accounting should be based on such estimates. When no reasonable estimate can be made, the provisional accounting may be based on the tax law in effect before the TCJA. We are required to complete our tax accounting for the TCJA in the period when we have obtained, prepared, and analyzed the information to complete the income tax accounting.

We have not completed our accounting for the tax effects of enactment of the TCJA; however, as described below, we have made reasonable estimates of the effects of the TCJA on our consolidated financial statements which are included as a component of income tax expense:

•

Deferred tax assets and liabilities: U.S. deferred tax assets and liabilities were remeasured based on the rates at which they are expected to reverse in the future, which is generally 21.0%, resulting in an income tax expense of approximately $2.1 million. This expense is fully offset by the tax benefit from the reduction in our U.S. valuation allowance. We will continue to analyze certain aspects of the TCJA which could potentially affect the tax basis of the reported amounts. Additionally, our U.S. tax returns for 2017 will be filed during the fourth quarter of 2018 and any changes to the tax positions for temporary differences compared to the estimates used will result in an adjustment of the estimated tax expense recorded as of December 31, 2017.

•

Transition Tax effects: The Transition Tax is based on our total post-1986 earnings and profits that was previously deferred from U.S. income taxes. Our provisional estimate for the Transition Tax is zero because we have post-1986 accumulated deficits. We will continue to evaluate the TCJA and any future guidance from the U.S. Treasury Department and Internal Revenue Service (“IRS”) in the determination of the Transition Tax which could result in adjustment of the estimate recorded as of December 31, 2017.

•

Indefinite reinvestment: Following enactment of the TCJA and the associated Transition Tax, in general, repatriation of cash to the United States can be completed with no incremental U.S. tax; however, repatriation of cash could subject the Company to non-U.S. jurisdictional taxes on distributions. The cash that our non-U.S. subsidiaries hold for indefinite reinvestment is generally used to finance foreign operations and investments, including acquisitions. The income taxes applicable to such earnings are not readily determinable given the various tax planning strategies we could employ if we repatriated these earnings. We will continue to evaluate the impact of the TCJA on our election to indefinitely reinvest our non-U.S. earnings, if any.

We will continue to analyze the effects of the TCJA on our consolidated financial statements and operations. Additional impacts from the enactment of the TCJA will be recorded as they are identified during the measurement period as provided for in SAB 118, which allows measurement period adjustments up to one year from the enactment date.

For the years ended December 31, 2017, 2016 and 2015, the provision for income taxes differs from the amount computed by applying the federal statutory income tax rates to our loss before the provision (benefit) for income taxes, as follows:



	2017		2016		2015
U.S. federal statutory tax rate	34.0	%	34.0	%	34.0	%
State tax expense	4.9		1.4		(0.9	)
Foreign rate differential	(6.7	)	(17.8	)	(29.4	)
Nondeductible expenses	(0.9	)	(2.3	)	(4.1	)
Tax credits	5.8		6.5		10.0
Unrecognized tax benefits	(0.7	)	(0.2	)	(1.8	)
Other	(0.3	)	(0.2	)	(1.9	)
Remeasurement of deferred taxes	(7.0	)	—		—
Change in valuation allowance	(31.6	)	(9.6	)	(11.5	)
Total	(2.5	)%	11.8	%	(5.6	)%

Deferred tax assets and liabilities reflect the net tax effects of temporary differences between the carrying amount of the assets and liabilities for financial reporting purposes and the amounts used for income tax purposes.

As of December 31, 2017 and 2016, significant components of our deferred tax assets and liabilities were as follows (in thousands):



	2017			2016
Deferred tax assets:
Accrued vacation	$	967		$	529
Bad debt	109			159
Deferred revenue	1,248			2,176
Deferred rent	473			834
Tax credits	4,169			2,401
Net operating losses	10,413			2,939
Equity compensation	1,207			—
Other	287			929
Gross deferred tax assets	18,873			9,967
Less: Valuation allowance	(12,328		)	(2,642		)
Total deferred tax assets	6,545			7,325
Deferred tax liabilities:
Depreciation	(174		)	(349		)
Unbilled receivables	(555		)	(491		)
Prepaid expenses	(5,614		)	(6,505		)
Other	(8		)	—
Total deferred tax liabilities	(6,351		)	(7,345		)
Net deferred tax asset (liability)	$	194		$	(20	)

As of December 31, 2017 and 2016, we had $25.3 million and $1.8 million of gross net operating loss (“NOL”) carryforwards for U.S. federal tax purposes, respectively. Federal NOL carryforwards will expire, if unused, in 2037. As of December 31, 2017 and 2016, we had U.S. gross state NOL carryforwards of $25.3 million and $1.7 million, respectively. We had tax effected state NOL carryforwards of $1.6 million and $0.1 million as of December 31, 2017 and 2016, respectively. U.S. state NOL carryforwards will substantially expire, if unused, in 2037. As of December 31, 2017 and 2016, we had foreign NOL carryforwards of $35.7 million and $23.7 million, respectively, primarily attributable to our subsidiary in Switzerland. Those NOL carryforwards will substantially expire, if unused, in 2024.

Section 382 of the Internal Revenue Code limits the utilization of the NOLs when ownership changes occur, as defined by that section. A number of states have similar state laws that limit utilization of the state NOLs when ownership changes occur. We have performed an analysis of our Section 382 ownership changes and have determined that all federal and U.S state NOLs are available for use as of December 31, 2017.

As of December 31, 2017 and 2016, we had $4.5 million and $2.8 million, respectively, of federal tax credit carryforwards which will expire, if unused, in 2037.

The net change during the year in the total valuation allowance was $9.7 million, primarily driven by the valuation allowance recorded against the U.S. deferred tax assets and the change in the Switzerland deferred tax assets.

We continue to maintain a full valuation allowance against U.S. deferred tax assets based on our cumulative operating results as of December 31, 2017, three-year cumulative loss, and assessment of our expected future results of operations. We have evaluated all evidence, both positive and negative, in assessing the likelihood of realizability and the negative evidence outweighed the positive evidence.

As of December 31, 2017, we have a valuation allowance of $3.5 million against foreign deferred tax assets, primarily for deferred tax assets at our subsidiary in Switzerland. We continue to maintain a full valuation allowance on the deferred tax assets of our subsidiary in Switzerland as we determined that it was not more likely than not that we would be able to realize a benefit from the NOL at that subsidiary. Based on our cumulative operating results as of December 31, 2017, and assessment of our expected future results of operations, we determined that it was not more likely than not that we would be able to realize the deferred tax assets prior to expiration.

We are subject to income taxes in the United States, Australia, Canada, France, Germany, Italy, Netherlands, Switzerland, and United Kingdom.

Undistributed earnings of our foreign subsidiaries are considered to be indefinitely reinvested; accordingly, no U.S. income taxes have been provided thereon. Upon repatriation of those earnings, if any, we would be subject to U.S. income taxes, net of any applicable foreign tax credits, and foreign withholding taxes. Determination of the amount of unrecognized deferred U.S. income tax liability is not practicable.

As of December 31, 2017 and 2016, we had unrecognized tax benefits of $0.7 million and $0.4 million, respectively, of which the entire portion would affect our effective tax rate if recognized. The following table summarizes the activity related to our unrecognized tax benefit from December 31, 2014 to December 31, 2017 (in thousands):



Balance as of December 31, 2014	$	286
Additions for tax positions in current years	98
Additions for tax positions in prior years	—
Reductions due to lapse in statutes of limitations	—
Settlements	—
Balance as of December 31, 2015	384
Additions for tax positions in current years	171
Additions for tax positions in prior years	—
Reductions due to lapse in statutes of limitations	(136		)
Settlements	—
Balance as of December 31, 2016	419
Additions for tax positions in current years	232
Additions for tax positions in prior years	—
Reductions due to lapse in statutes of limitations	—
Settlements	—
Balance as of December 31, 2017	$	651

We recognize interest and penalties related to uncertain tax positions in income tax expense. During the year ended December 31, 2017, we reduced our liability for potential interest and penalties by $2,000. During the years ended December 31, 2016 and 2015, we recognized potential interest and penalties of $2,000 and $19,000, respectively, and the cumulative balance of interest and penalties as of December 31, 2017 and 2016 and was $33,000 and $35,000, respectively.

We anticipate that total unrecognized tax benefits will not decrease over the next year.

We file income tax returns in the United States federal jurisdiction and in many state and foreign jurisdictions. The tax years 2014 through 2017 remain open to examination by the major taxing jurisdictions to which we are subject. No material examinations are currently open.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2017

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

Stock-Based Compensation

In May 2017, our board of directors adopted, and our stockholders approved, the 2017 Equity Incentive Plan (the “2017 Plan”), which became effective as of the date of the final prospectus for our IPO. The 2017 Plan provides for the grant of incentive stock options to employees, and for the grant of nonstatutory stock options, restricted stock awards, restricted stock unit awards, stock appreciation rights, performance-based stock awards and other forms of equity compensation to employees, including officers, and to non-employee directors and consultants. We initially reserved 6,421,442 shares of Class A common stock for issuance under the 2017 Plan, which included 421,442 shares that remained available for issuance under our 2007 Stock Option Plan (the “2007 Plan”) at the time that the 2017 Plan became effective. The number of shares reserved under the 2017 Plan increases for any shares subject to outstanding awards originally granted under the 2007 Plan that expire or are forfeited prior to exercise. As a result of the adoption of the 2017 Plan, no further grants may be made under the 2007 Plan. As of December 31, 2017, there were 6,538,262 shares of Class A common stock reserved for issuance under the 2017 Plan, of which 5,775,770 were available to be issued.

The 2007 Plan provided for the grant of stock options to employees, directors, and officers. Options under the 2007 Plan are exercisable into shares of Class B common stock and generally expire ten years from the date of grant. Under the 2007 Plan, the exercise price of each award was established by the board of directors, but could not be less than the fair market value of a share of our common stock on the grant date. Options generally vest upon the satisfaction of both a service condition and a performance condition. The service condition is satisfied at various rates as determined by us, typically on an annual basis over five years. The performance condition required the occurrence of a qualifying event, defined as a change of control transaction or upon the completion of an IPO. The performance condition was satisfied upon the effectiveness of our IPO in May 2017, on which date we recognized $6.2 million of cumulative stock-based compensation expense using the accelerated attribution method from the service start date.

We estimate the fair value of stock options using the Black-Scholes OPM, which requires the use of subjective assumptions, including the expected term of the option, the current price of the underlying stock prior to our IPO, the expected stock price volatility, expected dividend yield and the risk-free interest rate for the expected term of the option. The expected term represents the period of time the stock options are expected to be outstanding. Due to the lack of sufficient historical exercise data to provide a reasonable basis upon which to otherwise estimate the expected term of the stock options, we use the simplified method to estimate the expected term for our stock options. Under the simplified method, the expected term of an option is presumed to be the mid-point between the vesting date and the end of the contractual term. Expected volatility is based on historical volatilities for publicly traded stock of comparable companies over the estimated expected term of the stock options. We assume no dividend yield because dividends are not expected to be paid in the near future, which is consistent with our history of not paying dividends.

The following table summarizes the assumptions used to estimate the fair value of stock options granted during the years ended December 31:



	2017	2016	2015
Risk-free interest rate	1.9% - 2.2%	1.3% - 1.5%	1.7% - 1.9%
Expected term (in years)	6.5	6.5	6.5
Expected volatility	38.1% - 40.6%	40.9% - 42.0%	39.7% - 44.4%
Expected dividend yield	—%	—%	—%

Stock Options

The following table summarizes the stock option activity for the year ended December 31, 2017:



	Number of Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value (in thousands)
Outstanding at January 1, 2017	6,784,448		$	4.65	6.5	$	44,259
Granted	1,256,200		11.92
Exercised	(876,121	)	1.27			14,807
Canceled	(153,640	)	7.29
Outstanding at December 31, 2017	7,010,887		6.36		6.6	176,122
Exercisable at December 31, 2017	2,800,447		2.07		3.9	82,367

The weighted average grant-date fair value of options granted during the year ended December 31, 2017, 2016 and 2015 was $5.05, $4.35 and $2.61 per share, respectively. The total fair value of stock options that vested during the year ended December 31, 2017 was $5.6 million. No stock options vested during the years ended December 31, 2016 and 2015 because a qualifying event had not yet occurred. As of December 31, 2017, the total compensation cost related to unvested stock options not yet recognized was $11.0 million, which will be recognized over a weighted average period of 2.8 years.

On April 25, 2017, our board of directors modified certain outstanding stock options nearing their expiration date to remove the performance condition. Stock options to purchase an aggregate of 216,160 shares of common stock were modified, and we recognized stock-based compensation expense of $2.4 million related to this modification.

Restricted Stock Units

The following table summarizes the restricted stock unit activity for the year ended December 31, 2017:



	Number of Shares		Weighted Average Grant Date Fair Value
Non-vested outstanding at January 1, 2017	—		$	—
Granted	738,055		22.15
Vested	(4,930	)	20.24
Canceled	(1,150	)	21.40
Non-vested outstanding at December 31, 2017	731,975		22.16

As of December 31, 2017, total unrecognized compensation cost related to unvested restricted stock units was approximately $15.6 million and the weighted average remaining vesting period was 2.8 years.

The following table summarizes the components of our stock-based compensation expense for the year ended December 31, 2017 (in thousands):



	2017
Stock-based compensation expense related to stock option modifications	$	2,394
Cumulative stock-based compensation expense related to stock options recorded upon effectiveness of our IPO	6,236
Post-IPO stock-based compensation expense related to stock options	3,371
Stock-based compensation expense related to the issuance of common stock to directors	222
Stock-based compensation expense related to restricted stock units	753
Total stock-based compensation expense	$	12,976

Stock-based compensation expense for restricted stock units, stock options and issuances of common stock is included in the following line items in the accompanying consolidated statements of operations for the year ended December 31, 2017 (in thousands):



	2017
Cost of revenue
Subscriptions, software and support	$	575
Professional services	1,295
Operating expenses
Sales and marketing	3,233
Research and development	2,822
General and administrative	5,051
Total stock-based compensation expense	$	12,976

For the years ended December 31, 2016 and 2015, no stock-based compensation expense was recognized for our stock option awards because a qualifying event had not yet occurred.

Convertible Preferred Stock and Stockholders’ Equity (Deficit)

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Convertible Preferred Stock and Stockholders’ Equity (Deficit)

Convertible Preferred Stock

Immediately prior to the completion of the IPO, all shares of convertible preferred stock then outstanding were automatically converted into 18,163,158 shares of common stock on a one-for-one basis, and then reclassified as shares of Class B common stock.

Summary of Activity

The following tables present a summary of activity for our convertible preferred stock issued and outstanding for the years ended December 31, 2017, 2016 and 2015 (dollar amounts in thousands):



	Series A Convertible Preferred Stock					Series B Convertible Preferred Stock
	Amount			Shares		Amount			Shares
Balance as of January 1, 2015	$	16,197		12,043,108		$	37,500		6,120,050
Accretion of dividends on convertible preferred stock	861			—		—			—
Balance as of December 31, 2015	$	17,058		12,043,108		$	37,500		6,120,050
Accretion of dividends on convertible preferred stock	857			—		—			—
Balance as of December 31, 2016	$	17,915		12,043,108		$	37,500		6,120,050
Accretion of dividends on convertible preferred stock	357			—		—			—
Payment of accrued dividend to Series A convertible preferred stockholders	(7,565		)	—		—			—
Conversion of convertible preferred stock to common stock	(10,707		)	(12,043,108	)	(37,500		)	(6,120,050	)
Balance as of December 31, 2017	$	—		—		$	—		—

Common Stock

Immediately prior to the completion of the IPO, all shares of common stock then outstanding were converted into Class B common stock on a one-for-one basis. We offered and sold newly authorized shares of Class A common stock in the IPO.

The rights of the holders of Class A common stock and Class B common stock are identical, except with respect to voting and conversion rights. The holders of Class A common stock are entitled to one vote per share, and the holders of Class B common stock are entitled to ten votes per share, on all matters that are subject to stockholder vote. The holders of Class B common stock also have approval rights for certain corporate actions. Each share of Class B common stock may be converted into one share of Class A common stock at the option of its holder and will be automatically converted into one share of Class A common stock upon transfer thereof, subject to certain exceptions. In addition, upon the date on which the outstanding shares of Class B common stock represent less than 10% of the aggregate voting power of our capital stock, all outstanding shares of Class B common stock shall convert automatically into Class A common stock.

Basic and Diluted Loss per Common Share

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Basic and Diluted Loss per Common Share

The following table sets forth the computation of basic and diluted net loss per share for the years ended December 31 (in thousands, except per share data):



	Year Ended December 31,
	2017			2016			2015
Numerator:
Net loss	$	(31,007	)	$	(12,461	)	$	(6,987	)
Accretion of dividends on convertible preferred stock	357			857			861
Net loss attributable to common stockholders	$	(31,364	)	$	(13,318	)	$	(7,848	)
Denominator
Weighted average common shares outstanding, basic and diluted	49,529,833			34,274,718			34,274,718
Net loss per share attributable to common stockholders, basic and diluted	$	(0.63	)	$	(0.39	)	$	(0.23	)

The following securities have been excluded from the calculation of weighted average common shares outstanding because the effect is anti-dilutive or performance or market conditions had not been met at the end of the period:



	Year Ended December 31,
	2017	2016	2015
Convertible preferred stock:
Series A convertible preferred stock	—	12,043,108	12,043,108
Series B convertible preferred stock	—	6,120,050	6,120,050
Warrant to purchase Series A convertible preferred stock	—	84,360	84,360
Stock options	7,010,887	6,784,448	4,589,988
Restricted stock units	731,975	—	—

Commitments and Contingencies

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Operating Leases

We lease office space and equipment in our headquarters location in Reston, Virginia, as well as in the United Kingdom, France, Germany, Canada, Italy, Australia and the Netherlands, under non-cancellable operating lease agreements which have various expiration dates through 2026 for our office space and various expiration dates through 2019 for our equipment.

A summary of our future minimum lease commitments by year as of December 31, 2017 is as follows (in thousands):



	Office Leases		Equipment Leases
2018	$	7,722	$	405
2019	8,043		216
2020	4,828		22
2021	2,503		—
2022	380		—
Thereafter	1,046		—
Total	$	24,522	$	643

We record rent expense using the total minimum rent commitment, amortized using the straight-line method over the term of the lease. The difference between monthly rental payments and recorded rent expense is charged to deferred rent. As of December 31, 2017 and 2016, deferred rent totaled $2.0 million and $2.4 million, respectively, and is included within other current liabilities and other long-term liabilities on the accompanying consolidated balance sheets.

In September 2014, we entered into an agreement to sublease a certain rented facility to a subtenant. The sublease agreement commenced on November 1, 2014 and expired when the original lease agreement expired in October 2017. We received $0.5 million for the year ended December 31, 2017 and $0.6 million for each of the years ended December 31, 2016 and 2015 in rental income from the subtenant.

Total rent and lease expense was $7.0 million, $6.6 million and $4.6 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Other Commitments

We also have entered into a non-cancellable agreement for the use of technology that is integral in the development of our software and pay annual royalty fees of $0.3 million.

Letters of Credit

As of December 31, 2017 and 2016, we had outstanding letters of credit totaling $1.1 million and $1.3 million, respectively, in connection with securing our leased office space. All letters of credit are secured by our borrowing arrangement as described in Note 5.

Legal

From time to time, we are subject to legal, regulatory and other proceedings and claims that arise in the ordinary course of business. There are no issues or resolution of any matters that are expected to have a material adverse impact on our consolidated financial statements.

Segment and Geographic Information

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Segment and Geographic Information

The following table summarizes revenue by geography for the years ended December 31 (in thousands):



	2017		2016		2015
Domestic	$	128,997	$	107,069	$	89,043
International	47,740		25,854		22,161
Total	$	176,737	$	132,923	$	111,204

With respect to geographic information, revenue is attributed to respective geographies based on the contracting address of the customer. There were no individual foreign countries from which more than 10% of our total revenue was attributable for the years ended December 31, 2017, 2016 and 2015. Substantially all of our long-lived assets were held in the United States as of December 31, 2017 and December 31, 2016.

Retirement Plans	12 Months Ended
Retirement Plans	Dec. 31, 2017
Retirement Benefits [Abstract]
Retirement Plans	Retirement Plans We have a defined contribution 401(k) retirement and savings plan (the “401(k) Plan”) to provide retirement benefits for all eligible employees. All employees who have completed forty-five days of service and are at least twenty-one years of age are eligible to participate in the 401(k) Plan. The 401(k) Plan allows eligible employees to make salary-deferred contributions up to 75% of their annual compensation, as defined, and subject to certain Internal Revenue Service limitations. Employer contributions vest at 25% per year, over four years. For the years ending December 31, 2017, 2016 and 2015, we incurred $3.3 million, $2.6 million and $1.9 million, respectively, in contribution expense related to the employer matching contributions. We are obligated to make plan contributions for the employees of certain of our wholly-owned foreign subsidiaries. For the years ending December 31, 2017, 2016 and 2015, we incurred $0.9 million, $0.7 million and $0.5 million, respectively, in contribution expense related to our foreign subsidiaries.

Selected Quarterly Information (Unaudited)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Information (Unaudited)

The following table sets forth unaudited quarterly consolidated statements of operations data for each of the eight quarters in 2017 and 2016. The information for each of these quarters has been prepared on the same basis as the audited annual consolidated financial statements included in this Annual Report on Form 10-K. In our opinion, the quarterly financial data reflects all adjustments, which consist only of normal recurring adjustments that we consider necessary for a fair presentation of this data. The quarterly financial data should be read in conjunction with our consolidated financial statements and related notes included elsewhere in this Annual Report on Form 10-K. These quarterly results are not necessarily indicative of our operating results to be expected in the future.



	Three Months Ended
	Dec 31, 2017			Sep 30, 2017			Jun 30, 2017			Mar 31, 2017			Dec 31, 2016			Sep 30, 2016			Jun 30, 2016			Mar 31, 2016
	(in thousands)
	(unaudited)
Consolidated Statement of
Operations Data:
Revenue:
Subscriptions, software and support	$	25,398		$	22,660		$	22,012		$	21,444		$	19,365		$	17,668		$	17,321		$	15,618
Professional services	25,164			21,988			21,186			16,885			14,382			13,077			15,146			20,346
Total revenue	50,562			44,648			43,198			38,329			33,747			30,745			32,467			35,964
Cost of revenue:
Subscriptions, software and support	2,488			2,341			2,488			2,062			1,929			1,890			1,836			1,782
Professional services	16,169			14,272			14,149			10,628			8,670			9,315			11,723			12,978
Total cost of revenue	18,657			16,613			16,637			12,690			10,599			11,205			13,559			14,760
Gross profit	31,905			28,035			26,561			25,639			23,148			19,540			18,908			21,204
Operating expenses:
Sales and marketing	22,463			19,725			22,775			17,003			14,660			14,480			13,831			11,166
Research and development	8,968			8,596			9,971			7,300			6,069			6,702			5,296			4,927
General and administrative	7,429			6,237			8,635			4,849			4,260			4,531			4,318			3,930
Total operating expenses	38,860			34,558			41,381			29,152			24,989			25,713			23,445			20,023
Operating (loss) income	(6,955		)	(6,523		)	(14,820		)	(3,513		)	(1,841		)	(6,173		)	(4,537		)	1,181
Other (income) expense:
Other (income) expense, net	(380		)	(425		)	(734		)	(499		)	1,663			(67		)	733			(537		)
Interest expense (income)	22			(2		)	197			256			256			243			241			242
Total other (income) expense	(358		)	(427		)	(537		)	(243		)	1,919			176			974			(295		)
Net (loss) income before income taxes	(6,597		)	(6,096		)	(14,283		)	(3,270		)	(3,760		)	(6,349		)	(5,511		)	1,476
Income tax expense (benefit)	272			188			176			125			423			(1,610		)	(1,217		)	721
Net (loss) income⁽¹⁾	$	(6,869	)	$	(6,284	)	$	(14,459	)	$	(3,395	)	$	(4,183	)	$	(4,739	)	$	(4,294	)	$	755

(1) In the second quarter of 2017, we recorded $6.2 million of cumulative stock-based compensation expense upon the

effectiveness of our IPO and $2.4 million of stock-based compensation expense related to the stock option modifications.

See Note 7 for further discussion of stock-based compensation expense.

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Basis of Presentation

Use of Estimates

Principles of Consolidation

The accompanying consolidated financial statements include the accounts of Appian and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.

Initial Public Offering

Revenue Recognition

Subscriptions, Software and Support Revenue

SaaS Subscriptions

Term License Subscriptions

Professional Services

Multiple Element Arrangements

SaaS Subscriptions

Term License Subscriptions

Deferred Revenue

Cost of Revenue

Cost of Subscriptions, Software and Support Revenue

Cost of Professional Services Revenue

Concentration of Credit Risk

Cash and Cash Equivalents

We consider all highly liquid investments with an original or remaining maturity of three months or less at the date of purchase, as well as overnight repurchase investments, to be cash equivalents.

Accounts Receivable and Allowance for Doubtful Accounts

Deferred Commissions

Property, Plant and Equipment

Property and Equipment



Asset Category		Useful Life (in years)
Computer software		3
Computer hardware		3
Equipment		5
Office furniture and fixtures		10
Leasehold improvements		Shorter of useful life of assets or lease term

Impairment of Long-Lived Assets

Fair Value of Financial Instruments


•	Level 1. Observable inputs based on unadjusted quoted prices in active markets for identical assets or liabilities;


•	Level 2. Inputs, other than quoted prices in active markets, that are observable either directly or indirectly; and


•	Level 3. Unobservable inputs for which there is little or no market data, which require us to develop our own assumptions.

Assets and Liabilities Measured at Fair Value on a Recurring Basis

Stock-Based Compensation

Basic and Diluted Loss per Common Share

Income Taxes

Segment Reporting

Foreign Currency

Research and Development

Advertising

We expense advertising costs as they are incurred. Advertising expenses were $3.0 million, $1.4 million and $0.5 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Emerging Growth Company Status

Recent Accounting Pronouncements

Adopted

Not Yet Adopted

Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Property, Plant and Equipment, Useful Life



Asset Category		Useful Life (in years)
Computer software		3
Computer hardware		3
Equipment		5
Office furniture and fixtures		10
Leasehold improvements		Shorter of useful life of assets or lease term

Property and equipment consisted of the following as of December 31 (in thousands):



	2017			2016
Computer software	$	1,727		$	1,701
Computer hardware	1,644			1,408
Leasehold improvements	4,226			4,098
Office furniture and fixtures	510			464
Equipment	131			116
	8,238			7,787
Less: accumulated depreciation	(5,575		)	(4,686		)
Property and equipment, net	$	2,663		$	3,101

Summary of Liabilities Fair Value Measurements

The following table summarizes the conclusions reached as of December 31, 2016 (in thousands):



	December 31, 2016		Level 1		Level 2		Level 3
Liabilities:
Series A convertible preferred stock warrant(1)	$	850	$	—	$	—	$	850
	$	850	$	—	$	—	$	850

(1)

Summary of Changes in Level 3 Instruments Measured at Fair Value On Recurring Basis

The following table presents the changes in our Level 3 instruments measured at fair value on a recurring basis during the years ended December 31, 2017, 2016 and 2015 (in thousands):



	Year Ended December 31,
	2017			2016		2015
Balance as of January 1,	$	850		$	650	$	351
Change in fair value of warrant liability	341			200		299
Reclassification of warrant liability to equity	(1,191		)	—		—
Balance as of December 31,	$	—		$	850	$	650

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Summary of Property and Equipment



Asset Category		Useful Life (in years)
Computer software		3
Computer hardware		3
Equipment		5
Office furniture and fixtures		10
Leasehold improvements		Shorter of useful life of assets or lease term

Property and equipment consisted of the following as of December 31 (in thousands):



	2017			2016
Computer software	$	1,727		$	1,701
Computer hardware	1,644			1,408
Leasehold improvements	4,226			4,098
Office furniture and fixtures	510			464
Equipment	131			116
	8,238			7,787
Less: accumulated depreciation	(5,575		)	(4,686		)
Property and equipment, net	$	2,663		$	3,101

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Schedule of Income before Income Tax

For the years ended December 31, 2017, 2016 and 2015, our net loss before income taxes was comprised of the following (in thousands):



	2017			2016			2015
Domestic	$	(23,093	)	$	(4,524	)	$	1,079
Foreign	(7,153		)	(9,620		)	(7,688		)
Total	$	(30,246	)	$	(14,144	)	$	(6,609	)

Schedule of Components of Income Tax Expense (Benefit)

For the years ended December 31, 2017, 2016 and 2015, our income tax expense (benefit) was comprised of the following (in thousands):



	2017			2016			2015
Current:
Federal	$	(65	)	$	(627	)	$	390
State	68			(200		)	62
Foreign	1,009			266			217
Total current expense (benefit)	1,012			(561		)	669
Deferred:
Federal	(42		)	(922		)	(334		)
State	—			(230		)	43
Foreign	(209		)	30			—
Total deferred expense (benefit)	(251		)	(1,122		)	(291		)
Total income tax expense (benefit)	$	761		$	(1,683	)	$	378

Schedule of Effective Income Tax Rate Reconciliation



	2017		2016		2015
U.S. federal statutory tax rate	34.0	%	34.0	%	34.0	%
State tax expense	4.9		1.4		(0.9	)
Foreign rate differential	(6.7	)	(17.8	)	(29.4	)
Nondeductible expenses	(0.9	)	(2.3	)	(4.1	)
Tax credits	5.8		6.5		10.0
Unrecognized tax benefits	(0.7	)	(0.2	)	(1.8	)
Other	(0.3	)	(0.2	)	(1.9	)
Remeasurement of deferred taxes	(7.0	)	—		—
Change in valuation allowance	(31.6	)	(9.6	)	(11.5	)
Total	(2.5	)%	11.8	%	(5.6	)%

Schedule of Deferred Tax Assets and Liabilities

As of December 31, 2017 and 2016, significant components of our deferred tax assets and liabilities were as follows (in thousands):



	2017			2016
Deferred tax assets:
Accrued vacation	$	967		$	529
Bad debt	109			159
Deferred revenue	1,248			2,176
Deferred rent	473			834
Tax credits	4,169			2,401
Net operating losses	10,413			2,939
Equity compensation	1,207			—
Other	287			929
Gross deferred tax assets	18,873			9,967
Less: Valuation allowance	(12,328		)	(2,642		)
Total deferred tax assets	6,545			7,325
Deferred tax liabilities:
Depreciation	(174		)	(349		)
Unbilled receivables	(555		)	(491		)
Prepaid expenses	(5,614		)	(6,505		)
Other	(8		)	—
Total deferred tax liabilities	(6,351		)	(7,345		)
Net deferred tax asset (liability)	$	194		$	(20	)

Summary of Income Tax Contingencies

The following table summarizes the activity related to our unrecognized tax benefit from December 31, 2014 to December 31, 2017 (in thousands):



Balance as of December 31, 2014	$	286
Additions for tax positions in current years	98
Additions for tax positions in prior years	—
Reductions due to lapse in statutes of limitations	—
Settlements	—
Balance as of December 31, 2015	384
Additions for tax positions in current years	171
Additions for tax positions in prior years	—
Reductions due to lapse in statutes of limitations	(136		)
Settlements	—
Balance as of December 31, 2016	419
Additions for tax positions in current years	232
Additions for tax positions in prior years	—
Reductions due to lapse in statutes of limitations	—
Settlements	—
Balance as of December 31, 2017	$	651

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

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

Summary of Assumptions Used to Estimate the Fair Value of Stock Options Granted

The following table summarizes the assumptions used to estimate the fair value of stock options granted during the years ended December 31:



	2017	2016	2015
Risk-free interest rate	1.9% - 2.2%	1.3% - 1.5%	1.7% - 1.9%
Expected term (in years)	6.5	6.5	6.5
Expected volatility	38.1% - 40.6%	40.9% - 42.0%	39.7% - 44.4%
Expected dividend yield	—%	—%	—%

Summary of the Stock Option Activity

The following table summarizes the stock option activity for the year ended December 31, 2017:



	Number of Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value (in thousands)
Outstanding at January 1, 2017	6,784,448		$	4.65	6.5	$	44,259
Granted	1,256,200		11.92
Exercised	(876,121	)	1.27			14,807
Canceled	(153,640	)	7.29
Outstanding at December 31, 2017	7,010,887		6.36		6.6	176,122
Exercisable at December 31, 2017	2,800,447		2.07		3.9	82,367

Schedule of Restricted Stock Unit Activity

The following table summarizes the restricted stock unit activity for the year ended December 31, 2017:



	Number of Shares		Weighted Average Grant Date Fair Value
Non-vested outstanding at January 1, 2017	—		$	—
Granted	738,055		22.15
Vested	(4,930	)	20.24
Canceled	(1,150	)	21.40
Non-vested outstanding at December 31, 2017	731,975		22.16

Schedule of Components of Stock-based Compensation Expense

The following table summarizes the components of our stock-based compensation expense for the year ended December 31, 2017 (in thousands):



	2017
Stock-based compensation expense related to stock option modifications	$	2,394
Cumulative stock-based compensation expense related to stock options recorded upon effectiveness of our IPO	6,236
Post-IPO stock-based compensation expense related to stock options	3,371
Stock-based compensation expense related to the issuance of common stock to directors	222
Stock-based compensation expense related to restricted stock units	753
Total stock-based compensation expense	$	12,976

Schedule of Stock-based Compensation Expense Included in Condensed Consolidated Statements of Operations



	2017
Cost of revenue
Subscriptions, software and support	$	575
Professional services	1,295
Operating expenses
Sales and marketing	3,233
Research and development	2,822
General and administrative	5,051
Total stock-based compensation expense	$	12,976

Convertible Preferred Stock and Stockholders’ Equity (Deficit) (Tables)

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Summary of Activity for Convertible Preferred Stock Issued and Outstanding

The following tables present a summary of activity for our convertible preferred stock issued and outstanding for the years ended December 31, 2017, 2016 and 2015 (dollar amounts in thousands):



	Series A Convertible Preferred Stock					Series B Convertible Preferred Stock
	Amount			Shares		Amount			Shares
Balance as of January 1, 2015	$	16,197		12,043,108		$	37,500		6,120,050
Accretion of dividends on convertible preferred stock	861			—		—			—
Balance as of December 31, 2015	$	17,058		12,043,108		$	37,500		6,120,050
Accretion of dividends on convertible preferred stock	857			—		—			—
Balance as of December 31, 2016	$	17,915		12,043,108		$	37,500		6,120,050
Accretion of dividends on convertible preferred stock	357			—		—			—
Payment of accrued dividend to Series A convertible preferred stockholders	(7,565		)	—		—			—
Conversion of convertible preferred stock to common stock	(10,707		)	(12,043,108	)	(37,500		)	(6,120,050	)
Balance as of December 31, 2017	$	—		—		$	—		—

Basic and Diluted Loss per Common Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted

The following table sets forth the computation of basic and diluted net loss per share for the years ended December 31 (in thousands, except per share data):



	Year Ended December 31,
	2017			2016			2015
Numerator:
Net loss	$	(31,007	)	$	(12,461	)	$	(6,987	)
Accretion of dividends on convertible preferred stock	357			857			861
Net loss attributable to common stockholders	$	(31,364	)	$	(13,318	)	$	(7,848	)
Denominator
Weighted average common shares outstanding, basic and diluted	49,529,833			34,274,718			34,274,718
Net loss per share attributable to common stockholders, basic and diluted	$	(0.63	)	$	(0.39	)	$	(0.23	)

Summary of Securities Excluded From Calculation of Weighted Average Common Shares



	Year Ended December 31,
	2017	2016	2015
Convertible preferred stock:
Series A convertible preferred stock	—	12,043,108	12,043,108
Series B convertible preferred stock	—	6,120,050	6,120,050
Warrant to purchase Series A convertible preferred stock	—	84,360	84,360
Stock options	7,010,887	6,784,448	4,589,988
Restricted stock units	731,975	—	—

Selected Quarterly Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information

These quarterly results are not necessarily indicative of our operating results to be expected in the future.



	Three Months Ended
	Dec 31, 2017			Sep 30, 2017			Jun 30, 2017			Mar 31, 2017			Dec 31, 2016			Sep 30, 2016			Jun 30, 2016			Mar 31, 2016
	(in thousands)
	(unaudited)
Consolidated Statement of
Operations Data:
Revenue:
Subscriptions, software and support	$	25,398		$	22,660		$	22,012		$	21,444		$	19,365		$	17,668		$	17,321		$	15,618
Professional services	25,164			21,988			21,186			16,885			14,382			13,077			15,146			20,346
Total revenue	50,562			44,648			43,198			38,329			33,747			30,745			32,467			35,964
Cost of revenue:
Subscriptions, software and support	2,488			2,341			2,488			2,062			1,929			1,890			1,836			1,782
Professional services	16,169			14,272			14,149			10,628			8,670			9,315			11,723			12,978
Total cost of revenue	18,657			16,613			16,637			12,690			10,599			11,205			13,559			14,760
Gross profit	31,905			28,035			26,561			25,639			23,148			19,540			18,908			21,204
Operating expenses:
Sales and marketing	22,463			19,725			22,775			17,003			14,660			14,480			13,831			11,166
Research and development	8,968			8,596			9,971			7,300			6,069			6,702			5,296			4,927
General and administrative	7,429			6,237			8,635			4,849			4,260			4,531			4,318			3,930
Total operating expenses	38,860			34,558			41,381			29,152			24,989			25,713			23,445			20,023
Operating (loss) income	(6,955		)	(6,523		)	(14,820		)	(3,513		)	(1,841		)	(6,173		)	(4,537		)	1,181
Other (income) expense:
Other (income) expense, net	(380		)	(425		)	(734		)	(499		)	1,663			(67		)	733			(537		)
Interest expense (income)	22			(2		)	197			256			256			243			241			242
Total other (income) expense	(358		)	(427		)	(537		)	(243		)	1,919			176			974			(295		)
Net (loss) income before income taxes	(6,597		)	(6,096		)	(14,283		)	(3,270		)	(3,760		)	(6,349		)	(5,511		)	1,476
Income tax expense (benefit)	272			188			176			125			423			(1,610		)	(1,217		)	721
Net (loss) income⁽¹⁾	$	(6,869	)	$	(6,284	)	$	(14,459	)	$	(3,395	)	$	(4,183	)	$	(4,739	)	$	(4,294	)	$	755

(1) In the second quarter of 2017, we recorded $6.2 million of cumulative stock-based compensation expense upon the

effectiveness of our IPO and $2.4 million of stock-based compensation expense related to the stock option modifications.

See Note 7 for further discussion of stock-based compensation expense.

Significant Accounting Policies - Additional Information (Details)	1 Months Ended		12 Months Ended
	Nov. 30, 2017 $ / shares shares	May 31, 2017 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) agency	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Net proceeds from initial public offering			$ 80,213,000	$ 0	$ 0
Deferred offering costs			$ 2,400,000
Percentage of license revenue			1.00%	1.00%	1.90%
Change in allowance for doubtful accounts			$ 0	$ 0
Commission expense			11,800,000	6,500,000	$ 4,600,000
Foreign currency transactions, gains and (losses)			2,600,000	(1,500,000)	(1,300,000)
Advertising expense			$ 3,000,000	$ 1,400,000	$ 500,000
Customer Concentration Risk \| Sales Revenue, Net \| Foreign Customers
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage			27.00%	19.50%	19.90%
Customer Concentration Risk \| Sales Revenue, Net \| Government Agencies
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage			15.40%	26.20%	32.70%
Customer Concentration Risk \| Sales Revenue, Net \| Federal Government Agencies
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage			8.40%	17.70%	20.80%
Number of federal government agencies \| agency			3
Customer Concentration Risk \| Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage			7.00%	17.20%
Minimum
Summary Of Significant Accounting Policies [Line Items]
SaaS Subscriptions contracts term			1 year
Term license subscription contracts term			1 year
Maximum
Summary Of Significant Accounting Policies [Line Items]
SaaS Subscriptions contracts term			5 years
Term license subscription contracts term			5 years
Class A Common Stock
Summary Of Significant Accounting Policies [Line Items]
Net proceeds from initial public offering		$ 77,800,000
IPO \| Class A Common Stock
Summary Of Significant Accounting Policies [Line Items]
Sale of Stock, Number of Shares Issued in Transaction \| shares		7,187,500
Sale of Stock, Price Per Share \| $ / shares		$ 12.00
Secondary Offering \| Class A Common Stock
Summary Of Significant Accounting Policies [Line Items]
Sale of Stock, Number of Shares Issued in Transaction \| shares	4,370,000
Sale of Stock, Price Per Share \| $ / shares	$ 20.25
Computer software
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life			3 years
Computer hardware
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life			3 years
Equipment
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life			5 years
Office furniture and fixtures
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life			10 years

Significant Accounting Policies - Summary of Liabilities Fair Value Measurements (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, Liabilities		$ 850
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, Liabilities	$ 0	850	$ 650	$ 351
Series A Convertible Preferred Stock Warrant
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, Liabilities		850
Series A Convertible Preferred Stock Warrant \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurements, Liabilities		$ 850

Significant Accounting Policies - Summary of Changes in Level 3 Instruments Measured at Fair Value On Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance as of January 1,	$ 850
Balance as of December 31		$ 850
Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance as of January 1,	850	650	$ 351
Change in fair value of warrant liability	341	200	299
Reclassification of warrant liability to equity	(1,191)	0	0
Balance as of December 31	$ 0	$ 850	$ 650

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 8,238	$ 7,787
Less: accumulated depreciation	(5,575)	(4,686)
Property and equipment, net	2,663	3,101
Depreciation and amortization expense	900	800	$ 800
Computer software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,727	1,701
Computer hardware
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,644	1,408
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	4,226	4,098
Office furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	510	464
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 131	$ 116

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Accrued contract labor costs	$ 3,424	$ 743
Accrued hosting costs	466	0
Accrued audit and tax expenses	248	358
Accrued reimbursable employee expenses	286	134
Accrued marketing and tradeshow expenses	128	111
Other accrued expenses	1,915	1,514
Total	$ 6,467	$ 2,860

Debt - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
Debt - Additional Information (Detail) - USD ($)	Nov. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Apr. 30, 2017	Jan. 31, 2016	Mar. 31, 2015
Line of Credit Facility [Line Items]
Loss on extinguishment of debt		$ (384,000)	$ 0	$ 0
Revolving Credit Facility
Line of Credit Facility [Line Items]
Credit facility	$ 20,000,000			$ 10,000,000	$ 5,000,000
Term Loan
Line of Credit Facility [Line Items]
Credit facility					20,000,000	$ 20,000,000	$ 10,000,000
Line of credit, outstanding borrowings		0
Term Loan \| Other (Income) Expense
Line of Credit Facility [Line Items]
Loss on extinguishment of debt		$ (400,000)
Subordinated Term Loan
Line of Credit Facility [Line Items]
Credit facility					$ 10,000,000
Minimum
Line of Credit Facility [Line Items]
Unused facility fee, revolving line of credit	0.15%
Adjusted quick ratio	135.00%
Minimum \| London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Additional interest rate margin	2.00%
Minimum \| Prime Rate
Line of Credit Facility [Line Items]
Additional interest rate margin	1.00%
Maximum
Line of Credit Facility [Line Items]
Unused facility fee, revolving line of credit	0.25%
Maximum \| London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Additional interest rate margin	2.50%
Maximum \| Prime Rate
Line of Credit Facility [Line Items]
Additional interest rate margin	1.50%

Income Taxes - Net Income (Loss) Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic									$ (23,093)	$ (4,524)	$ 1,079
Foreign									(7,153)	(9,620)	(7,688)
Total	$ (6,597)	$ (6,096)	$ (14,283)	$ (3,270)	$ (3,760)	$ (6,349)	$ (5,511)	$ 1,476	$ (30,246)	$ (14,144)	$ (6,609)

Income Taxes - Schedule of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal									$ (65)	$ (627)	$ 390
State									68	(200)	62
Foreign									1,009	266	217
Total current expense (benefit)									1,012	(561)	669
Deferred:
Federal									(42)	(922)	(334)
State									0	(230)	43
Foreign									(209)	30	0
Total deferred expense (benefit)									(251)	(1,122)	(291)
Total income tax expense (benefit)	$ 272	$ 188	$ 176	$ 125	$ 423	$ (1,610)	$ (1,217)	$ 721	$ 761	$ (1,683)	$ 378

Income Taxes - Schedule of Reconciliation of Statutory to Effective Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
U.S. federal statutory tax rate	34.00%	34.00%	34.00%
State tax expense	4.90%	1.40%	(0.90%)
Foreign rate differential	(6.70%)	(17.80%)	(29.40%)
Nondeductible expenses	(0.90%)	(2.30%)	(4.10%)
Tax credits	5.80%	6.50%	10.00%
Unrecognized tax benefits	(0.70%)	(0.20%)	(1.80%)
Other	(0.30%)	(0.20%)	(1.90%)
Remeasurement of deferred taxes	(7.00%)	(0.00%)	(0.00%)
Change in valuation allowance	(31.60%)	(9.60%)	(11.50%)
Total	(2.50%)	11.80%	(5.60%)

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Accrued vacation	$ 967	$ 529
Bad debt	109	159
Deferred revenue	1,248	2,176
Deferred rent	473	834
Tax credits	4,169	2,401
Net operating losses	10,413	2,939
Equity compensation	1,207	0
Other	287	929
Gross deferred tax assets	18,873	9,967
Less: Valuation allowance	(12,328)	(2,642)
Total deferred tax assets	6,545	7,325
Deferred tax liabilities:
Depreciation	(174)	(349)
Unbilled receivables	(555)	(491)
Prepaid expenses	(5,614)	(6,505)
Other	(8)	0
Total deferred tax liabilities	(6,351)	(7,345)
Net deferred tax liability	$ 194
Net deferred tax asset (liability)		$ (20)

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Beginning balance	$ 419	$ 384	$ 286
Additions for tax positions in current years	232	171	98
Additions for tax positions in prior years	0	0	0
Reductions due to lapse in statutes of limitations	0	(136)	0
Settlements	0	0	0
Ending balance	$ 651	$ 419	$ 384

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Income tax expense, related to the Tax Cuts and Jobs Act	$ 2,100
Operating loss carryforwards, state, tax effected	1,600	$ 100
Net change in total valuation allowance	9,700
Valuation allowance against foreign deferred tax assets	12,328	2,642
Unrecognized tax benefits, portion affecting tax rate	500	400
Recognized interest and penalties related to uncertain tax positions	2	2	$ 19
Cumulative balance of interest and penalties related to uncertain tax positions	33	35
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	25,300	1,800
Federal tax credit carryforwards	4,500	2,800
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	25,300	1,700
Swiss Federal Tax Administration (FTA) \| Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	35,700	$ 23,700
Valuation allowance against foreign deferred tax assets	$ 3,500

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended	12 Months Ended
	Apr. 25, 2017	May 31, 2017	Jun. 30, 2017	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period for option exercise				5 years
Stock-based compensation expense				$ 12,976
Cumulative stock-based compensation expense related to stock options recorded upon effectiveness of our IPO
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense				6,236
Cumulative stock-based compensation expense related to stock options recorded upon effectiveness of our IPO \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 6,200	$ 6,200
Stock Option Modifications
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 2,400		$ 2,400	$ 2,394
2017 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available to be issued				5,775,770
2017 Equity Incentive Plan \| Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available to be issued		6,421,442		6,538,262
2007 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available to be issued		421,442
Number of shares available for grants		0
Period for which options can be granted				10 years

Stock-Based Compensation - Summary of Estimate the Fair Value of Stock Options Granted (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Goods and Nonemployee Services Transaction [Line Items]
Expected term (in years)	6 years 6 months	6 years 6 months	6 years 6 months
Expected dividend yield	0.00%	0.00%	0.00%
Minimum
Share-based Goods and Nonemployee Services Transaction [Line Items]
Risk-free interest rate	1.90%	1.30%	1.70%
Expected volatility	38.10%	40.90%	39.70%
Maximum
Share-based Goods and Nonemployee Services Transaction [Line Items]
Risk-free interest rate	2.20%	1.50%	1.90%
Expected volatility	40.60%	42.00%	44.40%

Stock-Based Compensation - Summary of the Stock Option Activity (Detail) - USD ($)		3 Months Ended	12 Months Ended
	Apr. 25, 2017	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Number of Shares
Outstanding at January 1, 2017			6,784,448
Granted			1,256,200
Exercised			(876,121)
Canceled			(153,640)
Outstanding at December 31, 2017			7,010,887	6,784,448
Exercisable at December 31, 2017			2,800,447
Weighted Average Exercise Price
Outstanding at January 1, 2017			$ 4.65
Granted			11.92
Exercised			1.27
Canceled			7.29
Outstanding at December 31, 2017			6.36	$ 4.65
Exercisable at December 31, 2017			$ 2.07
Weighted Average Remaining Contractual Term (Years)
Outstanding at January 1, 2017			6 years 7 months	6 years 6 months
Outstanding at December 31, 2017			6 years 7 months	6 years 6 months
Exercisable at December 31, 2017			3 years 11 months
Aggregate Intrinsic Value (in thousands)
Outstanding at January 1, 2017			$ 44,259,000
Exercised			14,807,000
Outstanding at December 31, 2017			176,122,000	$ 44,259,000
Exercisable at December 31, 2017			$ 82,367,000
Weighted average grant-date fair value of options granted (in usd per share)			$ 5.05	$ 4.35
Total fair value of stock options vested			$ 5,600,000	$ 0
Total compensation cost related to unvested stock options not yet recognized			$ 11,000,000
Weighted average period, unvested stock options			2 years 9 months 18 days
Stock options issued to purchase common stock (in shares)	216,160
Stock-based compensation expense			$ 12,976,000
Stock Option Modifications
Aggregate Intrinsic Value (in thousands)
Stock-based compensation expense	$ 2,400,000	$ 2,400,000	$ 2,394,000

Stock-Based Compensation - Schedule of Restricted Stock Unit Activity (Details) - Restricted Stock Units $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Number of Shares
Non-vested outstanding at December 31, 2016 (in shares) \| shares	0
Granted (in shares) \| shares	738,055
Vesting of restricted stock units (in shares) \| shares	(4,930)
Canceled (in shares) \| shares	(1,150)
Non-vested outstanding at December 31, 2017 (in shares) \| shares	731,975
Weighted Average Grant Date Fair Value
Non-vested outstanding at December 31, 2016 (in usd per share) \| $ / shares	$ 0.00
Granted (in usd per share) \| $ / shares	22.15
Vested (in usd per share) \| $ / shares	20.24
Canceled (in usd per share) \| $ / shares	21.40
Non-vested outstanding at December 31, 2017 (in usd per share) \| $ / shares	$ 22.16
Total unrecognized compensation cost related to unvested restricted stock units \| $	$ 15.6
Weighted average remaining vesting period	2 years 9 months 18 days

Stock-Based Compensation - Schedule of Stock-based Compensation Expense (Detail) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	Apr. 25, 2017	Jun. 30, 2017	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense			$ 12,976
Stock-based compensation expense related to stock option modifications
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 2,400	$ 2,400	2,394
Cumulative stock-based compensation expense related to stock options recorded upon effectiveness of our IPO
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense			6,236
Post-IPO stock-based compensation expense related to stock options
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense			3,371
Stock-based compensation expense related to the issuance of common stock to directors
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense			222
Stock-based compensation expense related to restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense			$ 753

Stock-Based Compensation - Schedule of Stock-based Compensation Expense Included in Condensed Consolidated Statements of Operations (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 12,976
Subscriptions, software and support
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	575
Professional services
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	1,295
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	3,233
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	2,822
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 5,051

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017 vote shares
Temporary Equity [Line Items]
Convertible preferred stock outstanding shares converted into common stock (in shares)	1
Class B Common Stock
Temporary Equity [Line Items]
Conversion of convertible preferred stock to common stock (in shares)	18,163,158
Preferred stock conversion basis	1
Convertible preferred stock outstanding shares converted into common stock (in shares)	1
Number of votes entitled to stockholders \| vote	10
Class A Common Stock
Temporary Equity [Line Items]
Number of votes entitled to stockholders \| vote	1
Conversion of stock (in shares)	1
Maximum percentage of aggregate voting power of capital stock which triggers conversion of stock	10.00%

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Summary of Activity for Convertible Preferred Stock Issued and Outstanding (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Increase (Decrease) in Temporary Equity [Roll Forward]
Payment of accrued dividend to Series A convertible preferred stockholders	$ (7,565)	$ 0	$ 0
Series A Convertible Preferred Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance	$ 17,915	$ 17,058	$ 16,197
Beginning balance (in shares)	12,043,108	12,043,108	12,043,108
Accretion of dividends on convertible preferred stock	$ 357	$ 857	$ 861
Payment of accrued dividend to Series A convertible preferred stockholders	$ (7,565)
Conversion of convertible preferred stock to common stock (in shares)	(12,043,108)
Conversion of convertible preferred stock to common stock	$ (10,707)
Ending balance	$ 0	$ 17,915	$ 17,058
Ending balance (in shares)	0	12,043,108	12,043,108
Series B Convertible Preferred Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance	$ 37,500	$ 37,500	$ 37,500
Beginning balance (in shares)	6,120,050	6,120,050	6,120,050
Accretion of dividends on convertible preferred stock	$ 0	$ 0	$ 0
Payment of accrued dividend to Series A convertible preferred stockholders	$ 0
Conversion of convertible preferred stock to common stock (in shares)	(6,120,050)
Conversion of convertible preferred stock to common stock	$ (37,500)
Ending balance	$ 0	$ 37,500	$ 37,500
Ending balance (in shares)	0	6,120,050	6,120,050

Warrants - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2017	May 31, 2017
Class of Warrant or Right [Line Items]
Warrant exercise price (in dollars per share)	$ 0.88905
Warrant
Class of Warrant or Right [Line Items]
Fair value of warrant	$ 1.2
Series A Convertible Preferred Stock
Class of Warrant or Right [Line Items]
Warrant to purchase shares of preferred stock (in shares)	84,360
Class B Common Stock
Class of Warrant or Right [Line Items]
Shares issued on cashless exercise of warrants (in shares)		79,363
Class B Common Stock \| Prior to IPO
Class of Warrant or Right [Line Items]
Warrant to purchase shares of preferred stock (in shares)	84,360

Basic and Diluted Loss per Common Share - Computation of Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Numerator:
Net loss	$ (6,869)	$ (6,284)	$ (14,459)	$ (3,395)	$ (4,183)	$ (4,739)	$ (4,294)	$ 755	$ (31,007)	$ (12,461)	$ (6,987)
Accretion of dividends on convertible preferred stock									357	857	861
Net loss attributable to common stockholders									$ (31,364)	$ (13,318)	$ (7,848)
Denominator
Weighted average common shares outstanding, basic and diluted (in shares)									49,529,833	34,274,718	34,274,718
Net loss per share attributable to common stockholders, basic and diluted (in usd per share)									$ (0.63)	$ (0.39)	$ (0.23)

Basic and Diluted Loss per Common Share - Summary of Securities Excluded From Calculation of Weighted Average Common Shares Outstanding (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Series A Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Convertible preferred stock (in shares)	0	12,043,108	12,043,108
Series B Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Convertible preferred stock (in shares)	0	6,120,050	6,120,050
Warrant To Purchase Series A Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Convertible preferred stock (in shares)	0	84,360	84,360
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Convertible preferred stock (in shares)	7,010,887	6,784,448	4,589,988
Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Convertible preferred stock (in shares)	731,975	0	0

Commitments and Contingencies - Summary of Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Office Leases
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2018	$ 7,722
2019	8,043
2020	4,828
2021	2,503
2022	380
Thereafter	1,046
Future minimum lease commitments, net	24,522
Equipment Leases
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2018	405
2019	216
2020	22
2021	0
2022	0
Thereafter	0
Future minimum lease commitments, net	$ 643

Commitments and Contingencies -Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Deferred rent, noncurrent	$ 2.0	$ 2.4
Rental income from subtenant	0.5	0.6	$ 0.6
Total rent and lease expense	7.0	6.6	$ 4.6
Payment of royalty fees	0.3
Outstanding letters of credit	$ 1.1	$ 1.3

Segment and Geographic Information - Summary of Revenues By Geography (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 50,562	$ 44,648	$ 43,198	$ 38,329	$ 33,747	$ 30,745	$ 32,467	$ 35,964	$ 176,737	$ 132,923	$ 111,204
Domestic
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									128,997	107,069	89,043
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									$ 47,740	$ 25,854	$ 22,161

Retirement Plans (Details) - USD ($) $ in Millions	12 Months Ended
Retirement Plans (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Eligibility to participate, days of service	45 days
Eligibility to participate, years of age	21 years
Maximum annual contributions per employee	75.00%
Vesting percentage of employer contribution	25.00%
Vesting term of employer contribution	4 years
Contribution expense related to employer matching contributions	$ 3.3	$ 2.6	$ 1.9
Foreign Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contribution expense related to employer matching contributions	$ 0.9	$ 0.7	$ 0.5

Selected Quarterly Information (Unaudited) (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended								12 Months Ended
	Apr. 25, 2017	May 31, 2017	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense											$ 12,976
Revenue:
Subscriptions, software and support			$ 25,398	$ 22,660	$ 22,012	$ 21,444	$ 19,365	$ 17,668	$ 17,321	$ 15,618	91,514	$ 69,972	$ 53,207
Professional services			25,164	21,988	21,186	16,885	14,382	13,077	15,146	20,346	85,223	62,951	57,997
Total revenue			50,562	44,648	43,198	38,329	33,747	30,745	32,467	35,964	176,737	132,923	111,204
Cost of revenue:
Subscriptions, software and support			2,488	2,341	2,488	2,062	1,929	1,890	1,836	1,782	9,379	7,437	6,079
Professional services			16,169	14,272	14,149	10,628	8,670	9,315	11,723	12,978	55,218	42,686	42,402
Total cost of revenue			18,657	16,613	16,637	12,690	10,599	11,205	13,559	14,760	64,597	50,123	48,481
Gross profit			31,905	28,035	26,561	25,639	23,148	19,540	18,908	21,204	112,140	82,800	62,723
Operating expenses:
Sales and marketing			22,463	19,725	22,775	17,003	14,660	14,480	13,831	11,166	81,966	54,137	38,300
Research and development			8,968	8,596	9,971	7,300	6,069	6,702	5,296	4,927	34,835	22,994	16,750
General and administrative			7,429	6,237	8,635	4,849	4,260	4,531	4,318	3,930	27,150	17,039	12,515
Total operating expenses			38,860	34,558	41,381	29,152	24,989	25,713	23,445	20,023	143,951	94,170	67,565
Operating (loss) income			(6,955)	(6,523)	(14,820)	(3,513)	(1,841)	(6,173)	(4,537)	1,181	(31,811)	(11,370)	(4,842)
Other expense (income):
Other expense (income), net			(380)	(425)	(734)	(499)	1,663	(67)	733	(537)	(2,038)	1,792	1,579
Interest expense			22	(2)	197	256	256	243	241	242	473	982	188
Total other expense (income)			(358)	(427)	(537)	(243)	1,919	176	974	(295)	(1,565)	2,774	1,767
Net (loss) income before income taxes			(6,597)	(6,096)	(14,283)	(3,270)	(3,760)	(6,349)	(5,511)	1,476	(30,246)	(14,144)	(6,609)
Income tax (benefit) expense			272	188	176	125	423	(1,610)	(1,217)	721	761	(1,683)	378
Net loss			$ (6,869)	$ (6,284)	(14,459)	$ (3,395)	$ (4,183)	$ (4,739)	$ (4,294)	$ 755	(31,007)	$ (12,461)	$ (6,987)
Cumulative stock-based compensation expense related to stock options recorded upon effectiveness of our IPO
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense											6,236
Cumulative stock-based compensation expense related to stock options recorded upon effectiveness of our IPO \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 6,200			6,200
Stock Option Modifications
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 2,400				$ 2,400						$ 2,394

Organization and Description of Business	12 Months Ended
Organization and Description of Business	Dec. 31, 2017
Accounting Policies [Abstract]
Organization and Description of Business	Organization and Description of Business Appian Corporation (together with its subsidiaries, “Appian,” the “Company,” “we” or “our”) provides a leading low-code software development platform that enables organizations to rapidly develop powerful and unique applications. The applications created on our platform help companies drive digital transformation and competitive differentiation. We were incorporated in the state of Delaware in August 1999. We are headquartered in Reston, Virginia and have offices in Canada, Switzerland, the United Kingdom, France, Germany, the Netherlands, Italy, and Australia.

Warrants	12 Months Ended
Warrants	Dec. 31, 2017
Warrants and Rights Note Disclosure [Abstract]
Warrants	Warrants We previously issued a warrant to purchase 84,360 shares of Series A convertible preferred stock in conjunction with a credit facility with a lender at an exercise price of $0.88905 per share. Immediately prior to the completion of the IPO, this warrant was converted into a warrant to purchase 84,360 shares of Class B common stock. The fair value at the time of the conversion was $1.2 million and was recorded as additional paid-in capital and a reduction of the preferred stock warrant liability. In May 2017, the warrant holder exercised the warrant and we issued 79,363 shares of Class B common stock through a cashless exercise of the warrant, in accordance with its terms.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events In preparing our consolidated financial statements, we evaluated subsequent events through February 23, 2018, which is the date that the consolidated financial statements were available to be issued.