Significant Accounting Policies | 2. Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed 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”) for interim financial information. In the opinion of management, the interim financial information includes all adjustments of a normal recurring nature necessary for a fair presentation of the results of operations, financial position, changes in stockholders’ equity (deficit) and cash flows. The results of operations for the current period are not necessarily indicative of the results for the full year or the results for any future periods. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related footnotes included in our final prospectus for our initial public offering (“IPO”) dated as of May 24, 2017 and filed with the Securities and Exchange Commission (the “SEC”) pursuant to Rule 424(b)(4) under the Securities Act of 1933, as amended. Use of Estimates The preparation of our condensed consolidated financial statements in conformity with U.S. GAAP requires us to make estimates and judgments that affect the amounts reported in these condensed 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 condensed 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 condensed 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 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 7 for further discussion of the convertible preferred stock and Note 8 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. 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 0.2% and 0.6% of our total revenue for the three and six months ended June 30, 2017, respectively. Revenue from our perpetual software licenses was 0.4% and 0.5% of our total revenue for the three and six months ended June 30, 2016, respectively. 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. Perpetual Licenses Our perpetual license revenue is derived from customers with perpetual licenses to our platform and associated maintenance and support contracts. We recognize revenue from perpetual licenses on the date of delivery to our customer. We sell maintenance and support to perpetual license customers separately from the perpetual licenses pursuant to agreements that generally renew annually. Maintenance and support revenue is deferred and recognized ratably over the term of the support period. 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, plus the cost of any materials delivered. 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, term license subscriptions, and perpetual licenses 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. Perpetual Licenses For multiple element arrangements involving our perpetual software licenses, we allocate revenue to the software license arrangement by determining if VSOE of fair value exists for the undelivered elements, which are usually maintenance and support and professional services. In situations where VSOE of fair value exists for the undelivered elements, we apply the residual method whereby the fees allocated to license revenue are recognized upon delivery, the fees allocated to maintenance and support revenue are recognized over the service period and the fees allocated to professional services and training are recognized as performed. In instances where we lack VSOE of fair value for the undelivered elements, revenue is either deferred until the final element is delivered or recognized ratably over the service period when the only undelivered elements are either professional services or maintenance and support. We have VSOE for maintenance and support elements and professional services elements performed on a time and materials basis. VSOE of fair value is based upon the price charged when the same element is sold separately. In determining VSOE of fair value, we require that a substantial majority of the selling prices fall within a reasonably narrow pricing range. We reassess VSOE annually or more frequently if required. 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 15.8% and 16.1% of our revenue for the three and six months ended June 30, 2017, respectively, of which the top three federal government agencies generated 9.2% and 9.9% of our revenue for the three and six months ended June 30, 2017, respectively. Additionally, 25.1% and 24.0% of our revenue during the three and six months ended June 30, 2017, respectively, was generated from foreign customers. Revenue generated from government agencies represented 28.2% and 32.6% of our revenue for the three and six months ended June 30, 2016, respectively, of which the top three federal government agencies generated 15.6% and 22.4% of our revenue for the three and six months ended June 30, 2016, respectively. Additionally, 19.1% and 16.6% of our revenue during the three and six months ended June 30, 2016, respectively, was generated from foreign customers. Federal government agencies accounted for 16.4% and 17.2% of accounts receivable at June 30, 2017 and December 31, 2016, respectively. 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 June 30, 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 condensed consolidated statements of operations. Commission expense was $2.7 million and $5.3 million for the three and six months ended June 30, 2017, respectively. Commission expense was $1.8 million and $3.6 million for the three and six months ended June 30, 2016, respectively. 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 June 30, 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 June 30, 2017. See Note 8 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 three months ended June 30, 2017 and 2016 (in thousands): Three Months Ended June 30, 2017 2016 Balance as of April 1 $ 850 $ 650 Change in fair value of warrant liability 341 200 Reclassification of warrant liability to equity (1,191 ) — Balance as of June 30 $ — $ 850 The following table presents the changes in our Level 3 instruments measured at fair value on a recurring basis during the six months ended June 30, 2017 and 2016 (in thousands): Six Months Ended June 30, 2017 2016 Balance as of January 1 $ 850 $ 650 Change in fair value of warrant liability 341 200 Reclassification of warrant liability to equity (1,191 ) — Balance as of June 30 $ — $ 850 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. As discussed in “—Recent Accounting Pronouncements,” we have elected to early adopt Accounting Standards Update (“ASU”) No. 2016-09, which, among other things, permits an entity to make an entity-wide policy election to either (1) estimate the number of awards that are expected to vest or (2) account for forfeitures when they occur. We have elected to account for forfeitures as they occur, rather than estimate expected forfeitures. 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 In August 2014, the FASB issued ASU No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern In April 2015, the FASB issued ASU No. 2015-03, Simplifying the Presentation of Debt Issuance Costs Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements In April 2015, the FASB issued ASU No. 2015-05, Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes (Topic 740) In March 2016, the FASB issued ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting (Topic 718) Not Yet Adopted In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) (“ASU 2014-09”), which provides new guidance for revenue recognition. ASU 2014-09 provides that an entity Principal Versus Agent Considerations (Reporting Revenue Gross Versus Net) Identifying Performance Obligations and Licensing Narrow-Scope Improvements and Practical Expedients 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 are in the initial stages of our evaluation of 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 impacts 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. 2016-02, Leases (Topic 842) In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments |