Five9 (FIVN) 10-Q 3 Aug 17 2017 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Jul. 27, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	Five9, Inc.
Trading Symbol	FIVN
Entity Central Index Key	1,288,847
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		55,116,559

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 57,149	$ 58,122
Accounts receivable, net	16,281	13,881
Prepaid expenses and other current assets	7,074	3,008
Total current assets	80,504	75,011
Property and equipment, net	15,656	14,688
Intangible assets, net	1,306	1,539
Goodwill	11,798	11,798
Other assets	2,199	2,203
Total assets	111,463	105,239
Current liabilities:
Accounts payable	4,586	3,366
Accrued and other current liabilities	10,277	9,604
Accrued federal fees	3,261	2,742
Sales tax liability	1,191	1,347
Notes payable	663	742
Capital leases	6,155	6,230
Deferred revenue	11,903	10,047
Total current liabilities	38,036	34,078
Revolving line of credit	32,594	32,594
Sales tax liability — less current portion	1,284	1,476
Notes payable — less current portion	0	318
Capital leases — less current portion	6,384	5,915
Other long-term liabilities	1,010	530
Total liabilities	79,308	74,911
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value; 5,000 shares authorized, no shares issued and outstanding at June 30, 2017 and December 31, 2016	0	0
Common stock, $0.001 par value; 450,000 shares authorized, 55,096 shares and 53,363 shares issued and outstanding at June 30, 2017 and December 31, 2016, respectively	55	53
Additional paid-in capital	207,813	196,555
Accumulated deficit	(175,713)	(166,280)
Total stockholders’ equity	32,155	30,328
Total liabilities and stockholders’ equity	$ 111,463	$ 105,239

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets - Parenthetical - $ / shares	Jun. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Preferred Stock, par value (in USD per share)	$ 0.001	$ 0.001
Preferred Stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred Stock, shares issued (in shares)	0	0
Preferred Stock, shares outstanding (in shares)	0	0
Common Stock, par value (in USD per share)	$ 0.001	$ 0.001
Common Stock, shares authorized (in shares)	450,000,000	450,000,000
Common Stock, shares issued (in shares)	55,095,711	53,363,013
Common Stock, shares outstanding (in shares)	55,095,711	53,363,013

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Revenue	$ 47,727	$ 38,886	$ 94,741	$ 76,901
Cost of revenue	20,273	16,764	40,244	33,374
Gross profit	27,454	22,122	54,497	43,527
Operating expenses:
Research and development	6,836	5,799	13,683	11,601
Sales and marketing	16,932	12,637	32,710	25,343
General and administrative	6,845	5,882	15,705	12,418
Total operating expenses	30,613	24,318	62,098	49,362
Loss from operations	(3,159)	(2,196)	(7,601)	(5,835)
Other income (expense), net:
Interest expense	(888)	(1,197)	(1,770)	(2,396)
Interest income and other	90	(33)	208	(78)
Total other income (expense), net	(798)	(1,230)	(1,562)	(2,474)
Loss before income taxes	(3,957)	(3,426)	(9,163)	(8,309)
Provision for income taxes	50	42	99	70
Net loss	$ (4,007)	$ (3,468)	$ (9,262)	$ (8,379)
Net loss per share:
Basic and diluted (in USD per share)	$ (0.07)	$ (0.07)	$ (0.17)	$ (0.16)
Shares used in computing net loss per share:
Basic and diluted (in shares)	54,723	52,143	54,208	51,760
Comprehensive Loss:
Net loss and comprehensive loss	$ (4,007)	$ (3,468)	$ (9,262)	$ (8,379)

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net loss	$ (9,262)	$ (8,379)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	4,365	4,163
Provision for doubtful accounts	45	41
Stock-based compensation	6,983	4,408
Loss (gain) on disposal of property and equipment	(13)	2
Non-cash adjustment on investment	(161)	0
Amortization of debt discount and issuance costs	40	178
Accretion of interest	10	0
Others	(1)	(7)
Changes in operating assets and liabilities:
Accounts receivable	(2,426)	(245)
Prepaid expenses and other current assets	(4,106)	(1,206)
Other assets	166	62
Accounts payable	1,187	357
Accrued and other current liabilities	909	1,389
Accrued federal fees and sales tax liability	171	12
Deferred revenue	2,025	1,535
Other liabilities	311	(53)
Net cash provided by operating activities	243	2,257
Cash flows from investing activities:
Purchases of property and equipment	(1,178)	(568)
Increase in restricted cash	0	(60)
Net cash used in investing activities	(1,178)	(628)
Cash flows from financing activities:
Proceeds from exercise of common stock options	2,303	3,352
Proceeds from sale of common stock under ESPP	1,800	792
Repayments of notes payable	(400)	(3,563)
Payments of capital leases	(3,741)	(3,056)
Net cash used in financing activities	(38)	(2,475)
Net decrease in cash and cash equivalents	(973)	(846)
Cash and cash equivalents:
Beginning of period	58,122	58,484
End of period	57,149	57,638
Non-cash investing and financing activities:
Equipment obtained under capital lease	4,012	3,352
Equipment purchased and unpaid at period-end	$ 51	$ 102

Description of Business and Sum

Description of Business and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Summary of Significant Accounting Policies	Description of Business and Summary of Significant Accounting Policies Five9, Inc. and its wholly-owned subsidiaries (the “Company”) is a provider of cloud software for contact centers. The Company was incorporated in Delaware in 2001 and is headquartered in San Ramon, California. The Company has offices in Europe and Asia, which primarily provide research, development, sales, marketing, and client support services. Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 . All intercompany transactions and balances have been eliminated in consolidation. Use of Estimates The preparation of condensed consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. The significant estimates made by management affect revenue, the allowance for doubtful accounts, intangible assets, goodwill, loss contingencies, including the Company’s accrual for federal fees and sales tax liability, accrued liabilities, stock-based compensation, provision for income taxes and uncertain tax positions. Management periodically evaluates such estimates and they are adjusted prospectively based upon such periodic evaluation. Actual results could differ from those estimates. Significant Accounting Policies The Company’s significant accounting policies are disclosed in its Annual Report on Form 10-K for the year ended December 31, 2016 . During the six months ended June 30, 2017 , there were no changes to the Company's significant accounting policies. Recently Adopted Accounting Pronouncements In March 2016, the FASB issued ASU No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting . This ASU simplifies several aspects of the accounting for share-based payment transactions, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. The guidance was effective for the Company beginning in the first quarter of 2017, with early application permitted. Beginning in Q1 2017, the Company accounted for forfeitures as they occurred, rather than by estimating expected forfeitures. The net effect of this change was recognized as a $0.2 million reduction to accumulated deficit in the condensed consolidated financial statements. Upon adoption of the new standard, all excess tax benefits and tax deficiencies (including tax benefits of dividends on share-based payment awards) are recognized as income tax expense or benefit in the income statement. The tax effects of exercised or vested awards are treated as discrete items in the reporting period in which they occur. The Company also recognizes excess tax benefits regardless of whether the benefit reduces taxes payable in the current period. The Company has applied the modified retrospective adoption approach beginning January 1, 2017 and prior periods have not been adjusted. As a result, the Company established a net operating loss deferred tax asset of $5.3 million to account for prior period excess tax benefits through retained earnings, however an offsetting valuation allowance of $5.3 million was also established through retained earnings because it is not more likely than not that the deferred tax asset will be realized due to historical and expected future losses, such that there is no impact on the Company’s condensed consolidated financial statements. Recent Accounting Pronouncements Not Yet Effective In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which requires measurement and recognition of expected credit losses for certain types of financial assets held. ASU 2016-13 is effective for the Company in its first quarter of 2020, and earlier adoption is permitted beginning in the first quarter of 2019. The Company is currently evaluating the impact of ASU 2016-13 on its consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) . Under the new guidance, a lessee will be required to recognize assets and liabilities for both finance, or capital, and operating leases with lease terms of more than 12 months. The ASU also will require disclosures to help investors and other financial statement users better understand the amount, timing, and uncertainty of cash flows arising from leases. Lessor accounting will remain largely unchanged from current GAAP. In transition, lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach that includes a number of optional practical expedients that entities may elect to apply. This guidance is effective for the Company beginning in the first quarter of 2019. Early adoption is permitted. The Company is currently assessing the effect the guidance will have on its consolidated financial statements. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers: Topic 606 and issued subsequent amendments to the initial guidance in August 2015, March 2016, April 2016 and May 2016 within ASU 2015-04, ASU 2016-08, ASU 2016-10 and ASU 2016-12, respectively (ASU 2014-09, ASU 2015-04, ASU 2016-08, ASU 2016-10 and ASU 2016-12 collectively, Topic 606). Topic 606 requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers and will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. Topic 606 defines a five-step process to achieve this core principle and, in doing so, it is possible more judgment and estimates may be required within the revenue recognition process than are required under existing GAAP. Topic 606 is effective for the Company's annual and interim reporting periods beginning January 1, 2018 using either a retrospective or a cumulative effect transition method. The Company has developed an implementation plan to adopt this new guidance. As part of this plan, the Company is currently assessing the impact of the new guidance on its results of operations. Based on procedures performed to date, nothing has come to the Company's attention that would indicate that the adoption of Topic 606 will have a material impact on the timing of revenue, but the Company has noted the potential for a material impact to commission expense. The Company will continue to evaluate this assessment in 2017. The Company intends to adopt Topic 606 on January 1, 2018. The Company has not yet selected a transition method, but expects to do so in the third quarter of 2017 upon completion of further analysis.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company carries cash equivalents consisting of money market funds at fair value on a recurring basis. Fair value is based on the price that would be received from selling an asset in an orderly transaction between market participants at the measurement date. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement: Level 1 — Observable inputs which include unadjusted quoted prices in active markets for identical assets. Level 2 — Observable inputs other than Level 1 inputs, such as quoted prices for similar assets, quoted prices for identical or similar assets in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the asset. Level 3 — Unobservable inputs that are supported by little or no market activity and that are based on management’s assumptions, including fair value measurements determined by using pricing models, discounted cash flow methodologies or similar techniques. The fair value of assets carried at fair value was determined using the following inputs (in thousands): June 30, 2017 Total Level 1 Level 3 Assets Cash equivalents Money market funds $ 20,038 $ 20,038 $ — Other Assets Embedded conversion option held for investment $ 917 $ — $ 917 December 31, 2016 Total Level 1 Level 3 Assets Cash equivalents Money market funds $ 20,069 $ 20,069 $ — Other Assets Embedded conversion option held for investment $ 873 $ — $ 873 Fair Value Measured and Recorded Using Significant Unobservable Inputs (Level 3) (in thousands): June 30, 2017 Beginning balance $ 873 Total gains included in earnings 44 Ending balance $ 917 The valuation of an embedded conversion option held for investment with a convertible note was performed using a Black-Scholes option-pricing model which relies primarily on estimates of expected term, volatility, risk-free rate, and dividends related to our investment in a privately-held company, or the investee. The most significant unobservable inputs used in the determination of estimated fair value of the option are the estimates of share price and volatility, driven by the investee's ability to meet financial targets, and which directly correlates to the fair value recognized in other non-current assets within the condensed consolidated balance sheets. The fair value of this asset is estimated quarterly by management based on inputs received from the investee's management using the excess earnings method under the income approach. Potential valuation adjustments are made as the progress toward achieving financial targets becomes determinable, with the impact of such adjustments being recorded to 'Interest income and other' in our condensed consolidated statements of operations and comprehensive loss. During the six months ended June 30, 2017 , there were no transfers in or out of Level 3 from other levels in the fair value hierarchy. There were no assets or liabilities measured at fair value on a non-recurring basis as of June 30, 2017 .

Financial Statement Components

Financial Statement Components	6 Months Ended
	Jun. 30, 2017
Financial Statement Components [Abstract]
Financial Statement Components	Financial Statement Components Cash and cash equivalents consisted of the following (in thousands): June 30, December 31, Cash $ 37,111 $ 38,053 Money market funds 20,038 20,069 Cash and cash equivalents $ 57,149 $ 58,122 Accounts receivable, net consisted of the following (in thousands): June 30, December 31, Trade accounts receivable $ 15,147 $ 12,640 Unbilled trade accounts receivable, net of advance client deposits 1,144 1,253 Allowance for doubtful accounts (10 ) (12 ) Accounts receivable, net $ 16,281 $ 13,881 Prepaid expenses and other current assets consisted of the following (in thousands): June 30, December 31, Prepaid expenses $ 3,326 $ 2,199 Other current assets 3,748 809 Prepaid expenses and other current assets $ 7,074 $ 3,008 Property and equipment, net consisted of the following (in thousands): June 30, December 31, Computer and network equipment $ 41,221 $ 37,664 Computer software 6,198 5,133 Internal-use software development costs 500 475 Furniture and fixtures 1,214 1,130 Leasehold improvements 632 624 Property and equipment 49,765 45,026 Accumulated depreciation and amortization (34,109 ) (30,338 ) Property and equipment, net $ 15,656 $ 14,688 Depreciation and amortization expense associated with property and equipment was $2.2 million and $4.1 million for the three and six months ended June 30, 2017 , respectively, and $1.9 million and $3.9 million for the three and six months ended June 30, 2016 , respectively. Property and equipment capitalized under capital lease obligations consist primarily of computer and network equipment and was as follows (in thousands): June 30, December 31, Gross $ 41,346 $ 35,504 Less: accumulated depreciation and amortization (28,338 ) (23,128 ) Total $ 13,008 $ 12,376 Accrued and other current liabilities consisted of the following (in thousands): June 30, December 31, Accrued compensation and benefits $ 8,608 $ 7,456 Accrued expenses 1,669 2,148 Accrued and other current liabilities $ 10,277 $ 9,604

Intangible Assets

Intangible Assets	6 Months Ended
	Jun. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	Intangible Assets The components of intangible assets were as follows (in thousands): June 30, 2017 December 31, 2016 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technology $ 2,460 $ (1,302 ) $ 1,158 $ 2,460 $ (1,126 ) $ 1,334 Customer relationships 520 (385 ) 135 520 (333 ) 187 Domain names 50 (37 ) 13 50 (32 ) 18 Non-compete agreements 140 (140 ) 0 140 (140 ) 0 Total $ 3,170 $ (1,864 ) $ 1,306 $ 3,170 $ (1,631 ) $ 1,539 Amortization expense related to intangible assets was $0.1 million and $0.2 million for the three and six months ended June 30, 2017 , respectively, and $0.1 million and $0.3 million for the three and six months ended June 30, 2016 , respectively. As of June 30, 2017 , the expected future amortization expense for intangible assets was as follows (in thousands): Period Expected Future Amortization Expense 2017 233 2018 442 2019 351 2020 280 Total $ 1,306

Debt

Debt	6 Months Ended
	Jun. 30, 2017
Debt Disclosure [Abstract]
Debt	Debt 2016 Loan and Security Agreement On August 1, 2016, or the Effective Date, the Company entered into a loan and security agreement, or the 2016 Loan and Security Agreement, with the lenders party thereto and City National Bank, as agent for such lenders. The 2016 Loan and Security Agreement provides for a revolving line of credit, or the New Revolving Credit Facility, of up to $50.0 million and matures on August 1, 2019. On the Effective Date, the Company borrowed $32.6 million under the 2016 Loan and Security Agreement. The proceeds were used to extinguish existing indebtedness under all prior Loan and Security Agreements and will be used for working capital and other general corporate purposes. Loans under the 2016 Loan and Security Agreement bear a variable annual interest rate of the prime rate plus 0.50% , subject to a 0.25% increase if the Company's adjusted EBITDA is negative at the end of any fiscal quarter. The Company has agreed to pay a fee of 0.25% per annum on the unused portion of the New Revolving Credit Facility as well as an anniversary fee of $31,250 on each of the first and second anniversaries of the Effective Date. The Company is accreting the total estimation of unused fees and anniversary fees evenly over the full term of the 2016 Loan and Security Agreement. Under the terms of the 2016 Loan and Security Agreement, the outstanding balance cannot exceed the Company’s trailing four months of MRR (monthly recurring revenue including subscription and usage) multiplied by the average trailing 12 month dollar based retention rate (calculated on the same basis as in the Company’s periodic reports filed with the Securities and Exchange Commission). As of June 30, 2017 , the outstanding principal balance under the 2016 Loan and Security Agreement was $32.6 million , which is included in 'Revolving line of credit' in the condensed consolidated balance sheets. As of June 30, 2017 , the amount available for additional borrowings was $17.4 million . The Company incurred approximately $0.2 million in fees that were directly attributable to the issuance of this credit facility. These costs are deferred and included within 'Prepaid expenses and other current assets' and 'Other assets' in the Company's condensed consolidated balance sheets and being amortized to interest expense on a straight-line basis over three years starting from the Effective Date of the New Revolving Credit Facility. The obligations of the Company under the 2016 Loan and Security Agreement are guaranteed by the Company’s subsidiary, Five9 Acquisition. The Company’s obligations under the 2016 Loan and Security Agreement and Five9 Acquisition’s obligations under its guaranty are secured by a first priority perfected security interest in and lien on substantially all of the Company’s and Five9 Acquisition's assets. The 2016 Loan and Security Agreement contains certain customary covenants, including the requirement that the Company maintain $25.0 million of unrestricted cash deposited with the lenders for the term of the agreement, a minimum liquidity ratio of unrestricted cash and accounts receivable to the outstanding amounts under the 2016 Loan and Security Agreement, as well as customary events of default. Under the 2016 Loan and Security Agreement, the Company is also prohibited from declaring dividends or making other distributions on capital stock. The Company was in compliance with these covenants as of June 30, 2017 . The Company recorded a $1.0 million loss on extinguishment of debt in the third quarter of 2016 under the 2013 Loan and Security Agreement and the 2014 Loan and Security Agreement (each as described below). The loss was comprised of $0.4 million in prepayment penalties, a $0.4 million write-off of unamortized debt discounts, and a $0.2 million write-off of unamortized debt issuance costs. 2013 Loan and Security Agreement Prior to entering into the 2016 Loan and Security Agreement on August 1, 2016, the Company had a revolving line of credit of up to $20.0 million , or the Prior Revolving Credit Facility, under a loan and security agreement with a lender, which was entered into in March 2013 and last amended in December 2014, or the 2013 Loan and Security Agreement. The Prior Revolving Credit Facility carried a variable annual interest rate of the prime rate plus 0.50% and would have matured on December 1, 2016. The 2013 Loan and Security Agreement was collateralized by substantially all the assets of the Company. The balance outstanding could not exceed the lesser of (i) $20.0 million or (ii) an amount equal to the Company’s monthly recurring revenue for the three months prior multiplied by the average Dollar-Based Retention Rate over the prior twelve months, less the amount accrued for the Company’s Universal Service Fund (“USF”) obligation (accrued federal fees). As of August 1, 2016, the Company had canceled and paid back all amounts due under the Prior Revolving Credit Facility. In connection with its acquisition of SoCoCare in October 2013, the Company also borrowed $5.0 million under a term loan, or the Term Loan, under the 2013 Loan and Security Agreement in October 2013. Monthly interest-only payments were due on the advance at the prime rate plus 1.50% through September 2014. Principal and interest payments were due in equal monthly installments from October 2014 through the maturity of the Term Loan in March 2017. As of August 1, 2016, the Company had canceled and paid back all amounts due under the Term Loan. The 2013 Loan and Security Agreement contained certain covenants, including the requirement that the Company maintain $7.5 million of cash deposited with the lender for the term of the 2013 Loan and Security Agreement. The Company was in compliance with these covenants through the cancellation date of August 1, 2016. The 2013 Loan and Security Agreement remained senior to other debt, including the debt issued under the 2014 Loan and Security Agreement discussed below. 2014 Loan and Security Agreement Prior to entering into the 2016 Loan and Security Agreement on August 1, 2016, the Company had a term loan facility of $30.0 million with a syndicate of two lenders, or Lenders, which was entered into in February 2014 and amended in December 2014 and February 2015, or the 2014 Loan and Security Agreement. The term loan facility was available to the Company in tranches. The first tranche for $20.0 million was advanced upon entering into the agreement. The remaining $10.0 million was available for drawdown by the Company until February 20, 2016 in $1.0 million increments, which expired on February 20, 2016. The Company incurred $0.4 million in debt costs in connection with borrowing the first tranche in February 2014. The term loan bore interest at a variable per annum rate equal to the greater of 10% or LIBOR plus 9% . Interest was due and payable on the last business day of each month during the term of the loan commencing in February 2014. Monthly principal payments were due beginning in February 2016 based on 1/60th of the outstanding balance at that time and would continue until all remaining principal outstanding under the term loan became due and payable in February 2019. As of August 1, 2016, the Company had canceled and paid back all borrowings under the 2014 Loan and Security Agreement. The term loan was secured by substantially all the assets of the Company and was subordinate to the 2013 Loan and Security Agreement. The 2014 Loan and Security Agreement contained certain covenants and included the occurrence of a material adverse event, as defined in the agreement and determined by the Lenders, as an event of default. The Company was in compliance with these covenants through the effective cancellation date of August 1, 2016. In connection with entering into the 2014 Loan and Security Agreement, the Company issued to the Lenders warrants to purchase 177,865 shares of common stock at $10.12 per share, which vest and become exercisable over a ten year term from the date of issuance, based on amounts drawn under the $30.0 million term loan facility. Based on the drawdown of $20.0 million in February 2014, 118,577 shares of common stock issuable under the warrants vested and are exercisable by the Lenders. The fair value of these vested warrants of $1.0 million was recorded as a discount against the debt proceeds and was being recognized as additional interest expense over the term of the loan. The remaining 59,288 shares of common stock issuable under the warrants pertaining to the undrawn $10.0 million did not vest and were no longer exercisable on February 20, 2016 when the $10.0 million was no longer available for borrowing. Promissory Note In July 2013, the Company issued a promissory note to the Universal Service Administrative Company, or USAC, for $4.1 million in principal amount as a financing arrangement for that amount of accrued federal fees. The promissory note carried a fixed annual interest rate of 12.75% and was repayable in 42 equal monthly installments of principal and interest beginning in August 2013. As of December 31, 2016 , approximately $0.1 million of this promissory note was outstanding and is included as notes payable in the accompanying condensed consolidated balance sheets. As of June 30, 2017 , the promissory note was fully paid. FCC Civil Penalty In June 2015, the Company entered into a consent decree with the Federal Communications Commission, or FCC, Enforcement Bureau (Note 9), in which the Company agreed to pay a civil penalty of $2.0 million to the U.S. Treasury in twelve equal quarterly installments starting in July 2015 without interest. As a result, the Company discounted the $2.0 million liability, which was accrued in the third quarter of 2014 for the then tentative civil penalty, to its present value of $1.7 million at an annual interest rate of 12.75% to reflect the imputed interest and reclassified this discounted liability from 'Accrued federal fees' to 'Notes payable.' The $0.3 million discount was recorded as a reduction to general and administrative expense in the three months ended June 30, 2015 and is being recognized as interest expense over the payment term of the civil penalty. As of June 30, 2017 and December 31, 2016 , the outstanding civil penalty payable was $0.7 million and $1.0 million , respectively, of which the net carrying value was $0.6 million and $0.9 million , respectively, and is included as 'Notes payable' in the accompanying condensed consolidated balance sheets. As of June 30, 2017 and December 31, 2016 , the Company’s outstanding debt is summarized as follows (in thousands): June 30, 2017 December 31, 2016 Promissory note to USAC — 120 FCC civil penalty 667 1,000 Total notes payable, gross 667 1,120 Less: discount (34 ) (79 ) Total notes payable, net carrying value 633 1,041 Revolving line of credit 32,594 32,594 Interest accretion under 2016 line of credit $ 30 $ 19 Total debt, net carrying value $ 33,257 $ 33,654 Less: current portion of debt * (663 ) (742 ) Total debt, less current portion ** 32,594 32,912 * Included in ‘Notes payable’ in the condensed consolidated balance sheets. ** Included in ‘Notes payable - less current portion’ and 'Revolving line of credit — less current portion' in the condensed consolidated balance sheets. Maturities of the Company’s outstanding debt as of June 30, 2017 are as follows (in thousands): Period Amount to Mature 2017 333 2018 334 2019 32,594 Total $ 33,261

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2017
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Capital Structure The Company is authorized to issue 450,000,000 shares of common stock with a par value of $0.001 per share. As of June 30, 2017 and December 31, 2016 , the Company had 55,095,711 and 53,363,013 shares of common stock issued and outstanding, respectively. The Company is also authorized to designate and issue up to 5,000,000 shares of preferred stock with a par value of $0.001 per share in one or more series without stockholder approval and to fix the rights, preferences, privileges and restrictions thereof. As of June 30, 2017 and December 31, 2016 , the Company had no shares of preferred stock issued and outstanding. Warrants As of June 30, 2017 and December 31, 2016 , the Company had outstanding warrants to purchase 13,017 and 131,597 shares of common stock, respectively, with a weighted-average exercise price of $6.93 per share and $9.80 per share, respectively. Most of these warrants expire on October 18, 2023 . Common Stock Reserved for Future Issuance Shares of common stock reserved for future issuance related to outstanding equity awards, common stock warrants, and employee equity incentive plans were as follows (in thousands): June 30, 2017 Stock options outstanding 4,791 Restricted stock units outstanding 2,412 Shares available for future grant under 2014 Plan 7,590 Shares available for future issuance under ESPP 1,495 Common stock warrants outstanding 13 Total shares of common stock reserved 16,301 Equity Incentive Plans Prior to its initial public offering (“IPO”), the Company granted stock options under its Amended and Restated 2004 Equity Incentive Plan, as amended (the “2004 Plan”). In March 2014, the Company’s board of directors and stockholders approved the 2014 Equity Incentive Plan (“2014 Plan”) and 5,300,000 shares of common stock were reserved for issuance under the 2014 Plan. In addition, on the first day of each year beginning in 2015 and ending in 2024, the 2014 Plan provides for an annual automatic increase to the shares reserved for issuance in an amount equal to 5% of the total number of shares outstanding on December 31st of the preceding calendar year or a lesser number as determined by the Company’s board of directors. Pursuant to the automatic annual increase, 2,668,150 and 2,558,231 additional shares were reserved under the 2014 Plan on January 1, 2017 and 2016, respectively. No further grants were made under the 2004 Plan once the 2014 Plan became effective on April 3, 2014. Upon the effectiveness of the 2014 Plan, all shares reserved for future issuance under the 2004 Plan became available for issuance under the 2014 Plan. After the IPO, any forfeited or expired shares that would have otherwise returned to the 2004 Plan instead return to the 2014 Plan. As of June 30, 2017 , 7,589,526 shares of common stock were available for future grant under the 2014 Plan. The 2004 Plan and the 2014 Plan are described in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 . Stock Options A summary of the Company’s stock option activity during the six months ended June 30, 2017 is as follows (in thousands, except years and per share data): Number of Weighted Weighted Aggregate Outstanding as of December 31, 2016 5,556 $ 5.23 Options granted (weighted average grant date fair value of $8.01 per share) 485 16.52 Options exercised (1,123 ) 2.05 Options forfeited or expired (127 ) 12.86 Outstanding as of June 30, 2017 4,791 $ 6.91 6.4 $ 70,014 The Company has computed the aggregate intrinsic value amounts disclosed in the above table based on the difference between the exercise price of the options and the closing market price of the Company’s common stock of $21.52 per share as of June 30, 2017 for all in-the-money options outstanding. Restricted Stock Units A summary of the Company's restricted stock unit ("RSU") activity during the six months ended June 30, 2017 is as follows (in thousands, except per share data): Number of Shares Weighted Average Grant Date Fair Value Per Share Outstanding as of December 31, 2016 2,019 $ 7.65 RSUs granted 921 16.83 RSUs vested and released (422 ) 8.27 RSUs forfeited (106 ) 11.09 Outstanding as of June 30, 2017 2,412 $ 10.85 Employee Stock Purchase Plan The Company's 2014 Employee Stock Purchase Plan ("ESPP") became effective on April 3, 2014 and is described in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 . The number of shares of common stock originally reserved for issuance under the ESPP was 880,000 shares, which will increase automatically each year, beginning on January 1, 2015 and continuing through January 1, 2024, by the lesser of (i) 1% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year; (ii) 1,000,000 shares of common stock (subject to adjustment to reflect any split or combination of the Company’s common stock); or (iii) such lesser number as determined by the Company’s board of directors. Pursuant to the automatic annual increase, 533,630 and 511,646 additional shares were reserved under the ESPP on January 1, 2017 and 2016, respectively. As of June 30, 2017 , 1,494,632 shares of common stock were available for future grants under the ESPP. One purchase event occurred during the three and six months ended June 30, 2017 as follows: 141,222 shares were purchased on May 15, 2017 at a price of $12.75 per share under the ESPP. Stock-Based Compensation Stock-based compensation expenses for the three and six months ended June 30, 2017 and 2016 were as follows (in thousands): Three Months Ended Six Months Ended June 30, 2017 June 30, 2016 June 30, 2017 June 30, 2016 Cost of revenue $ 575 $ 329 $ 1,009 $ 594 Research and development 801 528 1,438 963 Sales and marketing 1,224 544 2,152 978 General and administrative 1,254 1,013 2,384 1,873 Total stock-based compensation $ 3,854 $ 2,414 $ 6,983 $ 4,408 As of June 30, 2017 , unrecognized stock-based compensation expenses by award type and their expected weighted-average recognition periods are summarized in the following table (in thousands, except years). Stock Option RSU ESPP Unrecognized stock-based compensation expense $ 7,196 $ 23,823 $ 570 Weighted-average amortization period 2.8 years 3.0 years 0.4 years The Company recognizes stock-based compensation expense that is calculated based upon awards that have vested, reduced for actual forfeitures. All stock-based compensation for equity awards granted to employees and non-employee directors is measured based on the grant date fair value of the award. The Company values RSUs at the closing market price of its common stock on the date of grant. The Company estimates the fair value of each stock option and purchase right under the ESPP granted to employees on the date of grant using the Black-Scholes option-pricing model and using the assumptions noted in the below table. The weighted-average assumptions used to value stock options granted during the three and six months ended June 30, 2017 and 2016 were as follows: Stock Options Three Months Ended Six Months Ended June 30, 2017 June 30, 2016 June 30, 2017 June 30, 2016 Expected term (years) 6.1 6.1 6.2 6.0 Volatility 49% 48% 49% 48% Risk-free interest rate 2.0% 1.2% 2.0% 1.5% Dividend yield — — — —

Net Loss Per Share

Net Loss Per Share	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing net loss by the weighted average number of common shares outstanding during the period, and excludes any dilutive effects of employee stock-based awards and warrants. Diluted net income per share is computed giving effect to all potentially dilutive common shares, including common stock issuable upon exercise of stock options and warrants and vesting of restricted stock. As the Company had net losses for the three and six months ended June 30, 2017 and 2016 , all potentially issuable common shares were determined to be anti-dilutive. The following table presents the calculation of basic and diluted net loss per share (in thousands, except per share data). Three Months Ended Six Months Ended June 30, 2017 June 30, 2016 June 30, 2017 June 30, 2016 Net loss $ (4,007 ) $ (3,468 ) $ (9,262 ) $ (8,379 ) Weighted-average shares used in computing basic and diluted net loss per share 54,723 52,143 54,208 51,760 Basic and diluted net loss per share $ (0.07 ) $ (0.07 ) $ (0.17 ) $ (0.16 ) The following securities were excluded from the calculation of diluted net loss per share attributable to common stockholders because their effect would have been anti-dilutive for the periods presented (in thousands). June 30, 2017 June 30, 2016 Stock options 4,791 5,831 Restricted stock units 2,412 2,228 ESPP — 147 Common stock warrants 13 132 Total 7,216 8,338

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The provision for income taxes for the three and six months ended June 30, 2017 was approximately $50 thousand and $99 thousand , respectively. The provision for income taxes for the three and six months ended June 30, 2016 was approximately $42 thousand and $70 thousand , respectively. The provision for income taxes consisted primarily of foreign income taxes. For the three and six months ended June 30, 2017 and 2016 , the provision for income taxes differed from the statutory amount primarily due to the Company realizing no benefit for current year losses due to maintaining a full valuation allowance against its domestic net deferred tax assets. The realization of tax benefits of deferred tax assets is dependent upon future levels of taxable income, of an appropriate character, in the periods the items are expected to be deductible or taxable. Based on the available objective evidence, the Company does not believe it is more likely than not that the net deferred tax assets will be realizable. Accordingly, the Company has provided a full valuation allowance against the domestic net deferred tax assets as of June 30, 2017 and December 31, 2016 . The Company intends to maintain the remaining valuation allowance until sufficient positive evidence exists to support a reversal of, or decrease in, the valuation allowance. During the three and six months ended June 30, 2017 , there were no material changes to the total amount of unrecognized tax benefits.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments The Company’s principal commitments consist of future payment obligations under capital leases to finance data centers and other computer and networking equipment purchases, debt agreements (see Note 5), operating lease agreements for office space, research and development, and sales and marketing facilities, and agreements with third parties to provide co-location hosting, telecommunication usage and equipment maintenance services. These commitments as of December 31, 2016 are disclosed in the Company's Annual Report on Form 10-K for the year ended December 31, 2016 , and did not change materially during the six months ended June 30, 2017 except for the acquisition of certain additional data center and network equipment and software under multiple capital leases, and certain hosting and telecommunications agreements. As of June 30, 2017 , the total minimum future payment commitments under these capital leases added during the six months ended June 30, 2017 were approximately $4.7 million , of which $0.9 million is due during the remainder of 2017, with the remainder of $3.8 million due over approximately 31 months. The Company entered into various hosting and telecommunications agreements for terms of twenty-four to thirty-six months commencing on various dates in the first three quarters of 2017. These agreements require the Company to make monthly payments over the service term in exchange for certain network services. The Company's total minimum future payment commitments under these agreements are $4.1 million . Universal Services Fund Liability During the third quarter of 2012, the Company determined that based on its business activities, it is classified as a telecommunications service provider for regulatory purposes and it should make direct contributions to the federal USF and related funds based on revenues it receives from the resale of interstate and international telecommunications services. In order to comply with the obligation to make direct contributions, the Company made a voluntary self-disclosure to the FCC Enforcement Bureau and registered with the USAC, which is charged by the FCC with administering the USF. The Company filed exemption certificates with its wholesale telecommunications service providers in order to eliminate its obligation to reimburse such wholesale telecommunications service providers for their USF contributions calculated on services sold to the Company. In April 2013, the Company began remitting required contributions on a prospective basis directly to USAC. The Company’s registration with USAC subjects it to assessments for unpaid USF contributions, as well as interest thereon and civil penalties, due to its late registration and past failure to recognize its obligation as a USF contributor and as an international carrier. The Company will be required to pay assessments for periods prior to the Company’s registration. As of December 31, 2012, the total past due USF contribution being imposed by USAC and accrued by the Company for the period from 2003 through 2012 was $8.1 million , of which $4.7 million was undisputed and $3.4 million was disputed. The Company subsequently updated its filings and increased the liability related to 2008 through 2012 by $0.5 million , arriving at a new total of $3.9 million . In July 2013, the Company and USAC agreed to a financing arrangement for $4.1 million of the undisputed $4.7 million of the unpaid USF contributions whereby the Company issued to USAC a promissory note payable in the principal amount of the $4.1 million and paid off the remaining undisputed $0.6 million . The repayment terms of the promissory note payable are disclosed in Note 5 . As of December 31, 2016 , approximately $0.1 million of this promissory note was outstanding and is included as notes payable in the accompanying condensed consolidated balance sheets. As of June 30, 2017 , the promissory note was fully paid. With respect to the disputed portion, in 2013, the Company submitted two separate Requests for Review (a form of appeal) to the FCC's Wireline Competition Bureau challenging two aspects of USAC’s assessment of past due USF contributions for the period from 2003 through 2012. The first Request for Review challenged USAC’s assessment of liability for the period of 2003 through 2007, which was prior to the five year window during which we were required to maintain financial records for USF contribution purposes. The second Request for Review sought credit for the Company’s USF payments to its wholesale carriers during the period from 2008 through 2012. In January 2017, the FCC’s Wireline Competition Bureau ruled in favor of the Company regarding the principal for its payments to its wholesale carriers during 2008 through 2012, but not the interest or penalties on that principal, resulting in a reversal of $3.1 million to cost of revenue. USAC has not completed the administrative process of approving that $3.1 million credit, but it is fully anticipated to do so. In February 2017, the Company filed a third Request for Review disputing that portion of the decision by the FCC’s Wireline Competition Bureau that withheld credit for the interest and penalties on the back assessments for the period of 2008 through 2012. The FCC has not yet resolved the Company’s Request for Review challenging assessments for 2003 to 2007 or the Company’s Request for Review on the interest and penalties for the period of 2008 through 2012. If the pending disputes are not resolved in the Company’s favor, it is possible that the Company will be required to pay additional back assessments for one or both of those periods. As of June 30, 2017 , the accrued liability on the remaining disputed assessments is $2.8 million , which includes $0.8 million in USF assessment for the period of 2003 through 2007, $0.4 million for the interest and penalties on that assessment, and $1.6 million for the interest and penalties on the $3.1 million in since-credited prior payments to the Company’s wholesale carriers. As of December 31, 2016 , the accrued liability on the remaining disputed assessments is $2.5 million , which includes $0.8 million in USF assessment for the period of 2003 through 2007, $0.3 million for the interest and penalties on that assessment, and $1.4 million for the interest and penalties on the $3.1 million in since-credited prior payments to the Company’s wholesale carriers. For the three and six months ended June 30, 2017 , the Company recorded interest and penalty expenses of $0.2 million and $0.3 million , respectively, as a charge to general and administrative expense, which were related to its disputed unpaid USF obligations. On June 12, 2015, in connection with the Company’s disclosure to the FCC, the Company entered into a consent decree with the FCC Enforcement Bureau. In the consent decree, the Company agreed to pay a civil penalty of $2.0 million to the U.S. Treasury in twelve equal quarterly installments starting in July 2015 without interest (Note 5 ). In the third quarter of 2014, the Company accrued a $2.0 million liability for the then tentative civil penalty. The consent decree also requires the Company to adopt certain internal regulatory compliance monitoring and training requirements, and to report on the status of those compliance efforts to the FCC’s Enforcement Bureau for three years. The Company’s implementation of the internal regulatory compliance monitoring and training requirements was completed in August 2015, and its annual compliance reporting to the FCC will continue until June 2018. State and Local Taxes and Surcharges In April 2012, the Company commenced collecting and remitting sales taxes on sales of subscription services in all the U.S. states in which it determined it was obligated to do so. During the first quarter of 2015, the Company conducted an updated sales tax review of the taxability of sales of its subscription services. As a result, the Company determined that it may be obligated to collect and remit sales taxes on such sales in four additional states. Based on its best estimate of the probable sales tax liability in those four states relating to its sales of subscription services during the period 2011 through 2014, during the three months ended March 31, 2015, the Company recorded a general and administrative expense of $0.6 million as an immaterial out of period adjustment to accrue for such taxes. During 2013, the Company analyzed its activities and determined it may be obligated to collect and remit various state and local taxes and surcharges on its usage-based fees. The Company had not remitted state and local taxes on usage-based fees in any of the periods prior to 2014 and therefore accrued a sales tax liability for this contingency. In January 2014, the Company commenced paying such taxes and surcharges to certain state authorities. In June 2014, the Company commenced collecting state and local taxes or surcharges on usage-based fees from its clients on a current basis and remitting such taxes to the applicable U.S. state taxing authorities. During the three months ended June 30, 2017 , the Company made no payments for its contingent sales taxes on either usage-based fees or sales of subscription services. During the three months ended June 30, 2016 , the Company remitted $25 thousand for its contingent sales taxes on both usage-based fees and sales of subscription services. For the three months ended June 30, 2017 , the Company recognized a $0.1 million gain as an offset to general and administrative expense related to its estimated sales tax liability on both usage-based fees and sales of subscription services in the U.S. and Canada. For the three months ended June 30, 2016 , the Company recognized a $0.2 million gain as an offset to general and administrative expense related to its estimated sales tax liability on both usage-based fees and sales of subscription services in the U.S. and Canada, which was not being collected from its clients. As of June 30, 2017 and December 31, 2016 , the Company had total accrued liabilities of $1.8 million and $2.1 million , respectively, for such contingent sales taxes and surcharges that were not being collected from its clients but may be imposed by various taxing authorities, of which $0.5 million and $0.6 million were included in current “Sales tax liability” on the condensed consolidated balance sheets, respectively, and the remaining were included in non-current “Sales tax liability” on the condensed consolidated balance sheets. The Company’s estimate of the probable loss incurred under this contingency is based on its analysis of the source location of its usage-based fees and the regulations and rules in each tax jurisdiction. Legal Matters The Company is involved in various legal and regulatory matters arising in the normal course of business. In management’s opinion, resolution of these matters is not expected to have a material impact on the Company’s consolidated results of operations, cash flows, or its financial position. However, due to the uncertain nature of legal matters, an unfavorable resolution of a matter could materially affect the Company’s future consolidated results of operations, cash flows or financial position in a particular period. The Company expenses legal fees as incurred. The Company is currently involved in the following lawsuits as a defendant. Melcher Litigation On September 28, 2016, a complaint was filed in the United States District Court for the Southern District of California against Five9, Inc., or Five9, as the successor in interest to Face It, Corp., or Face It, and Lance Fried, a former Five9 employee who was the former Chief Executive Officer of Face It. The action, captioned Melcher, et al. v. Five9, Inc., et al., No. 16-cv-02440, or the Federal Lawsuit, was filed as a direct action by Carl Melcher, or Melcher, a purported former stockholder of Face It, and his related investment entity Melcher Family Limited Partnership, or MFLP. In the complaint, the plaintiffs alleged that Face It repurchased the plaintiffs’ stock in September 2013 before Five9 acquired Face It, and that in connection with the repurchase, Fried made material misstatements or omissions to Melcher, by failing to disclose that Face It allegedly was in concurrent discussions about a potential sale of the company to Five9. The complaint alleged violations of Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 and Rule 10b-5 promulgated thereunder, as well as various claims under state law and common law. The complaint sought to set aside Face It’s September 2013 stock repurchase from the plaintiffs, as well as an unspecified amount of damages and an award of attorney’s fees and costs, in addition to other relief. On November 8, 2016, the court entered an order staying the Federal Lawsuit and ordered the parties to proceed to arbitration of the dispute before the American Arbitration Association, or AAA. On November 16, 2016, Melcher and MFLP submitted a Demand for Arbitration to AAA against Five9, asserting claims identical to those alleged in the Federal Lawsuit. On March 31, 2017, Five9 reached a settlement with the plaintiffs that fully resolved the plaintiffs’ claims against Five9 and provided for mutual releases between the parties in exchange for a one-time payment by Five9 to the plaintiffs of $1.7 million. As a result of the settlement, the arbitration was closed, and on July 10, 2017, the plaintiffs filed an amended complaint in the Federal Lawsuit solely against Fried removing Five9 as a defendant. Five9 believes that it has indemnification rights against the former stockholders of Face It for losses it incurred in connection with the defense and resolution of this matter. NobelBiz Litigation On August 5, 2011, NobelBiz sent a letter to the Company asserting infringement of a patent related to virtual call centers. On April 3, 2012, NobelBiz filed a patent infringement lawsuit against the Company in the United States District Court for the Eastern District of Texas. The patent asserted in the complaint is different, but related, to the patent asserted in the original letter. The lawsuit, NobelBiz Inc. v. Five9, Inc., Case No. 6:12-cv-00243-LED, alleges that the Company’s local caller ID management service infringes United States Patent No. 8,135,122, or the ‘122 patent. The ‘122 patent, titled “System and Method for Modifying Communication Information (MCI),” issued on March 13, 2012, and according to the complaint is alleged to relate to “a system for processing a telephone call from a call originator (also referred to as a calling party) to a call target (also referred to as a receiving party), where the system accesses a database storing outgoing telephone numbers, selects a replacement telephone number from the outgoing telephone numbers based on the telephone number of the call target, and originates an outbound call to the call target with a modified outgoing caller identification (‘caller ID’).” NobelBiz seeks damages in the form of lost profits as well as injunctive relief. The lawsuit is one of several lawsuits filed by NobelBiz against various companies including TCN Inc., LiveVox, Inc. and Global Connect LLC. On March 28, 2013, the court granted the Company’s motion to transfer the case to the United States District Court for the Northern District of California. Subsequently, NobelBiz amended its complaint to add claims related to U.S. Patent No. 8,565,399, or the ‘399 patent, which is a continuation in the same family as the ‘122 patent and addresses the same technology. The Company responded to the complaint and amended complaint by asserting noninfringement and invalidity of the ‘122 and ‘399 patents. On January 16, 2015, the court issued an order regarding claim construction of the two patents-in-suit. On March 7, 2016, the court stayed the case pending an appeal in lawsuits involving NobelBiz, Global Connect and TCN that also involve the ‘122 and ‘399 patents. On July 19, 2017, the Federal Circuit Court of Appeal issued a ruling confirming the claim construction in Five9’s lawsuit and resolving the appeal in favor of Global Connect and TCN and against NobelBiz. The Company anticipates that the court will set a new schedule for the litigation in light of this ruling. The Company has investigated the claims alleged in the complaint and believes that it has good defenses to the claims. While the Company does not believe that it is probable that a loss has been incurred, the ultimate resolution of the matter could potentially result in a loss. Management’s best estimate of the low end of the range of the potential loss is zero. At this time, it is not possible to reasonably estimate the high end of the range of the potential loss, which could be material to the Company’s results of operations. Accordingly, the Company has not accrued a loss related to this matter. Indemnification Agreements In the ordinary course of business, the Company enters into agreements of varying scope and terms pursuant to which it agrees to indemnify clients, vendors, lessors, business partners and other parties with respect to certain matters, including, but not limited to, losses arising out of breach of such agreements, services to be provided by the Company or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with directors and certain officers and employees that will require it, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors, officers or employees. Other than as described below, no demands have been made upon the Company to provide indemnification under such agreements and there are no claims that it is aware of that could have a material effect on the consolidated balance sheet, consolidated statement of operations and comprehensive loss, or consolidated statements of cash flows. On October 27, 2016, the Company received notice from Lance Fried, a former officer and director of Face It, of his claim for indemnification by the Company (as successor in interest to Face It), and for advancement of all legal fees and expenses he incurs in connection with the defense of the Melcher litigation. See "Legal Matters" above. As of June 30, 2017, the Company had advanced Mr. Fried $62 thousand in connection with this claim; however, the Company disputes that Mr. Fried is entitled to advancement in connection with the Melcher litigation. On July 31, 2017, Mr. Fried filed a complaint against the Company in the Court of Chancery for the State of Delaware, in which he alleges that the Company breached advancement obligations to him. In the lawsuit, Mr. Fried seeks advancement of his legal fees and expenses in connection with the defense of the Melcher litigation, payment of his legal fees and expenses incurred in connection with his advancement action, and interest. The Company believes the action is without merit and intends to defend it vigorously. To the extent that it is ultimately determined that Mr. Fried is not entitled to indemnification, Mr. Fried has undertaken to reimburse the Company for all amounts advanced to him. In addition, the Company believes that it has indemnification rights against the former stockholders of Face It (including Mr. Fried) for all losses that are incurred by the Company in connection with the Melcher litigation, including without limitation, amounts incurred to indemnify or advance the legal fees and expenses of Mr. Fried pursuant to his indemnification claim against the Company.

Geographical Information

Geographical Information	6 Months Ended
	Jun. 30, 2017
Segment Reporting [Abstract]
Geographical Information	Geographical Information The following table is a summary of revenues by geographic region based on client billing address and has been estimated based on the amounts billed to clients during the periods presented (in thousands). Three Months Ended Six Months Ended June 30, 2017 June 30, 2016 June 30, 2017 June 30, 2016 United States $ 44,830 $ 36,104 $ 89,188 $ 71,697 International 2,897 2,782 5,553 5,204 Total revenue $ 47,727 $ 38,886 $ 94,741 $ 76,901 The following table summarizes total property and equipment, net in the respective locations (in thousands). June 30, 2017 December 31, 2016 United States $ 14,241 $ 13,025 International 1,415 1,663 Property and equipment, net $ 15,656 $ 14,688

Description of Business and S16

Description of Business and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 . All intercompany transactions and balances have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. The significant estimates made by management affect revenue, the allowance for doubtful accounts, intangible assets, goodwill, loss contingencies, including the Company’s accrual for federal fees and sales tax liability, accrued liabilities, stock-based compensation, provision for income taxes and uncertain tax positions. Management periodically evaluates such estimates and they are adjusted prospectively based upon such periodic evaluation. Actual results could differ from those estimates.
Recently Adopted Accounting Pronouncements and Recent Accounting Pronouncements Not Yet Effective	Recently Adopted Accounting Pronouncements In March 2016, the FASB issued ASU No. 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting . This ASU simplifies several aspects of the accounting for share-based payment transactions, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. The guidance was effective for the Company beginning in the first quarter of 2017, with early application permitted. Beginning in Q1 2017, the Company accounted for forfeitures as they occurred, rather than by estimating expected forfeitures. The net effect of this change was recognized as a $0.2 million reduction to accumulated deficit in the condensed consolidated financial statements. Upon adoption of the new standard, all excess tax benefits and tax deficiencies (including tax benefits of dividends on share-based payment awards) are recognized as income tax expense or benefit in the income statement. The tax effects of exercised or vested awards are treated as discrete items in the reporting period in which they occur. The Company also recognizes excess tax benefits regardless of whether the benefit reduces taxes payable in the current period. The Company has applied the modified retrospective adoption approach beginning January 1, 2017 and prior periods have not been adjusted. As a result, the Company established a net operating loss deferred tax asset of $5.3 million to account for prior period excess tax benefits through retained earnings, however an offsetting valuation allowance of $5.3 million was also established through retained earnings because it is not more likely than not that the deferred tax asset will be realized due to historical and expected future losses, such that there is no impact on the Company’s condensed consolidated financial statements. Recent Accounting Pronouncements Not Yet Effective In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which requires measurement and recognition of expected credit losses for certain types of financial assets held. ASU 2016-13 is effective for the Company in its first quarter of 2020, and earlier adoption is permitted beginning in the first quarter of 2019. The Company is currently evaluating the impact of ASU 2016-13 on its consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) . Under the new guidance, a lessee will be required to recognize assets and liabilities for both finance, or capital, and operating leases with lease terms of more than 12 months. The ASU also will require disclosures to help investors and other financial statement users better understand the amount, timing, and uncertainty of cash flows arising from leases. Lessor accounting will remain largely unchanged from current GAAP. In transition, lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach that includes a number of optional practical expedients that entities may elect to apply. This guidance is effective for the Company beginning in the first quarter of 2019. Early adoption is permitted. The Company is currently assessing the effect the guidance will have on its consolidated financial statements. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers: Topic 606 and issued subsequent amendments to the initial guidance in August 2015, March 2016, April 2016 and May 2016 within ASU 2015-04, ASU 2016-08, ASU 2016-10 and ASU 2016-12, respectively (ASU 2014-09, ASU 2015-04, ASU 2016-08, ASU 2016-10 and ASU 2016-12 collectively, Topic 606). Topic 606 requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers and will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. Topic 606 defines a five-step process to achieve this core principle and, in doing so, it is possible more judgment and estimates may be required within the revenue recognition process than are required under existing GAAP. Topic 606 is effective for the Company's annual and interim reporting periods beginning January 1, 2018 using either a retrospective or a cumulative effect transition method. The Company has developed an implementation plan to adopt this new guidance. As part of this plan, the Company is currently assessing the impact of the new guidance on its results of operations. Based on procedures performed to date, nothing has come to the Company's attention that would indicate that the adoption of Topic 606 will have a material impact on the timing of revenue, but the Company has noted the potential for a material impact to commission expense. The Company will continue to evaluate this assessment in 2017. The Company intends to adopt Topic 606 on January 1, 2018. The Company has not yet selected a transition method, but expects to do so in the third quarter of 2017 upon completion of further analysis.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Schedule of Assets Carried at Fair Value	The fair value of assets carried at fair value was determined using the following inputs (in thousands): June 30, 2017 Total Level 1 Level 3 Assets Cash equivalents Money market funds $ 20,038 $ 20,038 $ — Other Assets Embedded conversion option held for investment $ 917 $ — $ 917 December 31, 2016 Total Level 1 Level 3 Assets Cash equivalents Money market funds $ 20,069 $ 20,069 $ — Other Assets Embedded conversion option held for investment $ 873 $ — $ 873
Fair Value Measured and Recorded Using Significant Unobservable Inputs	Fair Value Measured and Recorded Using Significant Unobservable Inputs (Level 3) (in thousands): June 30, 2017 Beginning balance $ 873 Total gains included in earnings 44 Ending balance $ 917

Financial Statement Components

Financial Statement Components (Tables)	6 Months Ended
	Jun. 30, 2017
Financial Statement Components [Abstract]
Schedule of Cash and Cash Equivalents	Cash and cash equivalents consisted of the following (in thousands): June 30, December 31, Cash $ 37,111 $ 38,053 Money market funds 20,038 20,069 Cash and cash equivalents $ 57,149 $ 58,122
Schedule of Accounts Receivable	Accounts receivable, net consisted of the following (in thousands): June 30, December 31, Trade accounts receivable $ 15,147 $ 12,640 Unbilled trade accounts receivable, net of advance client deposits 1,144 1,253 Allowance for doubtful accounts (10 ) (12 ) Accounts receivable, net $ 16,281 $ 13,881
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consisted of the following (in thousands): June 30, December 31, Prepaid expenses $ 3,326 $ 2,199 Other current assets 3,748 809 Prepaid expenses and other current assets $ 7,074 $ 3,008
Schedule of Property and Equipment	Property and equipment, net consisted of the following (in thousands): June 30, December 31, Computer and network equipment $ 41,221 $ 37,664 Computer software 6,198 5,133 Internal-use software development costs 500 475 Furniture and fixtures 1,214 1,130 Leasehold improvements 632 624 Property and equipment 49,765 45,026 Accumulated depreciation and amortization (34,109 ) (30,338 ) Property and equipment, net $ 15,656 $ 14,688
Schedule of Capital Leased Property and Equipment	Property and equipment capitalized under capital lease obligations consist primarily of computer and network equipment and was as follows (in thousands): June 30, December 31, Gross $ 41,346 $ 35,504 Less: accumulated depreciation and amortization (28,338 ) (23,128 ) Total $ 13,008 $ 12,376
Schedule of Accrued and Other Current Liabilities	Accrued and other current liabilities consisted of the following (in thousands): June 30, December 31, Accrued compensation and benefits $ 8,608 $ 7,456 Accrued expenses 1,669 2,148 Accrued and other current liabilities $ 10,277 $ 9,604

Intangible Assets (Tables)

Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets	The components of intangible assets were as follows (in thousands): June 30, 2017 December 31, 2016 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technology $ 2,460 $ (1,302 ) $ 1,158 $ 2,460 $ (1,126 ) $ 1,334 Customer relationships 520 (385 ) 135 520 (333 ) 187 Domain names 50 (37 ) 13 50 (32 ) 18 Non-compete agreements 140 (140 ) 0 140 (140 ) 0 Total $ 3,170 $ (1,864 ) $ 1,306 $ 3,170 $ (1,631 ) $ 1,539
Schedule of Expected Future Amortization Expense of Intangible Assets	As of June 30, 2017 , the expected future amortization expense for intangible assets was as follows (in thousands): Period Expected Future Amortization Expense 2017 233 2018 442 2019 351 2020 280 Total $ 1,306

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2017
Debt Disclosure [Abstract]
Schedule of Outstanding Debt	As of June 30, 2017 and December 31, 2016 , the Company’s outstanding debt is summarized as follows (in thousands): June 30, 2017 December 31, 2016 Promissory note to USAC — 120 FCC civil penalty 667 1,000 Total notes payable, gross 667 1,120 Less: discount (34 ) (79 ) Total notes payable, net carrying value 633 1,041 Revolving line of credit 32,594 32,594 Interest accretion under 2016 line of credit $ 30 $ 19 Total debt, net carrying value $ 33,257 $ 33,654 Less: current portion of debt * (663 ) (742 ) Total debt, less current portion ** 32,594 32,912 * Included in ‘Notes payable’ in the condensed consolidated balance sheets. ** Included in ‘Notes payable - less current portion’ and 'Revolving line of credit — less current portion' in the condensed consolidated balance sheets.
Schedule of Maturities of Debt	Maturities of the Company’s outstanding debt as of June 30, 2017 are as follows (in thousands): Period Amount to Mature 2017 333 2018 334 2019 32,594 Total $ 33,261

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2017
Equity [Abstract]
Schedule of Common Stock Reserved for Future Issuance	Shares of common stock reserved for future issuance related to outstanding equity awards, common stock warrants, and employee equity incentive plans were as follows (in thousands): June 30, 2017 Stock options outstanding 4,791 Restricted stock units outstanding 2,412 Shares available for future grant under 2014 Plan 7,590 Shares available for future issuance under ESPP 1,495 Common stock warrants outstanding 13 Total shares of common stock reserved 16,301
Schedule of Stock Option Activity	A summary of the Company’s stock option activity during the six months ended June 30, 2017 is as follows (in thousands, except years and per share data): Number of Weighted Weighted Aggregate Outstanding as of December 31, 2016 5,556 $ 5.23 Options granted (weighted average grant date fair value of $8.01 per share) 485 16.52 Options exercised (1,123 ) 2.05 Options forfeited or expired (127 ) 12.86 Outstanding as of June 30, 2017 4,791 $ 6.91 6.4 $ 70,014
Schedule of RSU Activity	A summary of the Company's restricted stock unit ("RSU") activity during the six months ended June 30, 2017 is as follows (in thousands, except per share data): Number of Shares Weighted Average Grant Date Fair Value Per Share Outstanding as of December 31, 2016 2,019 $ 7.65 RSUs granted 921 16.83 RSUs vested and released (422 ) 8.27 RSUs forfeited (106 ) 11.09 Outstanding as of June 30, 2017 2,412 $ 10.85
Schedule of Stock-based Compensation Expense	Stock-based compensation expenses for the three and six months ended June 30, 2017 and 2016 were as follows (in thousands): Three Months Ended Six Months Ended June 30, 2017 June 30, 2016 June 30, 2017 June 30, 2016 Cost of revenue $ 575 $ 329 $ 1,009 $ 594 Research and development 801 528 1,438 963 Sales and marketing 1,224 544 2,152 978 General and administrative 1,254 1,013 2,384 1,873 Total stock-based compensation $ 3,854 $ 2,414 $ 6,983 $ 4,408 As of June 30, 2017 , unrecognized stock-based compensation expenses by award type and their expected weighted-average recognition periods are summarized in the following table (in thousands, except years). Stock Option RSU ESPP Unrecognized stock-based compensation expense $ 7,196 $ 23,823 $ 570 Weighted-average amortization period 2.8 years 3.0 years 0.4 years
Schedule of Valuation Assumptions, Stock Option	The weighted-average assumptions used to value stock options granted during the three and six months ended June 30, 2017 and 2016 were as follows: Stock Options Three Months Ended Six Months Ended June 30, 2017 June 30, 2016 June 30, 2017 June 30, 2016 Expected term (years) 6.1 6.1 6.2 6.0 Volatility 49% 48% 49% 48% Risk-free interest rate 2.0% 1.2% 2.0% 1.5% Dividend yield — — — —

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Basic and Diluted Net Loss Per Share	The following table presents the calculation of basic and diluted net loss per share (in thousands, except per share data). Three Months Ended Six Months Ended June 30, 2017 June 30, 2016 June 30, 2017 June 30, 2016 Net loss $ (4,007 ) $ (3,468 ) $ (9,262 ) $ (8,379 ) Weighted-average shares used in computing basic and diluted net loss per share 54,723 52,143 54,208 51,760 Basic and diluted net loss per share $ (0.07 ) $ (0.07 ) $ (0.17 ) $ (0.16 )
Schedule of Antidilutive Securities Excluded from Computation of Net Loss Per Share	The following securities were excluded from the calculation of diluted net loss per share attributable to common stockholders because their effect would have been anti-dilutive for the periods presented (in thousands). June 30, 2017 June 30, 2016 Stock options 4,791 5,831 Restricted stock units 2,412 2,228 ESPP — 147 Common stock warrants 13 132 Total 7,216 8,338

Geographical Information (Table

Geographical Information (Tables)	6 Months Ended
	Jun. 30, 2017
Segment Reporting [Abstract]
Schedule of Revenues and Property and Equipment by Geographic Region	The following table is a summary of revenues by geographic region based on client billing address and has been estimated based on the amounts billed to clients during the periods presented (in thousands). Three Months Ended Six Months Ended June 30, 2017 June 30, 2016 June 30, 2017 June 30, 2016 United States $ 44,830 $ 36,104 $ 89,188 $ 71,697 International 2,897 2,782 5,553 5,204 Total revenue $ 47,727 $ 38,886 $ 94,741 $ 76,901 The following table summarizes total property and equipment, net in the respective locations (in thousands). June 30, 2017 December 31, 2016 United States $ 14,241 $ 13,025 International 1,415 1,663 Property and equipment, net $ 15,656 $ 14,688

Description of Business and S24

Description of Business and Summary of Significant Accounting Policies dsdd (Details) - ASU 2016-09 $ in Millions	Jan. 01, 2017USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred tax asset	$ 5.3
Deferred tax asset, valuation allowance	5.3
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effect on financial statements	$ 0.2

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Assets Carried at Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Money market funds
Assets
Cash equivalents	$ 20,038	$ 20,069
Money market funds | Level 1
Assets
Cash equivalents	20,038	20,069
Money market funds | Level 3
Assets
Cash equivalents	0	0
Embedded conversion option held for investment
Assets
Other Assets	917	873
Embedded conversion option held for investment | Level 1
Assets
Other Assets	0	0
Embedded conversion option held for investment | Level 3
Assets
Other Assets	$ 917	$ 873

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation of Unobservable Inputs (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 873
Total gains included in earnings	44
Ending balance	$ 917

Financial Statement Component27

Financial Statement Components - Schedule of Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Financial Statement Components [Abstract]
Cash	$ 37,111	$ 38,053
Money market funds	20,038	20,069
Cash and cash equivalents	$ 57,149	$ 58,122	$ 57,638	$ 58,484

Financial Statement Component28

Financial Statement Components - Schedule of Accounts Receivable (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Accounts Receivable [Line Items]
Allowance for doubtful accounts	$ (10)	$ (12)
Accounts receivable, net	16,281	13,881
Trade accounts receivable
Accounts Receivable [Line Items]
Trade accounts receivable	15,147	12,640
Unbilled trade accounts receivable, net of advance client deposits
Accounts Receivable [Line Items]
Trade accounts receivable	$ 1,144	$ 1,253

Financial Statement Component29

Financial Statement Components - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Financial Statement Components [Abstract]
Prepaid expenses	$ 3,326	$ 2,199
Other current assets	3,748	809
Prepaid expenses and other current assets	$ 7,074	$ 3,008

Financial Statement Component30

Financial Statement Components - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment
Property and equipment	$ 49,765	$ 45,026
Accumulated depreciation and amortization	(34,109)	(30,338)
Property and equipment, net	15,656	14,688
Computer and network equipment
Property, Plant and Equipment
Property and equipment	41,221	37,664
Computer software
Property, Plant and Equipment
Property and equipment	6,198	5,133
Internal-use software development costs
Property, Plant and Equipment
Property and equipment	500	475
Furniture and fixtures
Property, Plant and Equipment
Property and equipment	1,214	1,130
Leasehold improvements
Property, Plant and Equipment
Property and equipment	$ 632	$ 624

Financial Statement Component31

Financial Statement Components - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Financial Statement Components [Abstract]
Depreciation and amortization expense associated with property and equipment	$ 2.2	$ 1.9	$ 4.1	$ 3.9

Financial Statement Component32

Financial Statement Components - Schedule of Capital Leased Property and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Financial Statement Components [Abstract]
Gross	$ 41,346	$ 35,504
Less: accumulated depreciation and amortization	(28,338)	(23,128)
Total	$ 13,008	$ 12,376

Financial Statement Component33

Financial Statement Components - Schedule of Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Financial Statement Components [Abstract]
Accrued compensation and benefits	$ 8,608	$ 7,456
Accrued expenses	1,669	2,148
Accrued and other current liabilities	$ 10,277	$ 9,604

Intangible Assets - Schedule of

Intangible Assets - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Acquired Finite-Lived Intangible Assets
Gross Carrying Amount	$ 3,170	$ 3,170
Accumulated Amortization	(1,864)	(1,631)
Total	1,306	1,539
Developed technology
Acquired Finite-Lived Intangible Assets
Gross Carrying Amount	2,460	2,460
Accumulated Amortization	(1,302)	(1,126)
Total	1,158	1,334
Customer relationships
Acquired Finite-Lived Intangible Assets
Gross Carrying Amount	520	520
Accumulated Amortization	(385)	(333)
Total	135	187
Domain names
Acquired Finite-Lived Intangible Assets
Gross Carrying Amount	50	50
Accumulated Amortization	(37)	(32)
Total	13	18
Non-compete agreements
Acquired Finite-Lived Intangible Assets
Gross Carrying Amount	140	140
Accumulated Amortization	(140)	(140)
Total	$ 0	$ 0

Intangible Assets - Schedule 35

Intangible Assets - Schedule of Expected Future Amortization Expense of Intangible Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
2,017	$ 233
2,018	442
2,019	351
2,020	280
Total	$ 1,306	$ 1,539

Intangible Assets Intangible As

Intangible Assets Intangible Assets - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Amortization expense related to intangible assets	$ 0.1	$ 0.1	$ 0.2	$ 0.3

Debt - 2016 Loan and Security A

Debt - 2016 Loan and Security Agreement (Details) - USD ($)	Aug. 01, 2016	Sep. 30, 2016	Jun. 30, 2017	Dec. 31, 2016
Line of Credit Facility [Line Items]
Debt, gross			$ 33,261,000
Loan and Security Agreement 2016 | Revolving Credit Facility
Line of Credit Facility [Line Items]
Credit facility, maximum borrowing capacity	$ 50,000,000
Credit facility, amount outstanding	$ 32,600,000
Unused line of credit capacity fee	0.25%
First and second anniversary fee for line of credit	$ 31,250
Credit facility, remaining borrowing capacity			17,400,000
Payments of debt issuance costs	$ 200,000
Debt issuance costs, amortization period	3 years
Unrestricted cash required to be deposited with lenders	$ 25,000,000
Line of Credit
Line of Credit Facility [Line Items]
Debt, gross			$ 32,594,000	$ 32,594,000
Loan and Security Agreements 2014 and 2013
Line of Credit Facility [Line Items]
Loss on extinguishment of debt		$ 1,000,000
Prepayment penalties on extinguishment of debt		400,000
Write-off of unamortized debt discounts		400,000
Write-off of unamortized debt issuance costs		$ 200,000
Prime Rate | Loan and Security Agreement 2016 | Revolving Credit Facility
Line of Credit Facility [Line Items]
Debt instrument, basis spread	0.50%
Percentage increase in interest rate if adjusted EBITDA is negative at the end of the quarter	0.25%

Debt - 2013 Loan and Security A

Debt - 2013 Loan and Security Agreement (Details) - 2013 Loan and Security Agreement - USD ($) $ in Millions	1 Months Ended
	Oct. 31, 2013	Mar. 31, 2013
Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity		$ 20
Covenant terms, minimum required cash on deposit at lender		$ 7.5
Revolving Credit Facility | Prime Rate
Debt Instrument [Line Items]
Debt instrument, basis spread		0.50%
Term Loan
Debt Instrument [Line Items]
Credit facility, amount borrowed under agreement	$ 5
Term Loan | Prime Rate
Debt Instrument [Line Items]
Debt instrument, basis spread	1.50%

Debt - 2014 Loan and Security A

Debt - 2014 Loan and Security Agreement (Details)	1 Months Ended
	Feb. 28, 2014USD ($)lender$ / sharesshares	Jun. 30, 2017USD ($)
Debt Instrument [Line Items]
Debt, gross		$ 33,261,000
Term Loan | 2014 Loan and Security Agreement
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity	$ 30,000,000
Number of lenders | lender	2
Credit facility, remaining borrowing capacity	$ 10,000,000
Credit facility, minimum incremental borrowing amount	$ 1,000,000
Term Loan | 2014 Loan and Security Agreement | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Minimum variable rate on term loan	10.00%
Debt instrument, basis spread	9.00%
Term Loan | Tranche One
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity	$ 20,000,000
Payments of debt issuance costs	400,000
Debt, gross	$ 20,000,000
Common Stock | Term Loan | 2014 Loan and Security Agreement
Debt Instrument [Line Items]
Warrants issued | shares	177,865
Warrants outstanding, exercise price (in USD per share) | $ / shares	$ 10.12
Common Stock | Term Loan | Tranche One
Debt Instrument [Line Items]
Warrants vested, shares | shares	118,577
Warrants vested, fair value	$ 1,000,000
Common Stock Warrant | Term Loan | 2014 Loan and Security Agreement
Debt Instrument [Line Items]
Class of warrant or right, vesting period (in years)	10 years
Warrants unvested, shares | shares	59,288

Debt - Promissory Note_FCC Civi

Debt - Promissory Note/FCC Civil Penalty (Details) $ in Thousands	1 Months Ended
	Jun. 30, 2015USD ($)payment	Jul. 31, 2013USD ($)payment	Jun. 30, 2017USD ($)	Dec. 31, 2016USD ($)
Debt Instrument [Line Items]
Debt, gross			$ 33,261
Total debt, net carrying value			33,257	$ 33,654
Notes Payable
Debt Instrument [Line Items]
Debt, gross			667	1,120
Discount on debt			34	79
Total debt, net carrying value			633	1,041
Notes Payable | Promissory Note
Debt Instrument [Line Items]
Debt, gross		$ 4,100
Debt instrument, stated interest rate		12.75%
Debt instrument, number of monthly payments | payment		42
Notes Payable | FCC Civil Penalty
Debt Instrument [Line Items]
Debt, gross	$ 2,000		700	1,000
Debt instrument, stated interest rate	12.75%
Debt instrument, number of quarterly payments | payment	12
Discount on debt	$ 300
Total debt, net carrying value	$ 1,700		$ 600	$ 900

Debt - Schedule of Outstanding

Debt - Schedule of Outstanding Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2015
Debt Instrument [Line Items]
Debt, gross	$ 33,261
Total debt, net carrying value	33,257	$ 33,654
Less: current portion of debt	(663)	(742)
Total debt, less current portion	32,594	32,912
Notes Payable
Debt Instrument [Line Items]
Debt, gross	667	1,120
Less: discount	(34)	(79)
Total debt, net carrying value	633	1,041
Notes Payable | Promissory note to USAC
Debt Instrument [Line Items]
Debt, gross	0	120
Total debt, net carrying value		100
Notes Payable | FCC Civil Penalty
Debt Instrument [Line Items]
Debt, gross	700	1,000	$ 2,000
Less: discount			(300)
Total debt, net carrying value	600	900	$ 1,700
Line of Credit
Debt Instrument [Line Items]
Debt, gross	32,594	32,594
Long-term Debt, Interest Accretion	$ 30	$ 19

Debt - Schedule of Maturities o

Debt - Schedule of Maturities of Debt (Details) $ in Thousands	Jun. 30, 2017USD ($)
Debt Disclosure [Abstract]
2,017	$ 333
2,018	334
2,019	32,594
Total	$ 33,261

Stockholders' Equity - Capital

Stockholders' Equity - Capital Structure (Details) - $ / shares	Jun. 30, 2017	Dec. 31, 2016
Equity [Abstract]
Common Stock, shares authorized (in shares)	450,000,000	450,000,000
Common Stock, par value (in USD per share)	$ 0.001	$ 0.001
Common Stock, shares issued (in shares)	55,095,711	53,363,013
Common Stock, shares outstanding (in shares)	55,095,711	53,363,013
Preferred Stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred Stock, par value (in USD per share)	$ 0.001	$ 0.001
Preferred Stock, shares issued (in shares)	0	0
Preferred Stock, shares outstanding (in shares)	0	0

Stockholders' Equity - Warrants

Stockholders' Equity - Warrants (Details) - $ / shares	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Class of Warrant or Right
Warrant expiration date	2023-10
Common Stock
Class of Warrant or Right
Warrants outstanding (in shares)	13,017	131,597
Outstanding warrants exercise price, weighted-average (in USD per share)	$ 6.93	$ 9.80

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock Reserved for Future Issuance (Details) - shares	Jun. 30, 2017	Dec. 31, 2016	Apr. 03, 2014
Class of Stock
Common stock reserved for future issuance (in shares)	16,301,000
Stock options
Class of Stock
Stock options outstanding (in shares)	4,791,000	5,556,000
Restricted stock units
Class of Stock
Restricted stock units outstanding (in shares)	2,412,000	2,019,000
ESPP
Class of Stock
Common stock reserved for future issuance (in shares)	1,494,632		880,000
Common stock warrants outstanding
Class of Stock
Common stock reserved for future issuance (in shares)	13,000
2014 Plan
Class of Stock
Shares available for future grant (in shares)	7,590,000

Stockholders' Equity - Equity I

Stockholders' Equity - Equity Incentive Plans (Details) - 2014 Plan - shares	Jun. 30, 2017	Jan. 01, 2017	Jan. 01, 2016	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award
Automatic annual increase in common stock reserved for issuance, percentage				5.00%
Automatic annual increase in common stock reserved for issuance, shares		2,668,150	2,558,231
Number of shares available for future grant	7,590,000
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award
Number of shares originally authorized for issuance				5,300,000
Number of shares available for future grant	7,589,526

Stockholders' Equity - Stock Op

Stockholders' Equity - Stock Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2017USD ($)$ / sharesshares
Class of Stock
Closing market price of common stock (in USD per share)	$ 21.52
Stock options
Options Outstanding [Roll Forward]
Outstanding, beginning balance (in shares) | shares	5,556
Options granted (weighted average grant date fair value of $3.81 per share) (in shares) | shares	485
Options exercised (in shares) | shares	(1,123)
Options forfeited or expired (in shares) | shares	(127)
Outstanding, ending balance (in shares) | shares	4,791
Options Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, beginning balance, weighted average exercise price (in USD per share)	$ 5.23
Options granted, weighted average exercise price (in USD per share)	16.52
Options exercised, weighted average exercise price (in USD per share)	2.05
Options forfeited or expired, weighted average exercise price (in USD per share)	12.86
Outstanding, ending balance, weighted average exercise price (in USD per share)	6.91
Weighted average grant date fair value, options granted (in USD per share)	$ 8.01
Outstanding, ending balance, weighted average remaining contractual life	6 years 4 months 24 days
Outstanding, ending balance, aggregate intrinsic value | $	$ 70,014

Stockholders' Equity - RSU Acti

Stockholders' Equity - RSU Activity (Details) - Restricted stock units shares in Thousands	6 Months Ended
	Jun. 30, 2017$ / sharesshares
Number of Shares
Outstanding, beginning balance (in shares) | shares	2,019
RSUs granted (in shares) | shares	921
RSUs vested and released (in shares) | shares	(422)
RSUs forfeited (in shares) | shares	(106)
Outstanding, ending balance (in shares) | shares	2,412
Weighted Average Grant Date Fair Value Per Share
Outstanding, beginning balance, weighted-average grant date fair value per share (in USD per share) | $ / shares	$ 7.65
RSUs granted, weighted average grant date fair value (in USD per share) | $ / shares	16.83
RSUs vested and released, weighted average grant date fair value (in USD per share) | $ / shares	8.27
RSUs forfeited, weighted average grant date fair value (in USD per share) | $ / shares	11.09
Outstanding, ending balance, weighted-average grant date fair value per share (in USD per share) | $ / shares	$ 10.85

Stockholders' Equity - ESPP (De

Stockholders' Equity - ESPP (Details) - $ / shares	May 15, 2017	Jun. 30, 2017	Jan. 01, 2017	May 13, 2016	Jan. 01, 2016	Apr. 03, 2014
Share-based Compensation Arrangement by Share-based Payment Award
Common stock reserved for future issuance (in shares)		16,301,000
ESPP
Share-based Compensation Arrangement by Share-based Payment Award
Common stock reserved for future issuance (in shares)		1,494,632				880,000
Automatic annual increase in common stock reserved for issuance, percentage						1.00%
Maximum annual increase of shares reserved						1,000,000
Automatic annual increase in common stock reserved for issuance, shares			533,630		511,646
Purchases made under the ESPP	141,222
Weighted average purchase price (in USD per share)				$ 12.75

Stockholders' Equity - Stock-ba

Stockholders' Equity - Stock-based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Stock-based Compensation Expense
Stock-based compensation expense	$ 3,854	$ 2,414	$ 6,983	$ 4,408
Cost of revenue
Stock-based Compensation Expense
Stock-based compensation expense	575	329	1,009	594
Research and development
Stock-based Compensation Expense
Stock-based compensation expense	801	528	1,438	963
Sales and marketing
Stock-based Compensation Expense
Stock-based compensation expense	1,224	544	2,152	978
General and administrative
Stock-based Compensation Expense
Stock-based compensation expense	1,254	$ 1,013	2,384	$ 1,873
Stock options
Stock-based Compensation Expense
Unrecognized stock-based compensation expense	7,196		$ 7,196
Weighted-average amortization period			2 years 9 months 24 days
Restricted stock units
Stock-based Compensation Expense
Unrecognized stock-based compensation expense	23,823		$ 23,823
Weighted-average amortization period			3 years 18 days
ESPP
Stock-based Compensation Expense
Unrecognized stock-based compensation expense	$ 570		$ 570
Weighted-average amortization period			4 months 16 days

Stockholders' Equity - Valuatio

Stockholders' Equity - Valuation Assumptions (Details) - Stock options	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Class of Stock
Expected term (years)	6 years 29 days	6 years 1 month 6 days	6 years 2 months 12 days	6 years
Volatility	49.00%	48.00%	49.00%	48.00%
Risk-free interest rate	2.00%	1.20%	2.00%	1.50%
Dividend yield	0.00%	0.00%	0.00%	0.00%

Net Loss Per Share - Basic and

Net Loss Per Share - Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Net loss	$ (4,007)	$ (3,468)	$ (9,262)	$ (8,379)
Weighted-average shares used in computing basic and diluted net loss per share (in shares)	54,723	52,143	54,208	51,760
Basic and diluted net loss per share (in USD per share)	$ (0.07)	$ (0.07)	$ (0.17)	$ (0.16)

Net Loss Per Share - Antidiluti

Net Loss Per Share - Antidilutive Securities Excluded from Computation of Diluted Net Loss Per Share (Details) - shares shares in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share
Anti-dilutive securities excluded from calculation of diluted net loss per share	7,216	8,338
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share
Anti-dilutive securities excluded from calculation of diluted net loss per share	4,791	5,831
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share
Anti-dilutive securities excluded from calculation of diluted net loss per share	2,412	2,228
ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share
Anti-dilutive securities excluded from calculation of diluted net loss per share	0	147
Common stock warrants | Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share
Anti-dilutive securities excluded from calculation of diluted net loss per share	13	132

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Provision for (benefit from) income taxes	$ 50	$ 42	$ 99	$ 70

Commitments and Contingencies -

Commitments and Contingencies - Commitments (Details) $ in Millions	6 Months Ended
	Jun. 30, 2017USD ($)
Capital lease obligations
Other Commitments [Line Items]
Capital lease future payment obligations incurred	$ 4.7
Capital lease future minimum payments, remainder of 2017	0.9
Capital lease future minimum payments, due after 2017	$ 3.8
Period remainder of minimum payments is due	31 months
Hosting and telecommunications agreement
Other Commitments [Line Items]
Various agreements total minimum future payment commitments	$ 4.1
Minimum | Hosting and telecommunications agreement
Other Commitments [Line Items]
Period for various agreements	24 months
Maximum | Hosting and telecommunications agreement
Other Commitments [Line Items]
Period for various agreements	36 months

Commitments and Contingencies56

Commitments and Contingencies - Universal Services Fund Liability (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		6 Months Ended
	Jan. 31, 2017	Jul. 31, 2013	Jun. 30, 2017	Dec. 31, 2012	Jun. 30, 2017	Dec. 31, 2016	Jun. 12, 2015
Loss Contingencies [Line Items]
Accrued federal fees			$ 3,261		$ 3,261	$ 2,742
Debt, gross			33,261		33,261
Long-term Debt			33,257		33,257	33,654
FCC Enforcement Bureau Civil Penalty
Loss Contingencies [Line Items]
Accrued liability							$ 2,000
2003 through 2012 | USF obligations
Loss Contingencies [Line Items]
Accrued federal fees				$ 8,100
2003 through 2012 | Undisputed portion | USF obligations
Loss Contingencies [Line Items]
Accrued federal fees				4,700
Payments		$ 600
2003 through 2012 | Disputed portion | USF obligations
Loss Contingencies [Line Items]
Accrued federal fees				3,400
2008 through 2012 | Disputed portion | USF obligations
Loss Contingencies [Line Items]
Accrued federal fees				3,900
Increase (decrease) in accrual federal fees	$ 3,100			$ (500)
2003 through 2007 | Disputed portion | USF obligations
Loss Contingencies [Line Items]
Accrued federal fees			2,800		2,800	2,500
Increase (decrease) in accrual federal fees	$ 3,100
Interest and penalty expense			200		300
2003 through 2007 | Disputed portion | USF Obligations - Assessment
Loss Contingencies [Line Items]
Accrued federal fees			800		800	800
2003 through 2007 | Disputed portion | USF Obligations - Interest and Penalties on Assessment
Loss Contingencies [Line Items]
Accrued federal fees			400		400	300
2003 through 2007 | Disputed portion | USF Obligations - Interest and Penalties on Prior Payments
Loss Contingencies [Line Items]
Accrued federal fees			$ 1,600		$ 1,600	1,400
Promissory Note | USF obligations
Loss Contingencies [Line Items]
Debt, gross		$ 4,100
Notes Payable | Promissory Note | USF obligations
Loss Contingencies [Line Items]
Long-term Debt						$ 100

Commitments and Contingencies57

Commitments and Contingencies - State and Local Taxes and Surcharges (Details) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2015	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Loss Contingencies [Line Items]
General and administrative	$ 6,845,000	$ 5,882,000		$ 15,705,000	$ 12,418,000
Sales tax liability	1,284,000			1,284,000		$ 1,476,000
Accrued sales tax liability, current	1,191,000			1,191,000		1,347,000
Contingent sales tax liabilities
Loss Contingencies [Line Items]
Payments	0	25,000
Sales tax liability	1,800,000			1,800,000		2,100,000
Accrued sales tax liability, current	500,000			$ 500,000		$ 600,000
Out of Period Adjustment | Contingent sales tax liabilities
Loss Contingencies [Line Items]
General and administrative			$ 600,000
General and administrative expense | Contingent sales tax liabilities
Loss Contingencies [Line Items]
Estimated sales tax liability gain	$ 100,000	$ 200,000

Commitments and Contingencies58

Commitments and Contingencies - Legal Matters (Details) $ in Thousands	Jun. 30, 2017USD ($)
Indemnification Agreement
Loss Contingencies [Line Items]
Estimate of possible loss	$ 62

Geographical Information - Sche

Geographical Information - Schedule of Revenue and Property and Equipment by Geographic Region (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets
Revenue	$ 47,727	$ 38,886	$ 94,741	$ 76,901
Property and equipment, net	15,656		15,656		$ 14,688
United States
Revenues from External Customers and Long-Lived Assets
Revenue	44,830	36,104	89,188	71,697
Property and equipment, net	14,241		14,241		13,025
International
Revenues from External Customers and Long-Lived Assets
Revenue	2,897	$ 2,782	5,553	$ 5,204
Property and equipment, net	$ 1,415		$ 1,415		$ 1,663