ShotSpotter (SSTI) 10-K 4 Mar 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 28, 2019	Jun. 29, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Trading Symbol	SSTI
Entity Registrant Name	ShotSpotter, Inc.
Entity Central Index Key	1,351,636
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Well Known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		10,911,848
Entity Public Float			$ 270,329,955

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 10,218	$ 19,567
Accounts receivable and unbilled revenue	15,267	3,928
Prepaid expenses and other current assets	1,527	839
Restricted cash	60	30
Total current assets	27,072	24,364
Property and equipment, net	16,504	11,596
Goodwill	1,379
Intangible assets, net	242	95
Other assets	1,922	143
Total assets	47,119	36,198
Current liabilities
Accounts payable	1,307	1,627
Deferred revenue, short-term	23,102	15,780
Accrued expenses and other current liabilities	4,427	3,815
Total current liabilities	28,836	21,222
Deferred revenue, long-term	1,060	2,710
Other liabilities	76	104
Total liabilities	29,972	24,036
Commitments and contingencies (Note 17)
Stockholders' equity
Preferred stock: $0.005 par value; 20,000,000 shares authorized; no shares issued and outstanding as of December 31, 2018 and 2017
Common stock: $0.005 par value; 500,000,000 shares authorized; 10,864,722 and 9,827,129 shares issued and outstanding as of December 31, 2018 and 2017, respectively	55	48
Additional paid-in capital	114,618	109,708
Accumulated deficit	(97,377)	(97,595)
Accumulated other comprehensive income (loss)	(149)	1
Total stockholders' equity	17,147	12,162
Total liabilities and stockholders' equity	$ 47,119	$ 36,198

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.005	$ 0.005
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.005	$ 0.005
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	10,864,722	9,827,129
Common stock, shares outstanding	10,864,722	9,827,129

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Revenues	$ 34,753	$ 23,763	$ 15,507
Costs
Cost of revenues	14,846	11,370	9,549
Impairment of property and equipment	686	793
Total costs	15,532	12,163	9,549
Gross profit	19,221	11,600	5,958
Operating expenses
Sales and marketing	8,377	6,179	4,475
Research and development	4,987	4,159	4,093
General and administrative	8,425	5,595	2,362
Total operating expenses	21,789	15,933	10,930
Operating loss	(2,568)	(4,333)	(4,972)
Other income (expense), net
Remeasurement of convertible preferred stock warrant liability		(3,725)	(524)
Loss on early extinguishment of debt		(479)
Interest income (expense), net	82	(1,114)	(1,317)
Other expense, net	(252)	(169)	(47)
Total other income (expense), net	(170)	(5,487)	(1,888)
Loss before income taxes	(2,738)	(9,820)	(6,860)
Provision (benefit) for income taxes	(13)	160
Net loss	$ (2,725)	$ (9,980)	$ (6,860)
Net loss per share, basic and diluted	$ (0.26)	$ (1.61)	$ (4.28)
Weighted average shares used in computing net loss per share, basic and diluted	10,569,007	6,197,775	1,602,402

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (2,725)	$ (9,980)	$ (6,860)
Other comprehensive income (loss):
Change in foreign currency translation adjustment	(150)	3	(2)
Comprehensive loss	$ (2,875)	$ (9,977)	$ (6,862)

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity/(Deficit) - USD ($)	Total	Series B-1 Convertible Preferred Stock	Series A-2 Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Beginning balance at Dec. 31, 2015	$ (50,452,000)			$ 8,000	$ 30,295,000	$ (80,755,000)
Temporary equity, Beginning balance, Shares at Dec. 31, 2015		3,848,023	1,176,423
Temporary equity, Beginning balance at Dec. 31, 2015		$ 22,075,000	$ 20,000,000
Beginning balance, Shares at Dec. 31, 2015				1,583,601
Exercise of stock options	25,000				25,000
Exercise of stock options, Shares				33,395
Stock-based compensation	83,000				83,000
Other comprehensive (loss) income	(2,000)						$ (2,000)
Net loss	(6,860,000)					(6,860,000)
Ending balance at Dec. 31, 2016	(57,206,000)			$ 8,000	30,403,000	(87,615,000)	(2,000)
Temporary equity, Ending balance, Shares at Dec. 31, 2016		3,848,023	1,176,423
Temporary equity, Ending balance at Dec. 31, 2016		$ 22,075,000	$ 20,000,000
Ending balance, Shares at Dec. 31, 2016				1,616,996
Issuance of common stock upon IPO, net $3.0 million in commissions and discounts	32,426,000			$ 16,000	32,410,000
Issuance of common stock upon IPO, Shares				3,220,000
IPO costs	(1,870,000)				(1,870,000)
Conversion of convertible preferred stock of common stock upon IPO	42,075,000			$ 23,000	42,052,000
Temporary equity conversion of convertible preferred stock of common stock upon IPO, Shares		(3,848,023)	(1,176,423)
Temporary equity conversion of convertible preferred stock of common stock upon IPO		$ (22,075,000)	$ (20,000,000)
Conversion of convertible preferred stock of common stock upon IPO, Shares				4,689,753
Reclassification of preferred stock warrant liability into additional paid in capital upon IPO	5,711,000				5,711,000
Exercise of stock options	55,000				55,000
Exercise of stock options, Shares				74,984
Issuance of common stock in connection with cashless exercise of warrants	1,000			$ 1,000
Issuance of common stock in connection with cashless exercise of warrants, Shares				191,263
Issuance of common stock from ESPP purchase	319,000				319,000
Issuance of common stock from ESPP purchase, Shares				34,133
Stock-based compensation	628,000				628,000
Other comprehensive (loss) income	3,000						3,000
Net loss	(9,980,000)					(9,980,000)
Ending balance at Dec. 31, 2017	12,162,000			$ 48,000	109,708,000	(97,595,000)	1,000
Ending balance, Shares at Dec. 31, 2017				9,827,129
Exercise of stock options	550,000			$ 3,000	547,000
Exercise of stock options, Shares				609,985
Issuance of common stock in connection with exercise of warrants	988,000			$ 1,000	987,000
Issuance of common stock in connection with exercise of warrants, shares				296,691
Issuance of common stock from ESPP purchase	909,000				909,000
Issuance of common stock from ESPP purchase, Shares				83,605
Issuance of common stock from RSU's vested	2,000			$ 3,000	(1,000)
Issuance of common stock from RSU's vested, shares				47,312
Stock-based compensation	2,468,000				2,468,000
Other comprehensive (loss) income	(150,000)						(150,000)
Cumulative effect of change in accounting principle	2,943,000					2,943,000
Net loss	(2,725,000)					(2,725,000)
Ending balance at Dec. 31, 2018	$ 17,147,000			$ 55,000	$ 114,618,000	$ (97,377,000)	$ (149,000)
Ending balance, Shares at Dec. 31, 2018				10,864,722

Consolidated Statements of Co_2

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity/(Deficit) (Parenthetical) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Statement Of Stockholders Equity [Abstract]
Underwriting commissions and discounts	$ 3

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net loss	$ (2,725,000)	$ (9,980,000)	$ (6,860,000)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	3,917,000	3,121,000	2,551,000
Impairment of property and equipment	686,000	793,000
Stock-based compensation	2,468,000	628,000	83,000
Amortization of debt issuance costs		132,000	131,000
Remeasurement of convertible preferred stock warrant liability		3,725,000	524,000
Loss on early extinguishment of debt		479,000
Loss on disposal of property and equipment	4,000		27,000
Changes in operating assets and liabilities:
Accounts receivable	(11,224,000)	(1,518,000)	255,000
Prepaid expenses and other assets	(766,000)	(247,000)	(90,000)
Accounts payable	(346,000)	291,000	410,000
Accrued expenses and other current liabilities	(246,000)	1,535,000	1,049,000
Deferred revenue	6,846,000	4,428,000	4,177,000
Net cash provided by (used in) operating activities	(1,386,000)	3,387,000	2,257,000
Cash flows from investing activities:
Purchase of property and equipment	(8,444,000)	(6,430,000)	(4,476,000)
Investment in intangible and other assets	(48,000)	(76,000)	(78,000)
Business acquisition	(1,711,000)
Net cash used in investing activities	(10,203,000)	(6,506,000)	(4,554,000)
Cash flows from financing activities:
Proceeds from initial public offering, net of commissions and discounts		32,426,000
Proceeds from notes payable		1,500,000	2,000,000
Repayment of notes payable		(13,500,000)
Payment of debt issuance costs		(30,000)	(17,000)
Payment on debt extinguishment costs		(149,000)
Payments of initial public offering costs		(1,870,000)
Proceeds from exercise of stock options	550,000	55,000	25,000
Proceeds from exercise of warrants	988,000
Proceeds from employee stock purchase plan	909,000	319,000
Net cash provided by financing activities	2,437,000	18,751,000	2,008,000
Increase (decrease) in cash, cash equivalents and restricted cash	(9,152,000)	15,632,000	(289,000)
Effect of exchange rate on cash and cash equivalents	(167,000)	70,000	30,000
Cash, cash equivalents and restricted cash at beginning of year	19,597,000	3,895,000	4,154,000
Cash, cash equivalents and restricted cash at end of period	10,278,000	19,597,000	3,895,000
Supplemental cash flow disclosures:
Cash paid for interest		1,235,000	$ 1,186,000
Supplemental disclosure of non-cash financing activities:
Estimated fair value of contingent consideration	750,000
Conversion of convertible preferred stock into common stock		42,075,000
Reclassification of convertible preferred stock warrant liability into additional paid-in capital		5,711,000
Deferred offering costs included in other assets	249,000
Issuance of warrants in connection with the issuance of notes payable		$ 111,000
Line of Credit
Cash flows from financing activities:
Payment of debt issuance costs	(10,000)
Supplemental disclosure of non-cash financing activities:
Deferred offering costs included in other assets	$ 91,000

Organization and Description of

Organization and Description of Business	12 Months Ended
	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Description of Business	Note 1. Organization and Description of Business ShotSpotter, Inc. (the “Company”) provides precision-policing solutions for law enforcement to help deter gun violence and make cities, campuses and facilities safer. The company’s flagship product, ShotSpotter Flex, is the leading outdoor gunshot detection, location and forensic system trusted by more than 95 cities. ShotSpotter Missions (formerly HunchLab) uses artificial intelligence-driven analysis to help strategically plan patrol missions and tactics for maximum crime deterrence. The Company offers its solutions on a SaaS-based subscription model to its customers. The Company’s principal executive offices are located in Newark, California. The Company has one subsidiary, ShotSpotter (Pty) Ltd. formed in South Africa.

Initial Public Offering

Initial Public Offering	12 Months Ended
	Dec. 31, 2018
Initial Public Offering [Abstract]
Initial Public Offering	Note 2. Initial Public Offering In June 2017, the Company completed its initial public offering (“IPO”) in which the Company sold 3,220,000 shares of its common stock at a price of $11.00 per share. The Company received net proceeds of $32.4 million, excluding underwriting discounts and commissions, which was recorded to additional paid-in capital. The Company’s common stock commenced trading on the Nasdaq Capital Market on June 7, 2017 under the trading symbol “SSTI.” • Immediately prior to the IPO, all outstanding Series B-1 convertible preferred stock warrants were remeasured at fair value using the Black-Scholes model, resulting in a loss of $3.7 million, which was recorded in other expense, net. • Upon the closing of the IPO, the entire balance of $5.7 million in convertible preferred stock warrant liability was reclassified to additional paid-in capital. All preferred stock warrants were converted into common stock warrants. In addition, the Company issued to the lead underwriter in the IPO a warrant to purchase up to 84,000 shares of its common stock. See Note 14, Convertible Preferred Stock Warrants and Common Stock Warrants , for further details regarding the warrants. • Upon the closing of the IPO, all shares of the then-outstanding convertible preferred stock were converted into 4,689,753 shares of common stock. This resulted in a reclassification of $42.1 million to additional paid-in capital. • Offering costs incurred by the Company were approximately $1.9 million, excluding underwriting commissions and discounts, which was recorded to additional paid-in capital.

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Note 3. Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding financial reporting. The consolidated financial statements include the results of the Company and its wholly-owned subsidiary, ShotSpotter (Pty) Ltd. All significant intercompany transactions have been eliminated during consolidation. In the opinion of management, the accompanying consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the financial position, results of operations, comprehensive loss, equity statement and cash flows for the full year 2018. June 2017 Amended and Restated Certificate of Incorporation Prior to the IPO, the Company’s Board of Directors (the “Board”) and stockholders approved an amendment (the “Charter Amendment”) to the Pre-IPO Certificate (as defined below) and an amended and restated certificate of incorporation (“Post-IPO Certificate”) that became effective on June 12, 2017. The Charter Amendment increased the number of authorized shares of common stock from 8,600,000 to 500,000,000. Under the Post-IPO Certificate, the Company is authorized to issue two classes of stock to be designated Common Stock and Preferred Stock. See Note 11, Capital Stock March 2017 Amendment and Restatement of Certificate of Incorporation On March 27, 2017, the Company’s Board and stockholders approved an amendment and restatement of the Company’s then-existing certificate of incorporation (as so amended and restated, the “Pre-IPO Certificate”) to provide, among other changes, that each share of Series A-2 convertible preferred stock would automatically convert into 0.715548 shares of common stock upon the consummation of an initial public offering of the Company’s capital stock. All share and per share data related to balance sheet and net loss information in the accompanying consolidated financial statements and their related notes have been retroactively adjusted to give effect to the application of this conversion feature when presenting the Series A-2 convertible preferred stock on an as-converted basis. The Pre-IPO Certificate also provided for (1) an increase in the total number of authorized shares to 14,550,000 and (2) an increase in the number of authorized shares of common stock to 8,600,000, in each case to accommodate the new conversion feature for the outstanding shares of Series A-2 convertible preferred stock. Reverse Stock Split and Amendment to Certificate of Incorporation In December 2016, the Board and stockholders approved an amendment and restatement of the Company’s then amended and restated certificate of incorporation to effect a one-for-17 reverse stock split of the outstanding shares of the Company’s capital stock, such that each 17 shares of capital stock issued and outstanding, automatically and without any action on the part of the respective holders thereof, combined into one share of the same class and series of capital stock. All share and per share data in the accompanying consolidated financial statements and their related notes for all periods presented have been retroactively adjusted to give effect to the reverse stock split. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and reported amounts of revenues and expenses during the reporting period. On an ongoing basis, management evaluates its significant estimates including the valuation of accounts receivable, the useful lives of tangible and intangible assets, fair values of intangible assets and goodwill, stock-based compensation expense, preferred stock warrant liabilities, and accounting for income taxes. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions it believes to be reasonable under the circumstances. Actual results could differ from those estimates and such differences could be material to the Company’s financial position and results of operations. Revenue Recognition The Company generates substantially all of its revenues from the sale of gunshot detection subscription services, in which gunshot data generated by Company-owned sensors and software is sold to customers through a cloud-based hosting application for a specified contract period. Typically, the initial contract period is one to five years in length. The subscription contract is generally noncancelable without cause. Generally, these service arrangements do not provide the customer with the right to take possession of the hardware or software supporting the subscription service at any time. A small portion of the Company’s revenues are generated from the delivery of setup services to install Company-owned sensors in the customer’s coverage area and other services including training and license to integrate with third-party applications. The Company generally invoices customers for 50% of the total contract value when the contract is fully executed and for the remaining 50% when the subscription service is operational and ready to go live – that is, when the customer has acknowledged the completion of all the deliverables in the signed customer acceptance form. The Company generally invoices subscription service renewals for 100% of the total contract value when the renewal contract is executed. For the public safety solution, the pricing model is based on a per-square-mile basis. For security solutions, the pricing model is on a customized-site basis. As a result of the process for invoicing contracts and renewals upon execution, cash flows from operations and accounts receivable can fluctuate due to timing of contract execution and timing of deployment. Prior to the adoption of Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606), Revenue Recognition • Persuasive evidence of an arrangement exists; • Delivery has occurred or services have been rendered; • The sales price is fixed or determinable; and • Collection of the related receivable is reasonably assured. Under ASC 605, the Company recognized subscription revenues ratably over the subscription period committed by the customer and commencing when the subscription service was fully operational and ready to go live, that is, upon completion of all deliverables stated in the signed customer acceptance form, assuming all other revenue recognition criteria were met. The Company recognized revenues from setup fees ratably based on the expected customer relationship period, typically over five years, which could extend beyond the initial contract period. In determining the expected customer relationship period, the Company considered specific customer details and renewal history with similar customers. If a customer declined to renew its subscription prior to the end of five years, then the remaining setup fees were immediately recognized. Effective January 1, 2018, after the adoption of Topic 606, the Company recognizes revenue upon the satisfaction of performance obligations. At contract inception, the Company assesses the services promised in its contracts with customers and identifies a performance obligation for each promise to transfer to the customer a good or service (or bundle of services) that is distinct. To identify the performance obligations, the Company considers all of the services promised in the contract regardless of whether they are explicitly stated or are implied by customary business practices. The Company determined that the subscription services, training, and licenses to integrate with third-party applications are each distinct services that represent separate performance obligations. The setup activities are not distinct from the subscription service and are combined into the subscription service performance obligation. However, setup fees may provide a material right to the customer that has influence over the customers' decision to renew. All setup fees are assessed on a quantitative and qualitative basis to determine whether they represent a distinct performance obligation. The total contract value is allocated to each performance obligation identified based on the standalone selling price of the service. Discounts are allocated pro-rata to the identified performance obligations. For contracts that have an original duration of one year or less, the Company uses the practical expedient applicable to such contracts and does not consider the time value of money. Revenues from subscription services are recognized ratably, on a straight-line basis, over the term of the subscription. Revenues from material rights are recognized ratably over the period in which they are determined to provide a material right to the customer, which is generally three years. Revenues from training and licenses to integrate with third-party applications are recognized upon delivery which generally occurs when the subscription service is operational and ready to go live and these amounts are immaterial. Subscription renewal fees are recognized ratably over the term of the renewal, which is typically one year. While most customers elect to renew their agreements, in some cases, they may not be able to obtain the proper approvals or funding to complete the renewal prior to expiration. For these customers, the Company stops recognizing subscription revenues at the end of the current contract term, even though services may continue to be provided for a period of time until the renewal process is completed. Once the renewal is complete, the Company recognizes subscription revenues for the period between the expiration of the term of the agreement and the completion of the renewal process in the month in which the renewal is executed. If a customer declines to renew its subscription prior to the end of three years, then the remaining fees from material rights, if any, are immediately recognized. As of January 1, 2018, upon the adoption of Topic 606, the Company had total short-term and long-term deferred revenue of $17.3 million. During the year ended December 31, 2018, the Company recognized $9.7 million in revenue from the beginning deferred revenue and $24.8 million from new billings, and added $41.4 million to total short-term and long-term deferred revenue from new billings. As of December 31, 2018, the Company has estimated remaining performance obligations for contractually committed revenues of $29.3 million, $20.9 million, $14.3 million, and $700,000 that will be recognized during the years ended December 31, 2019, 2020, 2021, and 2022 through 2024, respectively. The timing of revenue recognition includes estimates of go live dates for contracts not yet live. Contractually committed revenue includes deferred revenue as of December 31, 2018 and amounts under contract that will be invoiced after December 31, 2018. During the year ended December 31, 2018, the Company recognized revenues of $33.9 million from customers in the United States and $0.9 million from a customer in South Africa. Topic 606 also requires the capitalization of certain incremental costs of obtaining a contract, which impacts the period in which the Company records sales commissions expense. Historically, the Company recognized sales commissions expense upfront. Under Topic 606, the Company is required to capitalize these expenses. As there are not commensurate commissions earned on renewals of the subscription services, the Company concluded that the capitalized commissions are related to subscription services provided under both the initial contract and renewal periods. Therefore, the amortization period for the capitalized commissions is the customer life, which is determined to be five years. As the capitalized commissions are related to subscription services that are transferred over the customer's life, the Company amortizes the capitalized commissions on a straight-line basis of five years. For commissions that are earned on renewal contracts with an original duration of one year or less, the Company uses the practical expedient applicable to such commissions and recognizes the commissions immediately as expense instead of capitalizing. Amortization of capitalized commissions was $0.5 million for the year ended December 31, 2018 and was included in sales and marketing expense in the consolidated statements of operations. Costs Costs include the cost of revenues and charges for impairment of property and equipment. Cost of revenues primarily includes depreciation expense associated with capitalized customer acoustic sensor networks, communication expenses, costs related to hosting our service application, costs related to operating our Incident Review Center (the “IRC”), providing remote and on-site customer support and maintenance and forensic services, certain personnel and related costs of operations, stock-based compensation and allocated overhead, which includes information technology, facility and equipment depreciation costs. Advertising and Promotion Costs Advertising and promotion costs are expensed as incurred. Advertising and promotion costs were $0.6 million for the year ended December 31, 2018 and $0.5 million for each of the years ended December 31, 2017 and 2016, and were included in sales and marketing expense in the consolidated statements of operations. Research and Development Costs Research and development costs are expensed as incurred and consisted primarily of salaries and benefits, consultant fees, certain facilities costs, and other direct costs associated with the continued development of the Company’s solutions. Cash and Cash Equivalents Cash and cash equivalents include all cash and highly liquid investments with an original maturity of three months or less. At December 31, 2018 and 2017, the Company’s cash and cash equivalents consisted of cash deposited in financial institutions. Restricted Cash At December 31, 2018 and 2017, restricted cash consisted of certificates of deposit held at a financial institution as collateral for credit cards and letters of credit held by the Company. Foreign Currency The functional currency for the Company’s foreign subsidiary, ShotSpotter (Pty) Ltd., is the local currency (South African Rand). The assets and liabilities of the subsidiary are translated into U.S. dollars using the exchange rate at the end of each balance sheet date. Revenues and expenses are translated at the average exchange rates for the period. Gains and losses from translations are recognized in foreign currency translation included in accumulated other comprehensive loss in the accompanying consolidated balance sheets. Foreign currency exchange gains and losses are recorded in other expense, net, in the accompanying consolidated statements of operations. Accounts Receivable, net and Unbilled Revenue Accounts receivable, net consist of trade accounts receivables from the Company’s customers, net of allowance for doubtful accounts if deemed necessary. Accounts receivable are recorded as the invoiced amount. The Company does not require collateral or other security for accounts receivable. Unbilled revenue consists of revenue recognized in advance of invoicing the customer. The Company periodically evaluates the collectability of its accounts receivable and provides an allowance for potential credit losses based on the Company’s historical experience. At December 31, 2018 and 2017, the Company did not have an allowance for potential credit losses as there were no estimated credit losses. Concentrations of Risk Credit Risk Financial instruments that potentially subject the Company to concentration of credit risk consisted primarily of restricted cash, cash and cash equivalents and accounts receivable from trade customers. The Company maintains its cash deposits at three domestic and one international financial institutions. The Company is exposed to credit risk in the event of default by a financial institution to the extent that cash and cash equivalents are in excess of the amount insured by the Federal Deposit Insurance Corporation. The Company generally places its cash and cash equivalents with high-credit quality financial institutions. To date, the Company has not experienced any losses on its cash and cash equivalents. Concentration of Accounts Receivable At December 31, 2018, one customer accounted for 77%, of the Company’s account receivable. Fluctuations in accounts receivable result from timing of the Company’s execution of contracts and collection of related payments. At December 31, 2017, three customers accounted for 18%, 18% and 14% of the Company’s accounts receivable. Concentration of Revenues For the year ended December 31, 2018, two customers accounted for 22% and 15% of the Company’s revenues. For the year ended December 31, 2017, one customer accounted for 18% of the Company’s revenue. For the year ended December 31, 2016, two customers each accounted for 12% of the Company’s revenues. Concentration of Suppliers The Company relies on a limited number of suppliers and contract manufacturers. In particular, a single supplier is currently the sole manufacturer of the Company’s proprietary sensors. Business Acquisitions The Company allocates the fair value of purchase consideration to the tangible assets acquired, liabilities assumed and intangible assets acquired based on their estimated fair values. The excess of the fair value of purchase consideration over the fair values of these identifiable assets and liabilities is recorded as goodwill. When determining the fair values of assets acquired and liabilities assumed, management makes significant estimates and assumptions, especially with respect to intangible assets. Acquisition-related expenses are recognized separately from the business combination and are recognized as general and administrative expense as incurred. Goodwill Following the acquisition of HunchLab (see Note 7, Business Acquisitions Intangible Assets Intangible assets consisted of acquired patents and capitalized legal fees related to obtaining patents, as well as customer relationships as a result from the Company’s acquisition of HunchLab in 2018 (see Note 7, Business Acquisitions Property and Equipment, net Property and equipment, net, is stated at cost, less accumulated depreciation and amortization. The Company depreciates property and equipment using the straight-line method over their estimated useful lives, ranging from three to five years. Leasehold improvements are amortized over the shorter of the asset’s useful life or the remaining lease term. Accounting for Impairment of Long-Lived Assets The Company annually reviews long-lived assets for impairment or whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparing the carrying amount of the asset to the future undiscounted net cash flows which the asset is expected to generate. If such assets are determined to be impaired, the impairment to be recognized is measured as the amount by which the carrying amount of the assets exceeds the future undiscounted net cash flows arising from the assets. Assets to be disposed of are reported at the lower of their carrying amounts or fair value less cost to sell. During the year ended December 31, 2018, the Company recognized impairment expense of $0.7 million for the impairment of property and equipment primarily related to the remaining book value of indoor sensor inventory and indoor sensor networks installed at certain security customers. During the year ended December 31, 2017, the Company recognized impairment expense of $0.8 million for the impairment of property and equipment primarily related to the remaining net book value for deployed equipment that was presumed destroyed by hurricanes in September 2017. The Company did not record any impairment of long-lived assets during the year ended December 31, 2016. Royalty Expense In 2009, the Company entered into a license agreement with a third party relating to a patented gunshot digital imaging system that facilitates integration with certain third-party systems. The terms of the license agreement require the Company to pay a one-time fee of $5,000 for each license sold to a customer allowing the customer to integrate their ShotSpotter service with a third-party application, such as a video management system, with a minimum annual amount due of $75,000. In 2018, 2017, and 2016, the Company incurred only the $75,000 minimum amount. The license agreement renews automatically on each subsequent year unless it is terminated in accordance with the agreement. The royalty fee due for each license sold to a customer is capitalized as property and equipment and amortized over the estimated useful life. The difference in royalty fees capitalized in property and equipment and the minimum annual payment is classified as general and administrative expense in the consolidated statements of operations and was $35,000, $60,000 and $35,000 for the years ended December 31, 2018, 2017, and 2016, respectively. Convertible Preferred Stock Warrants The Company issued warrants exercisable for shares of Series B-1 convertible preferred stock, or for shares of common stock upon the automatic conversion of all outstanding series of preferred stock into common stock. These warrants were classified as a preferred stock warrant liability in the consolidated balance sheets, rather than stockholders’ equity, as they met the criteria to be classified as a derivative liability. The convertible preferred stock warrants were subject to remeasurement to fair value at each balance sheet date and any change in fair value is recognized as a component of other expense, net, in the consolidated statements of operations. The Company estimates the fair value of the warrants using an option pricing method (“OPM”) or probability weighed expected return method (“PWERM”) that incorporates the use of OPM, to allocate the estimated value of the Company. The OPM treats classes of stock as call options on a company’s enterprise value with exercise prices based on the liquidation preferences of convertible preferred stock. The OPM prices the call option using the Black-Scholes model. The PWERM relies on a forward-looking analysis to predict the possible future value of a company by weighing discrete future outcomes. Upon the closing of the IPO in 2017, the convertible preferred stock warrant liability was reclassified to additional paid-in capital. All preferred stock warrants were converted into common stock warrants. Fair Value Measurements The Company uses a three-level hierarchy for fair value measurements based on the nature of inputs used in the valuation of an asset or liability as of the measurement date. The three-level hierarchy prioritizes, within the measurement of fair value, the use of market-based information over entity-specific information. Fair value focuses on an exit price and is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The inputs or methodology used for valuing financial instruments are not necessarily an indication of the risks associated with investing in those financial instruments. The three-level hierarchy for fair value measurements is defined as follows: Level I — Inputs to the valuation methodology are quoted prices (unadjusted) for identical assets or liabilities in active markets. Level II — Inputs to the valuation methodology include quoted prices for similar assets and liabilities in active markets, and inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the financial instrument. Level III — Inputs to the valuation methodology are unobservable and significant to the fair value measurement. An asset’s or a liability’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. Stock-Based Compensation The Company generally grants options to purchase shares of its common stock to its employees and directors for a fixed number of shares with an exercise price equal to the fair value of the underlying shares at the grant date. Fair value is determined by the Board. The Company accounts for these options under ASC Topic 718, Compensation—Stock Compensation. Accordingly, all stock option grants are accounted for using the fair value method, and stock-based compensation expense is recognized as the underlying options vest. The Company uses the Black-Scholes option pricing model to measure the fair value of its stock options. Stock-based compensation for options granted to non-employees is measured on the date of performance at the fair value of the consideration received or the fair value of the equity instruments issued, whichever is more reliably measured. Compensation for options granted to non-employees is periodically remeasured as the underlying options vest. Prior to the IPO, given the absence of a public trading market for the Company’s common stock, the Board considered numerous objective and subjective factors to determine the fair value of the Company’s common stock each time stock option grants were approved. The factors include, but are not limited to: (i) the valuation of the Company’s common stock by an unrelated third party; (ii) the Company’s results of operations, financial position and capital resources; (iii) current economic indicators and outlook; (iv) competition for the Company’s solutions; and (v) the Company’s marketing methods. The Company estimated the grant date fair value of its common stock options using the following assumptions: Expected Term — The expected term represents the period that the stock-based compensation awards are expected to be outstanding. Since the Company did not have sufficient historical information to develop reasonable expectations about future exercise behavior, the Company used the simplified method to compute expected term, which reflects the weighted-average of time-to-vesting. Risk-Free Interest Rate — The risk-free interest rate is based on the yield on U.S. Treasury yield curve in effect at the grant date. Expected Volatility — Since the Company does not have a long trading history of its common stock, the expected volatility is derived from the average historical volatilities of publicly traded companies that are reasonably comparable to the Company’s own operations. Dividend Yield — After the IPO, the Company uses the market closing price of its common stock as traded on the Nasdaq Capital Market to determine fair value. The Company generally grants unvested restricted stock unit awards to non-employee directors for a fixed number of shares and a fixed vesting date. The restricted stock unit awards are valued using the closing price on the date of grant. Forfeitures are recognized as and when they occur. Segment Information The Company has one operating segment with one business activity, providing gunshot detection systems. The Company’s chief operating decision maker is its Chief Executive Officer, who manages operations on a consolidated basis for purposes of allocating resources. Income Taxes The Company records income taxes in accordance with the liability method of accounting. Deferred taxes are recognized for the estimated taxes ultimately payable or recoverable based on enacted tax law. The Company establishes a valuation allowance to reduce the deferred tax assets when it is more likely than not that a deferred tax asset will not be realizable. Changes in tax rates are reflected in the tax provision as they occur. In accounting for uncertainty in income taxes, the Company recognizes the financial statement benefit of a tax position only after determining that the relevant tax authority would more likely than not sustain the position following an audit. For tax positions meeting the more likely than not threshold, the amount recognized in the consolidated financial statements is the largest benefit that has a greater than 50 percent likelihood of being realized upon ultimate settlement with the relevant tax authority. Net Loss per Share Attributable to Common Stockholders Basic net loss per share is calculated by dividing net loss by the weighted-average number of common shares outstanding during the period. Diluted net loss per share is computed by dividing net loss by the weighted-average number of common shares and common stock equivalents outstanding during the period. Common stock equivalents are only included when their effect is dilutive. Common stock equivalents and unvested restricted stock units are potentially dilutive securities and include convertible preferred stock, warrants and outstanding stock options. These potentially dilutive securities are excluded from the computation of diluted net loss per share if their inclusion would be anti-dilutive. For all periods presented, there is no difference in the number of shares used to compute basic and dilutive shares outstanding due to the Company’s net loss position. Accounting Pronouncements Recently Adopted Effective January 1, 2018, the Company adopted Topic 606. The impact from the adoption of Topic 606 was as follows: Year Ended December 31, 2018 As Reported Effect of Change Increase/ (Decrease) Amounts Without Adoption of Topic 606 Revenues $ 34,753 $ 392 $ 34,361 Costs $ 15,532 $ — $ 15,532 Gross profit $ 19,221 $ 392 $ 18,829 Sales and marketing expense $ 8,377 $ (438 ) $ 8,815 Operating loss $ (2,568 ) $ (830 ) $ (3,398 ) Net loss $ (2,725 ) $ (830 ) $ (3,555 ) As of December 31, 2018 As Reported Effect of Change Increase/ (Decrease) Amounts Without Adoption of Topic 606 Assets Prepaid expenses and other current assets $ 1,527 $ 629 $ 898 Other assets $ 1,922 $ 1,560 $ 362 Total assets $ 47,119 $ 2,189 $ 44,930 Liabilities Deferred revenue, short term $ 23,102 $ 1,043 $ 22,059 Accrued expenses and other current liabilities $ 4,427 $ 82 $ 4,345 Total current liabilities $ 28,836 $ 1,125 $ 27,711 Deferred revenue, long term $ 1,060 $ (913 ) $ 1,973 Total liabilities $ 29,972 $ 212 $ 29,760 In January 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230) Classification of Certain Cash Receipts and Cash Payments In October 2016, the FASB issued ASU 2016-16, Intra-Entity Transfers of Assets Other Than Inventory In November 2016, the FASB issued ASU 2016-18, Restricted Cash In May 2017, the FASB issued ASU 2017-09, Scope of Modification Accounting Compensation – Stock Compensation Recent Accounting Pronouncements Not Yet Effective In February 2016, the FASB issued ASU 2016-02, Leases At transition, lessees and lessors may elect to apply a package of practical expedients permitting entities not to reassess: (i) whether any expired or existing contracts are or contain leases; (ii) lease classification for any expired or existing leases and (iii) whether initial direct costs for any expired or existing leases qualify for capitalization under the amended guidance. These practical expedients must be elected as a package and consistently applied. The Company has elected to apply the package of practical expedients upon adoption. The Company identified its operating lease for its corporate headquarters office impacted by the new standard and is currently in the process of updating its business processes and related policies, systems and controls to support recognition and disclosure under the new standard. Upon adoption of the amended guidance, the Company expects to recognize right-of-use assets and related lease liabilities of approximately $0.8 million for its contracts which contain an operating lease. The Company currently does not expect the amended guidance to have any other material impacts on our consolidated financial statements. In July 2017, the FASB issued ASU 2017-11 , Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), Derivatives and Hedging (Topic 815).

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 4. Fair Value Measurements Prior to the IPO, the Company’s convertible preferred stock warrant liability was measured on a recurring basis and was classified within Level III of the fair value hierarchy because some of the inputs used in its measurement were neither directly or indirectly observable. The valuation methodology and underlying assumptions in the fair value determination are discussed in Note 3, Basis of Presentation and Summary of Significant Accounting Policies Convertible Preferred Stock Warrants and Common Stock Warrants Immediately prior to the IPO, the convertible preferred stock warrant liability was remeasured to fair value, resulting in a loss of $3.7 million which was recorded in other expense, net. Upon the closing of the IPO, the entire balance of $5.7 million in convertible preferred stock warrant liability was reclassified to additional paid-in capital. There were no transfers into or out of Level III during the year ended December 31, 2018. The changes in the fair value of the convertible preferred stock warrant liability and changes in the fair value of contingent consideration are summarized below (in thousands): Fair Value Measurements at Reporting Date Using Level III Inputs Fair value at December 31, 2015 $ 1,351 Change in fair value recorded in other expense, net 524 Fair value at December 31, 2016 $ 1,875 Issuance of convertible preferred stock warrants 111 Change in fair value recorded in other expense, net 3,725 Reclassification of unexercised warrant into additional paid-in capital upon the IPO (5,711 ) Fair value at December 31, 2017 $ — Contingent consideration 750 Fair value at December 31, 2018 $ 750 As of the acquisition date of HunchLab (see Note 7, Business Acquisitions

Intangible Assets, Net

Intangible Assets, Net	12 Months Ended
	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible Assets, Net	Note 5. Intangible Assets, net Intangible assets, net, consisted of the following (in thousands): December 31, 2018 Gross Accumulated Amortization Net Patents $ 997 $ (909 ) $ 88 Customer relationship 160 (6 ) 154 $ 1,157 $ (915 ) $ 242 December 31, 2017 Gross Accumulated Amortization Net Patents $ 949 $ (854 ) $ 95 Amortization expense during the years ended December 31, 2018, 2017 and 2016 was $61,000, $47,000 and $37,000, respectively.

Details of Certain Consolidated

Details of Certain Consolidated Balance Sheet Accounts	12 Months Ended
	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Details of Certain Consolidated Balance Sheet Accounts	Note 6. Details of Certain Consolidated Balance Sheet Accounts Prepaid expenses and other current assets (in thousands): December 31, 2018 2017 Prepaid software and licenses $ 388 $ 407 Prepaid insurance 275 211 Other prepaid expenses 169 137 Deferred commissions 629 — Other 66 84 $ 1,527 $ 839 Other assets (in thousands): December 31, 2018 2017 Deferred commissions $ 1,560 $ — Other 362 143 $ 1,922 $ 143 Property and equipment, net (in thousands): December 31, 2018 2017 Deployed equipment $ 24,767 $ 17,091 Computer equipment 1,272 1,123 Software 1,239 312 Furniture and fixtures 210 165 Leasehold improvements 234 202 Construction in progress 953 1,456 $ 28,675 $ 20,349 Accumulated depreciation and amortization (12,171 ) (8,753 ) $ 16,504 $ 11,596 Accrued expenses and other current liabilities (in thousands): December 31, 2018 2017 Payroll liabilities $ 1,859 $ 1,697 Accrued employee paid time off 558 469 Accrued commissions 43 199 Accrued ESPP 143 115 Royalties payable 130 125 Professional fees 396 328 Sales/ use tax payable 273 406 Contingent consideration 750 — Other 275 476 $ 4,427 $ 3,815

Business Acquisitions

Business Acquisitions	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Business Acquisitions	Note 7. Business Acquisitions On October 3, 2018, the Company acquired certain technology, referred to as HunchLab, and related assets from Azavea Inc., a Philadelphia-based technology company. The purchase consideration totaled $2.5 million, consisting of $1.7 million in cash and a contingent earnout payable in cash for up to $750,000 based on HunchLab’s revenues generated over the three-year period following the acquisition date. The Company determined the acquisition-date fair value of the contingent consideration liability based on the likelihood of meeting revenue forecasts. The following table presents the purchase price allocation (in thousands): Accounts receivable $ 114 Prepaid expense 4 Deferred revenue, short term (120 ) Accounts payable (26 ) Software technology 950 Customer relationships 160 Goodwill 1,379 Total purchase consideration $ 2,461 Goodwill primarily represents the value of cash flows from future customers. The Company expects to deduct goodwill and identifiable technology and intangible assets for tax purposes, a portion of which will commence upon settlement of contingent consideration and contingent liabilities. The following table presents the components of the identifiable technology and intangible assets and the estimated useful lives (in thousands): Fair Value Useful Life Software technology $ 950 5 years Customer relationships 160 7 years Total identifiable technology and intangible assets $ 1,110 The Company valued customer relationships and the software technology using the income approach. Significant assumptions include forecasts of revenues, cost of revenue, research and development expense, sales and marketing expense, general and administrative expense and estimated customer attrition rates. The Company discounted the cash flows at 25.5%, reflecting the risk profile of the assets. Acquisition-related expenses totaled $0.2 million, which are included in general and administrative expense. The Company has not presented separate results of operations since closing or combined pro forma financial information of the Company and HunchLab since the beginning of fiscal 2017, as results of operations for HunchLab are immaterial.

Impairment of Property and Equi

Impairment of Property and Equipment	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Impairment of Property and Equipment	Note 8. Impairment of Property and Equipment During the year ended December 31, 2018, the Company recognized impairment expense of $0.7 million for the impairment of property and equipment primarily related to the remaining book value of indoor sensor inventory and indoor sensor networks installed at certain security customers. Management concluded that the impairment charges were required because the Company have made the strategic decision to no longer include indoor coverage as part of its service offering. During the year ended December 31, 2017, the Company recognized impairment expense of $0.8 million for the impairment of property and equipment primarily relating to the remaining net book value of deployed equipment in Puerto Rico and the U.S. Virgin Islands. Management concluded that the impairment charges were required because the equipment was presumed destroyed by the hurricanes in September 2017. During the year ended December 31, 2017, the Company also recognized $0.9 million in revenues relating to the remaining deferred set-up fees to be recognized primarily on contracts with customers in Puerto Rico and the U.S. Virgin Islands. Management concluded that the revenues associated with these contracts was required to be accelerated because the contracts with customers in Puerto Rico and the U.S. Virgin Islands were expired at the time of the hurricanes and all subscription services were fully delivered.

Financing Arrangements

Financing Arrangements	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Financing Arrangements	Note 9. Financing Arrangements Credit Agreement On September 27, 2018, the Company entered into a Credit Agreement with Umpqua Bank (the “Umpqua Credit Agreement”), which allows the Company to borrow up to $10.0 million under a revolving loan facility (the “Revolving Facility”). The Company intends to use the Revolving Facility for general working capital purposes. Borrowings under the Umpqua Credit Agreement are secured by substantially all of the assets of the Company. The Umpqua Credit Agreement includes a letter of credit subfacility of up to $3.0 million. Any amounts outstanding under the letter of credit subfacility reduce the amount available for the Company to borrow under the Revolving Facility. Borrowings under the Umpqua Credit Agreement bear interest, at the Company’s option, at a rate equal to either (1) a base rate, which fluctuates daily and is the greater of (a) the prime rate in effect as of any date of determination and (b) the daily LIBOR rate as of such date of determination plus 1.0% per annum, or (2) a LIBOR rate, which can be for a period of 30, 60 or 90 days at the Company’s option and is equal to the published rate in the Wall Street Journal for such 30-, 60- or 90-day period two business days prior to the commencement of such period, in each case plus 2.0% per annum. The Company will be required to repay all amounts outstanding under the Umpqua Credit Agreement on September 27, 2020 or earlier if the Umpqua Credit Agreement is terminated prior to such date. The Umpqua Credit Agreement also includes an uncommitted incremental facility provision that would allow the Company, subject to satisfaction of certain conditions, including approval by Umpqua Bank, to increase the Revolving Facility up to a total of $25.0 million. Under the Umpqua Credit Agreement, the Company is subject to various negative covenants that limit, subject to certain exclusions, the Company’s ability to incur indebtedness, make loans, invest in or secure the obligations of other parties, pay or declare dividends, make distributions with respect to the Company’s securities, redeem outstanding shares of the Company’s stock, create subsidiaries, materially change the nature of its business, enter into related party transactions, engage in mergers and business combinations, the acquisition or transfer of Company assets outside of the ordinary course of business, grant liens or enter into collateral relationships involving company assets or reincorporate, reorganize or dissolve the Company. There were no borrowings outstanding as of December 31, 2018. Notes Payable- 2015 Term Note Borrowings under the 2015 Term Note bore interest at the greater of: (i) the average prime rate in effect during each month or (ii) the average three-month LIBOR rate during such month, plus 2.5% per annum, plus 7.5% with a minimum rate of 11%, with interest only payments through October 2017, followed by 36 equal monthly installments of principal and interest through October 2020, the maturity date. The weighted average interest rate during the year ended December 31, 2017 was and 11.54%. For the year ended December 31, 2017 and 2016, the Company recognized interest expense of $1.1 million and $1.2 million, respectively, based on the outstanding balance during the period. During the year ended December 31, 2017 and 2016, amortization of debt issuance costs was $132,000 and $131,000, respectively. Amortization of debt issuance costs is recorded in interest expense in the consolidated statements of operations. Borrowings under the 2015 Term Note were secured by substantially all of the assets of the Company. Additionally, the terms of the 2015 Term Note included certain financial covenants and various negative covenants. In March 2017, the Company amended the 2015 Term Note. In connection with the amendment of the 2015 Term Note, the Company issued a warrant to purchase 76,704 shares of Series B-1 preferred stock at an exercise price of $5.8667 per share; however, the terms of the warrant provided that upon the completion of a public offering in which the Company raises at least $25.0 million in net proceeds, the number of shares underlying the warrant would be reduced to 61,363 shares. Consistent with these terms, upon the closing of the IPO, the number of shares underlying this warrant was reduced to 61,363 shares, and the warrant became exercisable for common stock. In September 2017, the Company voluntarily repaid all outstanding borrowings under the 2015 Term Note. The Company recorded to other expense, net, a loss of $0.2 million, consisting of prepayment fees and miscellaneous fees, and wrote-off $0.3 million of unamortized debt issuance costs from the early extinguishment of debt.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Note 10. Related Party Transactions During the year ended December 31, 2018, the Company did not have any related party transactions. During the years ended December 31, 2017 and 2016, the Company recognized approximately $700,000, and $200,000 in revenue, respectively, from a reseller who was also an investor. As of December 31, 2017, and 2016, the amount of accounts receivable due from this reseller was immaterial.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Text Block [Abstract]
Income Taxes	Note 11. Income Taxes The domestic and foreign components of net loss were as follows (in thousands): Year Ended December 31, 2018 2017 2016 Domestic $ (3,083 ) $ (10,125 ) $ (6,744 ) Foreign 345 305 (116 ) Net loss $ (2,738 ) $ (9,820 ) $ (6,860 ) The provision for income tax consists of the following (in thousands): Year Ended December 31, ​ 2018 2017 2016 Current: Federal $ — $ — $ — State — — — Foreign (13 ) 160 — Total (13 ) 160 — Deferred: Federal — — — State — — — Foreign — — — Total — — — Total tax expense $ (13 ) $ 160 $ — A reconciliation of income taxes at the statutory federal income tax rate to net income taxes included in the accompanying consolidated statements of operations is as follows (in thousands): December 31, 2018 2017 2016 Income tax at statutory rate $ (575 ) $ (3,339 ) $ (2,331 ) Change in valuation allowance 1,595 (8,354 ) 2,146 Change in tax rate — 9,788 — Change in deferreds 7 (39 ) — State tax (309 ) 536 9 Mark-to-market on warrants — 1,267 178 Stock-based compensation (615 ) 84 24 Research and development credit (220 ) (62 ) (88 ) Foreign rate differential (86 ) 56 40 Subpart F - transition tax 81 68 — Lobbying 78 79 — Other 31 76 22 Total $ (13 ) $ 160 $ — Temporary differences that gave rise to significant portions of the Company’s deferred tax assets and liabilities as of December 31, 2018 and 2017 were as follows (in thousands): Year Ended December 31, 2018 2017 Deferred tax assets: Net operating losses $ 21,461 $ 20,139 Credits 1,969 1,654 Accruals and reserves 285 643 Deferred revenue and contract costs 458 464 Gross deferred tax assets 24,173 22,900 Valuation allowance (23,710 ) (22,789 ) Net deferred tax assets 463 111 Deferred tax liabilities: Fixed assets and intangibles (545 ) (111 ) Total deferred tax liabilities, net $ (82 ) $ — Realization of deferred tax assets is dependent upon future taxable income, if any, the timing and amount of which are uncertain. Management has determined that the deferred tax assets are not realizable on a more likely than not basis. Accordingly, deferred tax assets have been fully offset by a valuation allowance. The valuation allowance increased by $0.9 million during the year ended December 31, 2018. As of December 31, 2018, we had federal net operating loss carryforwards of approximately $85.4 million, of which $80.6 million will expire between 2026 through 2037, if not utilized, and $4.8 million which do not expire. As of December 31, 2018, we also had state NOLs of approximately $54.3 million, which will expire, if not utilized, in 2019 through 2038. As of December 31, 2018, the Company had available for carryover research and experimental credits for federal and California income tax purposes of approximately $1.5 million and $1.5 million, respectively, which are available to reduce future income taxes. The federal research and experimental tax credits will begin to expire, if not utilized, in 2026. The California research and experimental tax credits carry forward indefinitely until utilized. Section 382 of the Internal Revenue Code of 1986 (the “Code”), as amended, and similar California regulations impose substantial restrictions on the utilization of net operating losses and tax credits in the event of an “ownership change” of a corporation. Accordingly, the Company’s ability to utilize net operating losses and credit carryforwards may be limited as the result of such an “ownership change” as defined in the Code. Uncertain Tax Positions The Company applied FASB ASC 740-10-50, Accounting for Uncertainty in Income Tax, The Company had unrecognized tax benefits of approximately $0.7 million as of December 31, 2018, all of which was offset by a full valuation allowance. No interest or penalties have been accrued as of December 31, 2018. A reconciliation of the beginning and ending amounts of unrecognized tax benefits is as follows (in thousands): Balance as of December 31, 2016 $ 574 Increases for current year tax positions 46 Increases for prior year tax positions — Balance as of December 31, 2017 620 Increases for current year tax positions 114 Increases for prior year tax positions — Balance as of December 31, 2018 $ 734 Unrecognized tax benefits may change during the next 12 months for items that arise in the ordinary course of business. The Company does not anticipate a material change to its unrecognized tax benefits over the next 12 months that would affect the Company’s effective tax rate. The Company files income tax returns in federal, various state and U.S. territory jurisdictions, and South Africa. The statute of limitations remains open for fiscal years 2005 through 2017 in the United States and the various state and the U.S. territory jurisdictions. Years beyond the normal statute of limitations remain open to audit by tax authorities due to tax attributes generated in earlier years which are being carried forward and may be audited in subsequent years when utilized. On December 22, 2017, the 2017 Tax Cut and Jobs Act (the Act) was enacted into law and the new legislation contains several key tax provisions, including a one-time mandatory transition tax on accumulated foreign earnings and a reduction of the corporate income tax rate to 21% effective January 1, 2018, among others. We are required to recognize the effect of the tax law changes in the period of enactment, such as determining the estimated transition tax, re-measuring our U.S. deferred tax assets and liabilities at a 21% rate as well as reassessing the net realizability of our deferred tax assets and liabilities. The one-time transition tax does not generate a tax liability as the deemed distribution is offset by tax attributes. The provisional amount related to the re-measurement of our deferred tax balance is a reduction of approximately $9.8 million. Due to the corresponding valuation allowance fully offsetting deferred taxes, there is no income statement impact. In December 2017, the SEC staff issued Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act (SAB 118) which allows companies to record provisional amounts during a measurement period not to extend beyond one year of the enactment date. Since the Tax Act was passed late in the fourth quarter of 2017, and ongoing guidance and accounting interpretation was yet to be issued, our accounting of the deferred tax re-measurements were incomplete as of December 31, 2017. The 2017 Federal corporate income tax return was filed in fourth quarter of 2018. The final analysis and impact of the Act is reflected in the tax provision and related tax disclosures for the year ended December 31, 2018. There were no material differences to the originally estimated $9.8 million remeasurement of deferred tax assets. In January 2018, the FASB released guidance on the accounting for tax on the global intangible low-taxed income ("GILTI") provisions of the Act. The GILTI provisions impose a tax on foreign income in excess of a deemed return on tangible assets of foreign corporations. The guidance indicates that either accounting for deferred taxes related to GILTI inclusions or treating any taxes on GILTI inclusions as period cost are both acceptable methods subject to an accounting policy election. For the year ended December 31, 2018, the Company has elected to treat any potential GILTI inclusions as a period cost.

Capital Stock

Capital Stock	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Capital Stock	Note 12. Capital Stock Convertible Preferred Stock Immediately prior to the IPO, the Company had the following outstanding convertible preferred stock: Shares Authorized Shares Issued and Outstanding Aggregate Liquidation Preference (in thousands) Series B-1 4,773,000 3,848,023 $ 22,575 Series A-2 1,177,000 1,176,423 20,000 $ 42,575 Upon the closing of the IPO, all shares of convertible preferred stock then outstanding were automatically converted into an aggregate of 4,689,753 shares of common stock, resulting in the reclassification of the related redeemable convertible preferred stock into $23,000 of common stock and $42.1 million into additional paid-in capital. As of December 31, 2018, there were no shares of convertible preferred stock outstanding. Common Stock The Company is authorized to issue 500,000,000 shares of common stock with a par value of $0.005 per share. At December 31, 2018 and 2017, there were 10,864,722 and 9,827,129 shares of common stock issued and outstanding, respectively. Holders of common stock have voting rights equal to one vote per share of common stock held and are entitled to receive any dividends as may be declared from time to time by the Board. Prior to the IPO, common stock was subordinate to Series B-1 convertible preferred stock with respect to dividend rights and subordinate to Series B-1 and A-2 convertible preferred stock with respect to rights upon certain deemed liquidation events of the Company. At December 31, 2018, shares of common stock reserved for future issuance were as follows: December 31, 2018 Options outstanding 820,186 Shares available for future grant 1,248,424 Unvested restricted stock units 110,764 Warrants to purchase common stock 163,713 Total 2,343,087 Preferred Stock The Company is authorized to issue 20,000,000 shares of preferred stock, with a par value of $0.005, as provided in the Post-IPO Certificate. As of December 31, 2018, there were no shares of preferred stock issued and outstanding.

Net Loss per Share

Net Loss per Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Net Loss per Share	Note 13. Net Loss per Share The following table summarizes the computation of basic and diluted net loss per share (in thousands, except share and per share data): Year Ended December 31, 2018 2017 2016 Numerator: Net loss $ (2,725 ) $ (9,980 ) $ (6,860 ) Denominator: Weighted-average shares outstanding, basic and diluted 10,569,007 6,197,775 1,602,402 Net loss per share $ (0.26 ) $ (1.61 ) $ (4.28 ) The following potentially dilutive shares outstanding at the end of the periods presented were excluded in the calculation of diluted net loss per share as the effect would have been anti-dilutive: Year Ended December 31, 2018 2017 2016 Options to purchase common stock 820,186 1,294,128 1,130,141 Unvested restricted stock units 110,764 47,312 — Warrants to purchase Series B-1 convertible preferred or common stock 163,713 468,278 680,027 Series B-1 convertible preferred stock (as-converted) — — 3,848,023 Series A-2 convertible preferred stock (as-converted) — — 841,730 Total 1,094,663 1,809,718 6,499,921

Convertible Preferred Stock War

Convertible Preferred Stock Warrants and Common Stock Warrants	12 Months Ended
	Dec. 31, 2018
Warrants And Rights Note Disclosure [Abstract]
Convertible Preferred Stock Warrants and Common Stock Warrants	Note 14. Convertible Preferred Stock Warrants and Common Stock Warrants Immediately prior to the Company’s IPO, all outstanding Series B-1 convertible preferred stock warrants were remeasured to their fair value, using the Black-Scholes model. Refer to Note 3, Basis of Presentation and Summary of Significant Accounting Policie Upon the closing of the IPO, the entire balance of $5.7 million in convertible preferred stock warrant liability was reclassified to additional paid-in capital. All convertible preferred stock warrants were converted into common stock warrants. In addition, the Company issued to the lead underwriter in the IPO a warrant to purchase up to 84,000 shares of its common stock. During the year ended December 31, 2018, certain warrants were exercised on a cashless basis and converted into 25,145 shares of common stock. At December 31, 2016, the Company had the following Series B-1 convertible preferred stock warrants issued and outstanding (in thousands, except share and per share data): Warrant Class Shares Fair Value Issuance Date Price per Share Expiration Date Series B-1 25,568 $ 303 June 2012 $ 5.8667 June 2022 Series B-1 167,428 $ 263 July 2012 $ 5.8667 July 2019 Series B-1 145,801 $ 46 August 2012 $ 5.8667 August 2019 Series B-1 10,517 $ 19 November 2012 $ 5.8667 November 2022 Series B-1 156,851 $ 929 February 2014 $ 0.1700 February 2021 Series B-1 173,862 $ 315 September 2015 $ 5.8667 September 2025 Total 680,027 $ 1,875 At December 31, 2018 and 2017, the Company had the following common stock warrants issued and outstanding: Shares Warrant Class 2018 2017 Issuance Date Price per Share Expiration Date Common stock warrant 3,766 165,925 July 2012 $ 5.8667 July 2019 Common stock warrant 25,231 61,502 August 2012 $ 5.8667 August 2019 Common stock warrant 50,716 156,851 February 2014 $ 0.1700 February 2021 Common stock warrant (1) 84,000 84,000 June 2017 $ 13.2000 June 2020 163,713 468,278 (1 ) This warrant was issued to the Company’s lead underwriter in connection with the IPO. In March 28, 2017, in connection with the amendment of the 2015 Term Note (see Note 9 , Financing Arrangements In June 2017, in connection with its public offering, the Company issued a warrant to purchase 84,000 shares of common stock to its lead underwriter (the “June 2017 Warrant”). The Company determined the fair value of the June 2017 Warrant on the date of issuance to be $0.3 million. The June 2017 Warrant was immediately exercisable.

Equity Incentive Plans

Equity Incentive Plans	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Equity Incentive Plans	Note 15. Equity Incentive Plans 2017 Equity Incentive Plan In May 2017, the Board and the Company’s stockholders approved the 2017 Equity Incentive Plan (the “2017 Plan”), which became effective in connection with the IPO. The 2017 Plan provides for the issuance of stock options, restricted stock units and other awards to employees, directors and consultants of the Company. A total of 2,413,659 shares of the Company’s common stock were initially reserved for issuance under the 2017 Plan, which is the sum of (1) 900,000 shares, (2) the number of shares reserved for issuance under the 2005 Plan at the time the 2017 Plan became effective and (3) shares subject to stock options or other stock awards under the 2005 Plan that would have otherwise been returned to the 2005 Plan (up to a maximum of 1,314,752 shares). The number of shares of common stock reserved for issuance under the 2017 Plan will automatically increase on January 1 of each year, beginning on January 1, 2018 by the lesser of (1) 5% of the number of shares of the Company’s capital stock outstanding on December 31 st Incentive Stock Options may only be granted to Company employees and may only be granted with an exercise price not less than the fair value of the common stock, or not less than 110% of fair value when the grant is issued to a person who, at the time of grant, owns stock representing more than 10% of the voting power of all classes of stock. Non-statutory stock options may be granted to Company employees, directors and consultants, and may be granted at a price per share not less than fair value on the date of the grant. The Board determines the fair value of the Company’s common stock. Options granted under the 2005 Plan and 2017 Plan generally vest over four years and expire no later than 10 years from the grant date. The 2005 Plan and 2017 Plan grants the Board discretion to determine when the options granted will become exercisable. The 2005 Plan and 2017 Plan allows for the exercise of unvested options with repurchase rights over the restricted common stock issued. The Company records proceeds from early exercises as a liability and reclassifies the amount to equity as the repurchase right lapses. At December 31, 2018, 2017, and 2016, there were no unvested options resulting from early exercises. Aggregate intrinsic value represents the difference between the Company’s estimated or actual fair value of its common stock and the exercise price of outstanding “in-the-money” options. The aggregate intrinsic value of options exercised was $12.6 million, $0.8 million and $23,000 during the years ended December 31, 2018, 2017 and 2016, respectively. Based on the fair market value of the Company’s common stock at December 31, 2018, 2017 and 2016, the total intrinsic value of all outstanding options was $19.3 million, $15.9 million and $2.5 million, respectively. At December 31, 2018 and 2017, total unrecognized stock-based compensation cost related to unvested stock options was $3.3 million, and $0.8 million, respectively, which will be recognized ratably over a weighted-average period of 3.3 years and 3.2 years for each period. Cash received from the exercise of stock options during the years ended December 31, 2018, 2017 and 2016 was $0.6 million, $55,000 and $25,000, respectively. No income tax benefits from stock-based compensation arrangements have been recognized in the consolidated statements of operations. The fair value of stock option grants is set forth below and was determined using the Black-Scholes option pricing model with the following assumptions: Year Ended December 31, 2018 2017 2016 Fair value of common stock $23.72-$47.39 $3.06-$19.56 $0.85-$3.06 Expected term (in years) 6 5-6 2-10 Risk-free interest rate 2.60%-3.00% 1.85%-2.29% 0.75%-1.77% Expected volatility 64%-67% 55% 55% Expected dividend yield — — — In February 2005, the Company adopted the 2005 Stock Plan, as amended in January 2010 and November 2012 (the “2005 Plan”). Under the 2005 Plan provisions, the Company was authorized to grant incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock units, and shares of restricted stock. Following the effectiveness of the 2017 Plan in connection with the IPO, no further grants will be made under the 2005 Plan. A summary of stock option activities under the 2005 Plan and 2017 Plan during 2016, 2017 and 2018 is as follows: Number of Options Outstanding Weighted Average Exercise Price Outstanding at December 31, 2015 938,250 $ 0.90 Granted 272,769 $ 1.27 Exercised (33,395 ) $ 0.75 Canceled (47,483 ) $ 4.14 Outstanding at December 31, 2016 1,130,141 $ 0.86 Granted 261,476 $ 5.52 Exercised (74,984 ) $ 0.74 Canceled (22,505 ) $ 1.52 Outstanding at December 31, 2017 1,294,128 $ 1.79 Granted 157,078 $ 33.70 Exercised (609,985 ) $ 0.90 Canceled (21,035 ) $ 6.78 Outstanding at December 31, 2018 820,186 $ 8.44 Stock options outstanding, exercisable and vested were as follows: Outstanding at December 31, 2018 Weighted-average Remaining Contractual Life (years) Exercisable and Vested as of December 31, 2018 Weighted-average Remaining Contractual Life (years) Weighted-average Exercise Price 820,186 7.17 439,927 5.99 1.66 Outstanding at December 31, 2017 Weighted-average Remaining Contractual Life (years) Exercisable and Vested as of December 31, 2017 Weighted-average Remaining Contractual Life (years) Weighted-average Exercise Price 1,294,128 6.22 883,959 5 0.85 Outstanding at December 31, 2016 Weighted-average Remaining Contractual Life (years) Exercisable and Vested as of December 31, 2016 Weighted-average Remaining Contractual Life (years) Weighted-average Exercise Price 1,130,141 6.29 842,261 5.32 0.74 During the year ended December 31, 2018, the company granted non-employee directors restricted stock unit (“RSU”) awards totaling 17,881 shares of common stock, with vesting terms of approximately 12 months. The fair value of $28.45 per unit was calculated using the closing stock price on the date of grants. During the year ended December 31, 2018, the Company granted executive management RSU awards totaling 92,883 shares of common stock, with vesting terms of 35% upon the first anniversary and 21.667% on each of the three subsequent anniversaries. The weighted average fair value of $17.87 per unit was calculated using the closing stock price on the grant dates. During the year ended December 31, 2017, the company granted non-employee directors RSU awards totaling 47,312 shares of common stock, with vesting terms of approximately seven to ten months. The fair value of $11.50 to $16.96 per unit was calculated using the closing stock price on the date of grants. At December 31, 2018 and 2017, total unrecognized stock-based compensation cost related to RSUs was $1.4 million, and $0.3 million, respectively, which will be recognized ratably over a weighted-average period of 2.7 years and 0.4 years for each period. Our equity-based incentive plans include stock options, restricted stock units and other stock awards. The number of shares available for grant under these plans was 1,248,424 as of December 31, 2018. 2017 Employee Stock Purchase Plan In May 2017, the Board and the Company’s stockholders adopted the 2017 Employee Stock Purchase Plan (“2017 ESPP”), which became effective in connection with the Company’s IPO. The 2017 ESPP allows eligible employees to purchase shares of the Company’s common stock in an offering at a discount of the then-current trading price, up to the lesser of (1) 85% of the fair market value of the common stock on the first day of the IPO or (2) 85% of the fair market value of the common stock on the purchase date. The 2017 ESPP permits the maximum discounted purchase price permitted under U.S. tax rules, including a “lookback.” The 2017 ESPP initial offering period runs for approximately 24 months in length, and contains four 6-month purchase periods. An employee’s purchase rights terminate immediately upon termination of employment or other withdrawal from the 2017 ESPP. No participant will have the right to purchase shares of common stock in an amount that has a fair market value of more than $25,000 determined as of the first day of the applicable purchase period, for each calendar year. There are 200,000 shares of common stock reserved for issuance under the 2017 ESPP. In addition, the 2017 ESPP contains a provision which provides for an automatic annual share increase on January 1 of each year, in an amount equal to the lesser of (1) 2% of the total number of shares of common stock outstanding on December 31 st The Company accounts for employee stock purchases made under its 2017 ESPP using the estimate grant date fair value of accounting in accordance with ASC 718, Stock Compensation There were 83,605 shares issued during 2018 and 232,262 shares available under the 2017 ESPP as of December 31, 2018. Total stock-based compensation expense associated with the 2005 Plan, 2017 Plan and 2017 ESPP is recorded in the consolidated statements of operations and was allocated as follows (in thousands): Year Ended December 31, 2018 2017 2016 Costs $ 316 $ 75 $ 11 Sales and marketing 770 133 7 Research and development 272 69 18 General and administrative 1,110 351 47 Total $ 2,468 $ 628 $ 83 Stock-based compensation expense is recognized over the award’s expected vesting schedule. Forfeitures are recognized as and when they occur.

Benefit Plan

Benefit Plan	12 Months Ended
	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Benefit Plan	Note 16. Benefit Plan The Company sponsors a 401(k) plan to provide defined contribution retirement benefits for all eligible employees. Participants may contribute a portion of their compensation to the plan, subject to the limitations under the Internal Revenue Code. The Company is allowed to make 401(k) matching contributions as defined in the plan and as approved by the Board. The Company did not make any contributions to the plan during the years ended December 31, 2018, 2017 and 2016.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 17. Commitments and Contingencies The Company leases its principal executive offices in Newark, California, under a non-cancelable operating lease which expires in 2021. The Company recognizes rent expense on a straight-line basis over the expected lease term. The difference between cash payments required and rent expense is recorded as deferred rent. Total rent expense was $0.6 million for the year ended December 31, 2018 and $0.4 million for each of the years ended December 31, 2017 and 2016. The company also has data center non-cancelable contracts, that exceed one year. The following is a schedule of future minimum datacenter arrangements and lease payments under the non-cancelable commitments at December 31, 2018 (in thousands): Data Center Arrangements Operating Lease 2019 $ 213 $ 352 2020 71 357 2021 — 304 Total $ 284 $ 1,013 Contingencies On November 6, 2017 three individuals, Ken Fisher, Kevin Baxter and Fred Holmes (the “Contractors”), filed a complaint with the Superior Court of California, County of Alameda, alleging breach of contract, a breach of the implied covenant of good faith and fair dealing and violation of Section 17200 et seq. of the California Business and Professions Code, purportedly predicated on an alleged breach of Section 10b-5 of the Securities Exchange Act of 1934. On October 4, 2018, the parties reached a binding settlement. The Contractors filed a Notice of Unconditional Settlement on October 9, 2018, which gives them 45 days from October 4, 2018 to file a request for dismissal. The Contractors filed a request for dismissal on October 24, 2018 and such dismissal was entered as requested on October 24, 2018. On August 28, 2018, Silvon S. Simmons (the "Plaintiff") amended a complaint against the City of Rochester, New York and various city employees, filed in the United States District Court, Western District of New York, to add the Company and employees as a defendant. The amended complaint alleges conspiracy to violate plaintiff's civil rights, denial of the right to a fair trial, and malicious prosecution. The Plaintiff claims that ShotSpotter colluded with the City of Rochester to fabricate and create gunshot alert evidence to secure Plaintiff's conviction. On the basis of the allegations, the Plaintiff has petitioned for compensatory and punitive damages and other costs and expenses, including attorney's fees. The Company believes that the Plaintiff's claims are without merit and are disputing them vigorously. The Company may become subject to legal proceedings, as well as demands and claims that arise in the normal course of business. Such claims, even if not meritorious, could result in the expenditure of significant financial and management resources. The Company makes a provision for a liability relating to legal matters when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. These provisions are reviewed and adjusted to include the impacts of negotiations, estimated settlements, legal rulings, advice of legal counsel, and other information and events pertaining to a particular matter. An unfavorable outcome on any litigation matters could require payment of substantial damages, or, in connection with any intellectual property infringement claims, could require the Company to pay ongoing royalty payments or could prevent the Company from selling certain of our products. As a result, a settlement of, or an unfavorable outcome on, any of the matters referenced above or other litigation matters could have a material adverse effect on the Company’s business, operating results, financial condition and cash flows.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Note 18. Subsequent Events For the audited consolidated financial statements, management evaluated subsequent events through March 4, 2019, which is the date these consolidated financial statements were issued.

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding financial reporting. The consolidated financial statements include the results of the Company and its wholly-owned subsidiary, ShotSpotter (Pty) Ltd. All significant intercompany transactions have been eliminated during consolidation. In the opinion of management, the accompanying consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the financial position, results of operations, comprehensive loss, equity statement and cash flows for the full year 2018.
June 2017 Amended and Restated Certificate of Incorporation	June 2017 Amended and Restated Certificate of Incorporation Prior to the IPO, the Company’s Board of Directors (the “Board”) and stockholders approved an amendment (the “Charter Amendment”) to the Pre-IPO Certificate (as defined below) and an amended and restated certificate of incorporation (“Post-IPO Certificate”) that became effective on June 12, 2017. The Charter Amendment increased the number of authorized shares of common stock from 8,600,000 to 500,000,000. Under the Post-IPO Certificate, the Company is authorized to issue two classes of stock to be designated Common Stock and Preferred Stock. See Note 11, Capital Stock
March 2017 Amendment and Restatement of Certificate of Incorporation	March 2017 Amendment and Restatement of Certificate of Incorporation On March 27, 2017, the Company’s Board and stockholders approved an amendment and restatement of the Company’s then-existing certificate of incorporation (as so amended and restated, the “Pre-IPO Certificate”) to provide, among other changes, that each share of Series A-2 convertible preferred stock would automatically convert into 0.715548 shares of common stock upon the consummation of an initial public offering of the Company’s capital stock. All share and per share data related to balance sheet and net loss information in the accompanying consolidated financial statements and their related notes have been retroactively adjusted to give effect to the application of this conversion feature when presenting the Series A-2 convertible preferred stock on an as-converted basis. The Pre-IPO Certificate also provided for (1) an increase in the total number of authorized shares to 14,550,000 and (2) an increase in the number of authorized shares of common stock to 8,600,000, in each case to accommodate the new conversion feature for the outstanding shares of Series A-2 convertible preferred stock.
Reverse Stock Split and Amendment To Certificate of Incorporation	Reverse Stock Split and Amendment to Certificate of Incorporation In December 2016, the Board and stockholders approved an amendment and restatement of the Company’s then amended and restated certificate of incorporation to effect a one-for-17 reverse stock split of the outstanding shares of the Company’s capital stock, such that each 17 shares of capital stock issued and outstanding, automatically and without any action on the part of the respective holders thereof, combined into one share of the same class and series of capital stock. All share and per share data in the accompanying consolidated financial statements and their related notes for all periods presented have been retroactively adjusted to give effect to the reverse stock split.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and reported amounts of revenues and expenses during the reporting period. On an ongoing basis, management evaluates its significant estimates including the valuation of accounts receivable, the useful lives of tangible and intangible assets, fair values of intangible assets and goodwill, stock-based compensation expense, preferred stock warrant liabilities, and accounting for income taxes. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions it believes to be reasonable under the circumstances. Actual results could differ from those estimates and such differences could be material to the Company’s financial position and results of operations.
Revenue Recognition	Revenue Recognition The Company generates substantially all of its revenues from the sale of gunshot detection subscription services, in which gunshot data generated by Company-owned sensors and software is sold to customers through a cloud-based hosting application for a specified contract period. Typically, the initial contract period is one to five years in length. The subscription contract is generally noncancelable without cause. Generally, these service arrangements do not provide the customer with the right to take possession of the hardware or software supporting the subscription service at any time. A small portion of the Company’s revenues are generated from the delivery of setup services to install Company-owned sensors in the customer’s coverage area and other services including training and license to integrate with third-party applications. The Company generally invoices customers for 50% of the total contract value when the contract is fully executed and for the remaining 50% when the subscription service is operational and ready to go live – that is, when the customer has acknowledged the completion of all the deliverables in the signed customer acceptance form. The Company generally invoices subscription service renewals for 100% of the total contract value when the renewal contract is executed. For the public safety solution, the pricing model is based on a per-square-mile basis. For security solutions, the pricing model is on a customized-site basis. As a result of the process for invoicing contracts and renewals upon execution, cash flows from operations and accounts receivable can fluctuate due to timing of contract execution and timing of deployment. Prior to the adoption of Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606), Revenue Recognition • Persuasive evidence of an arrangement exists; • Delivery has occurred or services have been rendered; • The sales price is fixed or determinable; and • Collection of the related receivable is reasonably assured. Under ASC 605, the Company recognized subscription revenues ratably over the subscription period committed by the customer and commencing when the subscription service was fully operational and ready to go live, that is, upon completion of all deliverables stated in the signed customer acceptance form, assuming all other revenue recognition criteria were met. The Company recognized revenues from setup fees ratably based on the expected customer relationship period, typically over five years, which could extend beyond the initial contract period. In determining the expected customer relationship period, the Company considered specific customer details and renewal history with similar customers. If a customer declined to renew its subscription prior to the end of five years, then the remaining setup fees were immediately recognized. Effective January 1, 2018, after the adoption of Topic 606, the Company recognizes revenue upon the satisfaction of performance obligations. At contract inception, the Company assesses the services promised in its contracts with customers and identifies a performance obligation for each promise to transfer to the customer a good or service (or bundle of services) that is distinct. To identify the performance obligations, the Company considers all of the services promised in the contract regardless of whether they are explicitly stated or are implied by customary business practices. The Company determined that the subscription services, training, and licenses to integrate with third-party applications are each distinct services that represent separate performance obligations. The setup activities are not distinct from the subscription service and are combined into the subscription service performance obligation. However, setup fees may provide a material right to the customer that has influence over the customers' decision to renew. All setup fees are assessed on a quantitative and qualitative basis to determine whether they represent a distinct performance obligation. The total contract value is allocated to each performance obligation identified based on the standalone selling price of the service. Discounts are allocated pro-rata to the identified performance obligations. For contracts that have an original duration of one year or less, the Company uses the practical expedient applicable to such contracts and does not consider the time value of money. Revenues from subscription services are recognized ratably, on a straight-line basis, over the term of the subscription. Revenues from material rights are recognized ratably over the period in which they are determined to provide a material right to the customer, which is generally three years. Revenues from training and licenses to integrate with third-party applications are recognized upon delivery which generally occurs when the subscription service is operational and ready to go live and these amounts are immaterial. Subscription renewal fees are recognized ratably over the term of the renewal, which is typically one year. While most customers elect to renew their agreements, in some cases, they may not be able to obtain the proper approvals or funding to complete the renewal prior to expiration. For these customers, the Company stops recognizing subscription revenues at the end of the current contract term, even though services may continue to be provided for a period of time until the renewal process is completed. Once the renewal is complete, the Company recognizes subscription revenues for the period between the expiration of the term of the agreement and the completion of the renewal process in the month in which the renewal is executed. If a customer declines to renew its subscription prior to the end of three years, then the remaining fees from material rights, if any, are immediately recognized. As of January 1, 2018, upon the adoption of Topic 606, the Company had total short-term and long-term deferred revenue of $17.3 million. During the year ended December 31, 2018, the Company recognized $9.7 million in revenue from the beginning deferred revenue and $24.8 million from new billings, and added $41.4 million to total short-term and long-term deferred revenue from new billings. As of December 31, 2018, the Company has estimated remaining performance obligations for contractually committed revenues of $29.3 million, $20.9 million, $14.3 million, and $700,000 that will be recognized during the years ended December 31, 2019, 2020, 2021, and 2022 through 2024, respectively. The timing of revenue recognition includes estimates of go live dates for contracts not yet live. Contractually committed revenue includes deferred revenue as of December 31, 2018 and amounts under contract that will be invoiced after December 31, 2018. During the year ended December 31, 2018, the Company recognized revenues of $33.9 million from customers in the United States and $0.9 million from a customer in South Africa. Topic 606 also requires the capitalization of certain incremental costs of obtaining a contract, which impacts the period in which the Company records sales commissions expense. Historically, the Company recognized sales commissions expense upfront. Under Topic 606, the Company is required to capitalize these expenses. As there are not commensurate commissions earned on renewals of the subscription services, the Company concluded that the capitalized commissions are related to subscription services provided under both the initial contract and renewal periods. Therefore, the amortization period for the capitalized commissions is the customer life, which is determined to be five years. As the capitalized commissions are related to subscription services that are transferred over the customer's life, the Company amortizes the capitalized commissions on a straight-line basis of five years. For commissions that are earned on renewal contracts with an original duration of one year or less, the Company uses the practical expedient applicable to such commissions and recognizes the commissions immediately as expense instead of capitalizing. Amortization of capitalized commissions was $0.5 million for the year ended December 31, 2018 and was included in sales and marketing expense in the consolidated statements of operations.
Costs	Costs Costs include the cost of revenues and charges for impairment of property and equipment. Cost of revenues primarily includes depreciation expense associated with capitalized customer acoustic sensor networks, communication expenses, costs related to hosting our service application, costs related to operating our Incident Review Center (the “IRC”), providing remote and on-site customer support and maintenance and forensic services, certain personnel and related costs of operations, stock-based compensation and allocated overhead, which includes information technology, facility and equipment depreciation costs.
Advertising and Promotion Costs	Advertising and Promotion Costs Advertising and promotion costs are expensed as incurred. Advertising and promotion costs were $0.6 million for the year ended December 31, 2018 and $0.5 million for each of the years ended December 31, 2017 and 2016, and were included in sales and marketing expense in the consolidated statements of operations.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred and consisted primarily of salaries and benefits, consultant fees, certain facilities costs, and other direct costs associated with the continued development of the Company’s solutions.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents include all cash and highly liquid investments with an original maturity of three months or less. At December 31, 2018 and 2017, the Company’s cash and cash equivalents consisted of cash deposited in financial institutions.
Restricted Cash	Restricted Cash At December 31, 2018 and 2017, restricted cash consisted of certificates of deposit held at a financial institution as collateral for credit cards and letters of credit held by the Company.
Foreign Currency	Foreign Currency The functional currency for the Company’s foreign subsidiary, ShotSpotter (Pty) Ltd., is the local currency (South African Rand). The assets and liabilities of the subsidiary are translated into U.S. dollars using the exchange rate at the end of each balance sheet date. Revenues and expenses are translated at the average exchange rates for the period. Gains and losses from translations are recognized in foreign currency translation included in accumulated other comprehensive loss in the accompanying consolidated balance sheets. Foreign currency exchange gains and losses are recorded in other expense, net, in the accompanying consolidated statements of operations.
Accounts Receivable, net and Unbilled Revenue	Accounts Receivable, net and Unbilled Revenue Accounts receivable, net consist of trade accounts receivables from the Company’s customers, net of allowance for doubtful accounts if deemed necessary. Accounts receivable are recorded as the invoiced amount. The Company does not require collateral or other security for accounts receivable. Unbilled revenue consists of revenue recognized in advance of invoicing the customer. The Company periodically evaluates the collectability of its accounts receivable and provides an allowance for potential credit losses based on the Company’s historical experience. At December 31, 2018 and 2017, the Company did not have an allowance for potential credit losses as there were no estimated credit losses.
Concentrations of Risk	Concentrations of Risk Credit Risk Financial instruments that potentially subject the Company to concentration of credit risk consisted primarily of restricted cash, cash and cash equivalents and accounts receivable from trade customers. The Company maintains its cash deposits at three domestic and one international financial institutions. The Company is exposed to credit risk in the event of default by a financial institution to the extent that cash and cash equivalents are in excess of the amount insured by the Federal Deposit Insurance Corporation. The Company generally places its cash and cash equivalents with high-credit quality financial institutions. To date, the Company has not experienced any losses on its cash and cash equivalents. Concentration of Accounts Receivable At December 31, 2018, one customer accounted for 77%, of the Company’s account receivable. Fluctuations in accounts receivable result from timing of the Company’s execution of contracts and collection of related payments. At December 31, 2017, three customers accounted for 18%, 18% and 14% of the Company’s accounts receivable. Concentration of Revenues For the year ended December 31, 2018, two customers accounted for 22% and 15% of the Company’s revenues. For the year ended December 31, 2017, one customer accounted for 18% of the Company’s revenue. For the year ended December 31, 2016, two customers each accounted for 12% of the Company’s revenues. Concentration of Suppliers The Company relies on a limited number of suppliers and contract manufacturers. In particular, a single supplier is currently the sole manufacturer of the Company’s proprietary sensors.
Business Acquisitions	Business Acquisitions The Company allocates the fair value of purchase consideration to the tangible assets acquired, liabilities assumed and intangible assets acquired based on their estimated fair values. The excess of the fair value of purchase consideration over the fair values of these identifiable assets and liabilities is recorded as goodwill. When determining the fair values of assets acquired and liabilities assumed, management makes significant estimates and assumptions, especially with respect to intangible assets. Acquisition-related expenses are recognized separately from the business combination and are recognized as general and administrative expense as incurred.
Goodwill	Goodwill Following the acquisition of HunchLab (see Note 7, Business Acquisitions
Intangible Assets	Intangible Assets Intangible assets consisted of acquired patents and capitalized legal fees related to obtaining patents, as well as customer relationships as a result from the Company’s acquisition of HunchLab in 2018 (see Note 7, Business Acquisitions
Property and Equipment, net	Property and Equipment, net Property and equipment, net, is stated at cost, less accumulated depreciation and amortization. The Company depreciates property and equipment using the straight-line method over their estimated useful lives, ranging from three to five years. Leasehold improvements are amortized over the shorter of the asset’s useful life or the remaining lease term.
Accounting for Impairment of Long-Lived Assets	Accounting for Impairment of Long-Lived Assets The Company annually reviews long-lived assets for impairment or whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparing the carrying amount of the asset to the future undiscounted net cash flows which the asset is expected to generate. If such assets are determined to be impaired, the impairment to be recognized is measured as the amount by which the carrying amount of the assets exceeds the future undiscounted net cash flows arising from the assets. Assets to be disposed of are reported at the lower of their carrying amounts or fair value less cost to sell. During the year ended December 31, 2018, the Company recognized impairment expense of $0.7 million for the impairment of property and equipment primarily related to the remaining book value of indoor sensor inventory and indoor sensor networks installed at certain security customers. During the year ended December 31, 2017, the Company recognized impairment expense of $0.8 million for the impairment of property and equipment primarily related to the remaining net book value for deployed equipment that was presumed destroyed by hurricanes in September 2017. The Company did not record any impairment of long-lived assets during the year ended December 31, 2016.
Royalty Expense	Royalty Expense In 2009, the Company entered into a license agreement with a third party relating to a patented gunshot digital imaging system that facilitates integration with certain third-party systems. The terms of the license agreement require the Company to pay a one-time fee of $5,000 for each license sold to a customer allowing the customer to integrate their ShotSpotter service with a third-party application, such as a video management system, with a minimum annual amount due of $75,000. In 2018, 2017, and 2016, the Company incurred only the $75,000 minimum amount. The license agreement renews automatically on each subsequent year unless it is terminated in accordance with the agreement. The royalty fee due for each license sold to a customer is capitalized as property and equipment and amortized over the estimated useful life. The difference in royalty fees capitalized in property and equipment and the minimum annual payment is classified as general and administrative expense in the consolidated statements of operations and was $35,000, $60,000 and $35,000 for the years ended December 31, 2018, 2017, and 2016, respectively.
Convertible Preferred Stock Warrants	Convertible Preferred Stock Warrants The Company issued warrants exercisable for shares of Series B-1 convertible preferred stock, or for shares of common stock upon the automatic conversion of all outstanding series of preferred stock into common stock. These warrants were classified as a preferred stock warrant liability in the consolidated balance sheets, rather than stockholders’ equity, as they met the criteria to be classified as a derivative liability. The convertible preferred stock warrants were subject to remeasurement to fair value at each balance sheet date and any change in fair value is recognized as a component of other expense, net, in the consolidated statements of operations. The Company estimates the fair value of the warrants using an option pricing method (“OPM”) or probability weighed expected return method (“PWERM”) that incorporates the use of OPM, to allocate the estimated value of the Company. The OPM treats classes of stock as call options on a company’s enterprise value with exercise prices based on the liquidation preferences of convertible preferred stock. The OPM prices the call option using the Black-Scholes model. The PWERM relies on a forward-looking analysis to predict the possible future value of a company by weighing discrete future outcomes. Upon the closing of the IPO in 2017, the convertible preferred stock warrant liability was reclassified to additional paid-in capital. All preferred stock warrants were converted into common stock warrants.
Fair Value Measurements	Fair Value Measurements The Company uses a three-level hierarchy for fair value measurements based on the nature of inputs used in the valuation of an asset or liability as of the measurement date. The three-level hierarchy prioritizes, within the measurement of fair value, the use of market-based information over entity-specific information. Fair value focuses on an exit price and is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The inputs or methodology used for valuing financial instruments are not necessarily an indication of the risks associated with investing in those financial instruments. The three-level hierarchy for fair value measurements is defined as follows: Level I — Inputs to the valuation methodology are quoted prices (unadjusted) for identical assets or liabilities in active markets. Level II — Inputs to the valuation methodology include quoted prices for similar assets and liabilities in active markets, and inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the financial instrument. Level III — Inputs to the valuation methodology are unobservable and significant to the fair value measurement. An asset’s or a liability’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement.
Stock-Based Compensation	Stock-Based Compensation The Company generally grants options to purchase shares of its common stock to its employees and directors for a fixed number of shares with an exercise price equal to the fair value of the underlying shares at the grant date. Fair value is determined by the Board. The Company accounts for these options under ASC Topic 718, Compensation—Stock Compensation. Accordingly, all stock option grants are accounted for using the fair value method, and stock-based compensation expense is recognized as the underlying options vest. The Company uses the Black-Scholes option pricing model to measure the fair value of its stock options. Stock-based compensation for options granted to non-employees is measured on the date of performance at the fair value of the consideration received or the fair value of the equity instruments issued, whichever is more reliably measured. Compensation for options granted to non-employees is periodically remeasured as the underlying options vest. Prior to the IPO, given the absence of a public trading market for the Company’s common stock, the Board considered numerous objective and subjective factors to determine the fair value of the Company’s common stock each time stock option grants were approved. The factors include, but are not limited to: (i) the valuation of the Company’s common stock by an unrelated third party; (ii) the Company’s results of operations, financial position and capital resources; (iii) current economic indicators and outlook; (iv) competition for the Company’s solutions; and (v) the Company’s marketing methods. The Company estimated the grant date fair value of its common stock options using the following assumptions: Expected Term — The expected term represents the period that the stock-based compensation awards are expected to be outstanding. Since the Company did not have sufficient historical information to develop reasonable expectations about future exercise behavior, the Company used the simplified method to compute expected term, which reflects the weighted-average of time-to-vesting. Risk-Free Interest Rate — The risk-free interest rate is based on the yield on U.S. Treasury yield curve in effect at the grant date. Expected Volatility — Since the Company does not have a long trading history of its common stock, the expected volatility is derived from the average historical volatilities of publicly traded companies that are reasonably comparable to the Company’s own operations. Dividend Yield — After the IPO, the Company uses the market closing price of its common stock as traded on the Nasdaq Capital Market to determine fair value. The Company generally grants unvested restricted stock unit awards to non-employee directors for a fixed number of shares and a fixed vesting date. The restricted stock unit awards are valued using the closing price on the date of grant. Forfeitures are recognized as and when they occur.
Segment Information	Segment Information The Company has one operating segment with one business activity, providing gunshot detection systems. The Company’s chief operating decision maker is its Chief Executive Officer, who manages operations on a consolidated basis for purposes of allocating resources.
Income Taxes	Income Taxes The Company records income taxes in accordance with the liability method of accounting. Deferred taxes are recognized for the estimated taxes ultimately payable or recoverable based on enacted tax law. The Company establishes a valuation allowance to reduce the deferred tax assets when it is more likely than not that a deferred tax asset will not be realizable. Changes in tax rates are reflected in the tax provision as they occur. In accounting for uncertainty in income taxes, the Company recognizes the financial statement benefit of a tax position only after determining that the relevant tax authority would more likely than not sustain the position following an audit. For tax positions meeting the more likely than not threshold, the amount recognized in the consolidated financial statements is the largest benefit that has a greater than 50 percent likelihood of being realized upon ultimate settlement with the relevant tax authority.
Net Loss per Share Attributable to Common Stockholders	Net Loss per Share Attributable to Common Stockholders Basic net loss per share is calculated by dividing net loss by the weighted-average number of common shares outstanding during the period. Diluted net loss per share is computed by dividing net loss by the weighted-average number of common shares and common stock equivalents outstanding during the period. Common stock equivalents are only included when their effect is dilutive. Common stock equivalents and unvested restricted stock units are potentially dilutive securities and include convertible preferred stock, warrants and outstanding stock options. These potentially dilutive securities are excluded from the computation of diluted net loss per share if their inclusion would be anti-dilutive. For all periods presented, there is no difference in the number of shares used to compute basic and dilutive shares outstanding due to the Company’s net loss position.
Accounting Pronouncements Recently Adopted	Accounting Pronouncements Recently Adopted Effective January 1, 2018, the Company adopted Topic 606. The impact from the adoption of Topic 606 was as follows: Year Ended December 31, 2018 As Reported Effect of Change Increase/ (Decrease) Amounts Without Adoption of Topic 606 Revenues $ 34,753 $ 392 $ 34,361 Costs $ 15,532 $ — $ 15,532 Gross profit $ 19,221 $ 392 $ 18,829 Sales and marketing expense $ 8,377 $ (438 ) $ 8,815 Operating loss $ (2,568 ) $ (830 ) $ (3,398 ) Net loss $ (2,725 ) $ (830 ) $ (3,555 ) As of December 31, 2018 As Reported Effect of Change Increase/ (Decrease) Amounts Without Adoption of Topic 606 Assets Prepaid expenses and other current assets $ 1,527 $ 629 $ 898 Other assets $ 1,922 $ 1,560 $ 362 Total assets $ 47,119 $ 2,189 $ 44,930 Liabilities Deferred revenue, short term $ 23,102 $ 1,043 $ 22,059 Accrued expenses and other current liabilities $ 4,427 $ 82 $ 4,345 Total current liabilities $ 28,836 $ 1,125 $ 27,711 Deferred revenue, long term $ 1,060 $ (913 ) $ 1,973 Total liabilities $ 29,972 $ 212 $ 29,760 In January 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230) Classification of Certain Cash Receipts and Cash Payments In October 2016, the FASB issued ASU 2016-16, Intra-Entity Transfers of Assets Other Than Inventory In November 2016, the FASB issued ASU 2016-18, Restricted Cash In May 2017, the FASB issued ASU 2017-09, Scope of Modification Accounting Compensation – Stock Compensation
Recent Accounting Pronouncements Not Yet Effective	Recent Accounting Pronouncements Not Yet Effective In February 2016, the FASB issued ASU 2016-02, Leases At transition, lessees and lessors may elect to apply a package of practical expedients permitting entities not to reassess: (i) whether any expired or existing contracts are or contain leases; (ii) lease classification for any expired or existing leases and (iii) whether initial direct costs for any expired or existing leases qualify for capitalization under the amended guidance. These practical expedients must be elected as a package and consistently applied. The Company has elected to apply the package of practical expedients upon adoption. The Company identified its operating lease for its corporate headquarters office impacted by the new standard and is currently in the process of updating its business processes and related policies, systems and controls to support recognition and disclosure under the new standard. Upon adoption of the amended guidance, the Company expects to recognize right-of-use assets and related lease liabilities of approximately $0.8 million for its contracts which contain an operating lease. The Company currently does not expect the amended guidance to have any other material impacts on our consolidated financial statements. In July 2017, the FASB issued ASU 2017-11 , Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), Derivatives and Hedging (Topic 815).
Employee Stock Purchase Plan	The Company accounts for employee stock purchases made under its 2017 ESPP using the estimate grant date fair value of accounting in accordance with ASC 718, Stock Compensation

Basis of Presentation and Sum_3

Basis of Presentation and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Adoption of Topic 606
Summary of Impact from Adoption of Topic 606	The impact from the adoption of Topic 606 was as follows: Year Ended December 31, 2018 As Reported Effect of Change Increase/ (Decrease) Amounts Without Adoption of Topic 606 Revenues $ 34,753 $ 392 $ 34,361 Costs $ 15,532 $ — $ 15,532 Gross profit $ 19,221 $ 392 $ 18,829 Sales and marketing expense $ 8,377 $ (438 ) $ 8,815 Operating loss $ (2,568 ) $ (830 ) $ (3,398 ) Net loss $ (2,725 ) $ (830 ) $ (3,555 ) As of December 31, 2018 As Reported Effect of Change Increase/ (Decrease) Amounts Without Adoption of Topic 606 Assets Prepaid expenses and other current assets $ 1,527 $ 629 $ 898 Other assets $ 1,922 $ 1,560 $ 362 Total assets $ 47,119 $ 2,189 $ 44,930 Liabilities Deferred revenue, short term $ 23,102 $ 1,043 $ 22,059 Accrued expenses and other current liabilities $ 4,427 $ 82 $ 4,345 Total current liabilities $ 28,836 $ 1,125 $ 27,711 Deferred revenue, long term $ 1,060 $ (913 ) $ 1,973 Total liabilities $ 29,972 $ 212 $ 29,760

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Summary of Changes in Fair Value of Convertible Preferred Stock Warrant Liability and Contingent Consideration	The changes in the fair value of the convertible preferred stock warrant liability and changes in the fair value of contingent consideration are summarized below (in thousands): Fair Value Measurements at Reporting Date Using Level III Inputs Fair value at December 31, 2015 $ 1,351 Change in fair value recorded in other expense, net 524 Fair value at December 31, 2016 $ 1,875 Issuance of convertible preferred stock warrants 111 Change in fair value recorded in other expense, net 3,725 Reclassification of unexercised warrant into additional paid-in capital upon the IPO (5,711 ) Fair value at December 31, 2017 $ — Contingent consideration 750 Fair value at December 31, 2018 $ 750

Intangible Assets, Net (Tables)

Intangible Assets, Net (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets Net	Intangible assets, net, consisted of the following (in thousands): December 31, 2018 Gross Accumulated Amortization Net Patents $ 997 $ (909 ) $ 88 Customer relationship 160 (6 ) 154 $ 1,157 $ (915 ) $ 242 December 31, 2017 Gross Accumulated Amortization Net Patents $ 949 $ (854 ) $ 95

Details of Certain Consolidat_2

Details of Certain Consolidated Balance Sheet Accounts (Tables)	12 Months Ended
	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets (in thousands): December 31, 2018 2017 Prepaid software and licenses $ 388 $ 407 Prepaid insurance 275 211 Other prepaid expenses 169 137 Deferred commissions 629 — Other 66 84 $ 1,527 $ 839
Schedule of Other Assets	Other assets (in thousands): December 31, 2018 2017 Deferred commissions $ 1,560 $ — Other 362 143 $ 1,922 $ 143
Schedule of Property and Equipment, Net	Property and equipment, net (in thousands): December 31, 2018 2017 Deployed equipment $ 24,767 $ 17,091 Computer equipment 1,272 1,123 Software 1,239 312 Furniture and fixtures 210 165 Leasehold improvements 234 202 Construction in progress 953 1,456 $ 28,675 $ 20,349 Accumulated depreciation and amortization (12,171 ) (8,753 ) $ 16,504 $ 11,596
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities (in thousands): December 31, 2018 2017 Payroll liabilities $ 1,859 $ 1,697 Accrued employee paid time off 558 469 Accrued commissions 43 199 Accrued ESPP 143 115 Royalties payable 130 125 Professional fees 396 328 Sales/ use tax payable 273 406 Contingent consideration 750 — Other 275 476 $ 4,427 $ 3,815

Business Acquisitions (Tables)

Business Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Summary of Purchase Price Allocation	The following table presents the purchase price allocation (in thousands): Accounts receivable $ 114 Prepaid expense 4 Deferred revenue, short term (120 ) Accounts payable (26 ) Software technology 950 Customer relationships 160 Goodwill 1,379 Total purchase consideration $ 2,461
Components of Identifiable Technology and Intangible Assets and Estimated Useful Lives	The following table presents the components of the identifiable technology and intangible assets and the estimated useful lives (in thousands): Fair Value Useful Life Software technology $ 950 5 years Customer relationships 160 7 years Total identifiable technology and intangible assets $ 1,110

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Domestic and Foreign Components of Net Loss	The domestic and foreign components of net loss were as follows (in thousands): Year Ended December 31, 2018 2017 2016 Domestic $ (3,083 ) $ (10,125 ) $ (6,744 ) Foreign 345 305 (116 ) Net loss $ (2,738 ) $ (9,820 ) $ (6,860 )
Schedule of Provision for Income Tax	The provision for income tax consists of the following (in thousands): Year Ended December 31, ​ 2018 2017 2016 Current: Federal $ — $ — $ — State — — — Foreign (13 ) 160 — Total (13 ) 160 — Deferred: Federal — — — State — — — Foreign — — — Total — — — Total tax expense $ (13 ) $ 160 $ —
Schedule of Reconciliation of Statutory Federal Income Tax Rate to Net Income Taxes	A reconciliation of income taxes at the statutory federal income tax rate to net income taxes included in the accompanying consolidated statements of operations is as follows (in thousands): December 31, 2018 2017 2016 Income tax at statutory rate $ (575 ) $ (3,339 ) $ (2,331 ) Change in valuation allowance 1,595 (8,354 ) 2,146 Change in tax rate — 9,788 — Change in deferreds 7 (39 ) — State tax (309 ) 536 9 Mark-to-market on warrants — 1,267 178 Stock-based compensation (615 ) 84 24 Research and development credit (220 ) (62 ) (88 ) Foreign rate differential (86 ) 56 40 Subpart F - transition tax 81 68 — Lobbying 78 79 — Other 31 76 22 Total $ (13 ) $ 160 $ —
Schedule of Company's Deferred Tax Assets and Liabilities	Temporary differences that gave rise to significant portions of the Company’s deferred tax assets and liabilities as of December 31, 2018 and 2017 were as follows (in thousands): Year Ended December 31, 2018 2017 Deferred tax assets: Net operating losses $ 21,461 $ 20,139 Credits 1,969 1,654 Accruals and reserves 285 643 Deferred revenue and contract costs 458 464 Gross deferred tax assets 24,173 22,900 Valuation allowance (23,710 ) (22,789 ) Net deferred tax assets 463 111 Deferred tax liabilities: Fixed assets and intangibles (545 ) (111 ) Total deferred tax liabilities, net $ (82 ) $ —
Schedule of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amounts of unrecognized tax benefits is as follows (in thousands): Balance as of December 31, 2016 $ 574 Increases for current year tax positions 46 Increases for prior year tax positions — Balance as of December 31, 2017 620 Increases for current year tax positions 114 Increases for prior year tax positions — Balance as of December 31, 2018 $ 734

Capital Stock (Tables)

Capital Stock (Tables)	12 Months Ended
	Dec. 31, 2018
Stockholders Equity Note [Abstract]
Schedule of Stock by Class	Immediately prior to the IPO, the Company had the following outstanding convertible preferred stock: Shares Authorized Shares Issued and Outstanding Aggregate Liquidation Preference (in thousands) Series B-1 4,773,000 3,848,023 $ 22,575 Series A-2 1,177,000 1,176,423 20,000 $ 42,575
Schedule of Common Stock Reserved for Future Issuance	At December 31, 2018, shares of common stock reserved for future issuance were as follows: December 31, 2018 Options outstanding 820,186 Shares available for future grant 1,248,424 Unvested restricted stock units 110,764 Warrants to purchase common stock 163,713 Total 2,343,087

Net Loss per Share (Tables)

Net Loss per Share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Summary of Computation of Basic and Diluted Net Loss per Share	The following table summarizes the computation of basic and diluted net loss per share (in thousands, except share and per share data): Year Ended December 31, 2018 2017 2016 Numerator: Net loss $ (2,725 ) $ (9,980 ) $ (6,860 ) Denominator: Weighted-average shares outstanding, basic and diluted 10,569,007 6,197,775 1,602,402 Net loss per share $ (0.26 ) $ (1.61 ) $ (4.28 )
Schedule of Anti-dilutive Shares Outstanding Excluded in Calculation of Diluted Net Loss per Share	The following potentially dilutive shares outstanding at the end of the periods presented were excluded in the calculation of diluted net loss per share as the effect would have been anti-dilutive: Year Ended December 31, 2018 2017 2016 Options to purchase common stock 820,186 1,294,128 1,130,141 Unvested restricted stock units 110,764 47,312 — Warrants to purchase Series B-1 convertible preferred or common stock 163,713 468,278 680,027 Series B-1 convertible preferred stock (as-converted) — — 3,848,023 Series A-2 convertible preferred stock (as-converted) — — 841,730 Total 1,094,663 1,809,718 6,499,921

Convertible Preferred Stock W_2

Convertible Preferred Stock Warrants and Common Stock Warrants (Tables)	12 Months Ended
	Dec. 31, 2018
Warrants And Rights Note Disclosure [Abstract]
Schedule of Warrants Issued and Outstanding	At December 31, 2016, the Company had the following Series B-1 convertible preferred stock warrants issued and outstanding (in thousands, except share and per share data): Warrant Class Shares Fair Value Issuance Date Price per Share Expiration Date Series B-1 25,568 $ 303 June 2012 $ 5.8667 June 2022 Series B-1 167,428 $ 263 July 2012 $ 5.8667 July 2019 Series B-1 145,801 $ 46 August 2012 $ 5.8667 August 2019 Series B-1 10,517 $ 19 November 2012 $ 5.8667 November 2022 Series B-1 156,851 $ 929 February 2014 $ 0.1700 February 2021 Series B-1 173,862 $ 315 September 2015 $ 5.8667 September 2025 Total 680,027 $ 1,875 At December 31, 2018 and 2017, the Company had the following common stock warrants issued and outstanding: Shares Warrant Class 2018 2017 Issuance Date Price per Share Expiration Date Common stock warrant 3,766 165,925 July 2012 $ 5.8667 July 2019 Common stock warrant 25,231 61,502 August 2012 $ 5.8667 August 2019 Common stock warrant 50,716 156,851 February 2014 $ 0.1700 February 2021 Common stock warrant (1) 84,000 84,000 June 2017 $ 13.2000 June 2020 163,713 468,278 (1 ) This warrant was issued to the Company’s lead underwriter in connection with the IPO.

Equity Incentive Plans (Tables)

Equity Incentive Plans (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Fair Value of Stock Option Grants Valuation Assumptions by Block-Scholes Option Pricing Model	The fair value of stock option grants is set forth below and was determined using the Black-Scholes option pricing model with the following assumptions: Year Ended December 31, 2018 2017 2016 Fair value of common stock $23.72-$47.39 $3.06-$19.56 $0.85-$3.06 Expected term (in years) 6 5-6 2-10 Risk-free interest rate 2.60%-3.00% 1.85%-2.29% 0.75%-1.77% Expected volatility 64%-67% 55% 55% Expected dividend yield — — —
Schedule of Stock Option Activity	A summary of stock option activities under the 2005 Plan and 2017 Plan during 2016, 2017 and 2018 is as follows: Number of Options Outstanding Weighted Average Exercise Price Outstanding at December 31, 2015 938,250 $ 0.90 Granted 272,769 $ 1.27 Exercised (33,395 ) $ 0.75 Canceled (47,483 ) $ 4.14 Outstanding at December 31, 2016 1,130,141 $ 0.86 Granted 261,476 $ 5.52 Exercised (74,984 ) $ 0.74 Canceled (22,505 ) $ 1.52 Outstanding at December 31, 2017 1,294,128 $ 1.79 Granted 157,078 $ 33.70 Exercised (609,985 ) $ 0.90 Canceled (21,035 ) $ 6.78 Outstanding at December 31, 2018 820,186 $ 8.44
Schedule of Stock Options Outstanding, Exercisable and Vested	Stock options outstanding, exercisable and vested were as follows: Outstanding at December 31, 2018 Weighted-average Remaining Contractual Life (years) Exercisable and Vested as of December 31, 2018 Weighted-average Remaining Contractual Life (years) Weighted-average Exercise Price 820,186 7.17 439,927 5.99 1.66 Outstanding at December 31, 2017 Weighted-average Remaining Contractual Life (years) Exercisable and Vested as of December 31, 2017 Weighted-average Remaining Contractual Life (years) Weighted-average Exercise Price 1,294,128 6.22 883,959 5 0.85 Outstanding at December 31, 2016 Weighted-average Remaining Contractual Life (years) Exercisable and Vested as of December 31, 2016 Weighted-average Remaining Contractual Life (years) Weighted-average Exercise Price 1,130,141 6.29 842,261 5.32 0.74
Schedule of Stock-Based Compensation Expense Recorded in Consolidated Statements of Operations	Total stock-based compensation expense associated with the 2005 Plan, 2017 Plan and 2017 ESPP is recorded in the consolidated statements of operations and was allocated as follows (in thousands): Year Ended December 31, 2018 2017 2016 Costs $ 316 $ 75 $ 11 Sales and marketing 770 133 7 Research and development 272 69 18 General and administrative 1,110 351 47 Total $ 2,468 $ 628 $ 83

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Data Center Arrangements and Lease Payments Under Non-cancelable Commitments	The following is a schedule of future minimum datacenter arrangements and lease payments under the non-cancelable commitments at December 31, 2018 (in thousands): Data Center Arrangements Operating Lease 2019 $ 213 $ 352 2020 71 357 2021 — 304 Total $ 284 $ 1,013

Organization and Description _2

Organization and Description of Business - Additional Information (Details)	Dec. 31, 2018CitySubsidiary
ShotSpotter (Pty) Ltd | South Africa
Business And Nature Of Operations [Line Items]
Number of subsidiary | Subsidiary	1
Shot Spotter Flex
Business And Nature Of Operations [Line Items]
Number of trusted cities | City	95

Initial Public Offering - Addit

Initial Public Offering - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Initial Public Offering [Line Items]
Net proceeds from Initial public offering excluding underwriting discounts and commissions	$ 32,400,000		$ 32,426,000
Loss on remeasurement of convertible preferred stock warrant liability			3,725,000	$ 524,000
Reclassification of convertible preferred stock warrant liability into additional paid-in capital	$ 5,700,000		5,711,000
Offering cost incurred excluding underwriting commissions and discounts			$ 1,870,000
Common Stock
Initial Public Offering [Line Items]
Conversion of preferred stock into common stock, shares	4,689,753		4,689,753
Additional Paid-in Capital
Initial Public Offering [Line Items]
Reclassification of convertible preferred stock warrant liability into additional paid-in capital	$ 42,100,000		$ 42,100,000
Offering cost incurred excluding underwriting commissions and discounts	$ 1,900,000		$ 1,870,000
Maximum
Initial Public Offering [Line Items]
Number of shares called by warrant	84,000
Minimum
Initial Public Offering [Line Items]
Net proceeds from Initial public offering excluding underwriting discounts and commissions	$ 25,000,000
Other Expense, Net
Initial Public Offering [Line Items]
Loss on remeasurement of convertible preferred stock warrant liability		$ 3,700,000
IPO
Initial Public Offering [Line Items]
Sale of stock, shares	3,220,000
Price per share	$ 11
IPO | Maximum
Initial Public Offering [Line Items]
Number of shares called by warrant	84,000

Basis of Presentation and Sum_4

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details)	Oct. 03, 2018	Jan. 01, 2018USD ($)	Dec. 31, 2016	Dec. 31, 2018USD ($)FinancialInstitutionCustomerSegmentBusinessshares	Dec. 31, 2017USD ($)Customershares	Dec. 31, 2016USD ($)Customer	Jan. 01, 2019USD ($)	Jun. 12, 2017shares	Mar. 27, 2017shares	Dec. 31, 2009USD ($)
Accounting Policies [Line Items]
Number of authorized shares of common stock | shares				500,000,000	500,000,000
Percentage of contract price invoiced to customer on contract signed				50.00%
Percentage of contract price invoiced to customer on subscription service operational and ready to go live				50.00%
Percentage of contract value invoiced subscription service renewals on renewal contract executed				100.00%
Deferred revenue added from new billings				$ 41,400,000
Revenues				34,753,000	$ 23,763,000	$ 15,507,000
Allowance for potential credit losses				0	0
Impairment of long-lived assets held for use				0.7
Impairment of long-lived assets to be disposed of						0
One-time license fee payable for each license sold to customer										$ 5,000
Minimum annual amount due under license agreement										$ 75,000
Minimum amount incurred under license agreement				$ 75,000	75,000	75,000
Expected dividend yield				0.00%
Number of operating segment | Segment				1
Number of business activity | Business				1
Description of uncertain income tax position				For tax positions meeting the more likely than not threshold, the amount recognized in the consolidated financial statements is the largest benefit that has a greater than 50 percent likelihood of being realized upon ultimate settlement with the relevant tax authority.
Accumulated deficit				$ (97,377,000)	(97,595,000)
Accrued expenses and other current liabilities				$ (246,000)	1,535,000	$ 1,049,000
Hurricane
Accounting Policies [Line Items]
Impairment of long-lived assets held for use					$ 800,000
Software Technology | HunchLab
Accounting Policies [Line Items]
Property and equipment estimated useful lives				5 years
Patents
Accounting Policies [Line Items]
Estimated useful life of intangible assets				3 years
Customer Relationships
Accounting Policies [Line Items]
Estimated useful life of intangible assets				7 years
Customer Relationships | HunchLab
Accounting Policies [Line Items]
Estimated useful life of intangible assets	7 years
Customer Concentration Risk | Accounts Receivable
Accounting Policies [Line Items]
Number of customers | Customer				1	3
Customer Concentration Risk | Revenues
Accounting Policies [Line Items]
Number of customers | Customer				2	1	2
Customer Concentration Risk | Customer One | Accounts Receivable
Accounting Policies [Line Items]
Concentration risk percentage				77.00%	18.00%
Customer Concentration Risk | Customer One | Revenues
Accounting Policies [Line Items]
Concentration risk percentage				22.00%	18.00%	12.00%
Customer Concentration Risk | Customer Two | Accounts Receivable
Accounting Policies [Line Items]
Concentration risk percentage					18.00%
Customer Concentration Risk | Customer Two | Revenues
Accounting Policies [Line Items]
Concentration risk percentage				15.00%		12.00%
Customer Concentration Risk | Customer Three | Accounts Receivable
Accounting Policies [Line Items]
Concentration risk percentage					14.00%
Sales and Marketing Expense
Accounting Policies [Line Items]
Advertising and promotion costs				$ 600,000	$ 500,000	$ 500,000
General and Administrative Expense
Accounting Policies [Line Items]
Royalty expense				35,000	$ 60,000	$ 35,000
United States
Accounting Policies [Line Items]
Revenues				$ 33,900,000
United States | Credit Concentration Risk
Accounting Policies [Line Items]
Number of financial institutions at which cash deposits are maintained | FinancialInstitution				3
South Africa
Accounting Policies [Line Items]
Revenues				$ 900,000
International | Credit Concentration Risk
Accounting Policies [Line Items]
Number of financial institutions at which cash deposits are maintained | FinancialInstitution				1
Recognition from Beginning Deferred Revenue
Accounting Policies [Line Items]
Deferred revenue recognized				$ 9,700,000
Recognition from New Billings of Deferred Revenue
Accounting Policies [Line Items]
Deferred revenue recognized				$ 24,800,000
Adoption of Topic 606
Accounting Policies [Line Items]
Revenues material right recognition period				3 years
Subscription renewal fees recognition period				1 year
Deferred revenue		$ 17,300,000
Capitalized commissions, amortization period				5 years
Amortization of capitalized commissions				$ 500,000
Adoption of Topic 606 | Effect of Change Increase/(Decrease)
Accounting Policies [Line Items]
Deferred revenue		(1,200,000)
Revenues				$ 392,000
Accumulated deficit		2,900,000
Accrued expenses and other current liabilities		100,000
Capitalization of commissions		$ 1,800,000
Adoption of Topic 842 | Scenario Plan
Accounting Policies [Line Items]
Operating lease, right-of-use assets							$ 800,000
Operating lease, liabilities							$ 800,000
Minimum
Accounting Policies [Line Items]
Subscription services initial contract period				1 year
Property and equipment estimated useful lives				3 years
Maximum
Accounting Policies [Line Items]
Subscription services initial contract period				5 years
Expected customer relationship period				5 years
Highly liquid investments maturity period				3 months
Property and equipment estimated useful lives				5 years
Amended and Restated Certificate of Incorporation
Accounting Policies [Line Items]
Number of authorized shares of common stock | shares								500,000,000	8,600,000
Total number of authorized shares | shares									14,550,000
Reverse stock split, description				one-for-17 reverse stock split of the outstanding shares of the Company’s capital stock, such that each 17 shares of capital stock issued and outstanding, automatically and without any action on the part of the respective holders thereof, combined into one share of the same class and series of capital stock.
Reverse stock split, conversion ratio			0.0588
Amended and Restated Certificate of Incorporation | Series A-2 Convertible Preferred Stock
Accounting Policies [Line Items]
Conversion of preferred stock into common stock | shares									0.715548
Convertible preferred stock, terms of conversion				to provide, among other changes, that each share of Series A-2 convertible preferred stock would automatically convert into 0.715548 shares of common stock upon the consummation of an initial public offering of the Company’s capital stock.

Basis of Presentation and Sum_5

Basis of Presentation and Summary of Significant Accounting Policies - Estimated Remaining Performance Obligations - Additional Information (Details)	Dec. 31, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-01-01
Accounting Policies [Line Items]
Estimated remaining performance obligations for contractually committed revenues	$ 29,300,000
Estimated remaining performance obligations for contractually committed revenues recognition period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01
Accounting Policies [Line Items]
Estimated remaining performance obligations for contractually committed revenues	$ 20,900,000
Estimated remaining performance obligations for contractually committed revenues recognition period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Accounting Policies [Line Items]
Estimated remaining performance obligations for contractually committed revenues	$ 14,300,000
Estimated remaining performance obligations for contractually committed revenues recognition period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Accounting Policies [Line Items]
Estimated remaining performance obligations for contractually committed revenues	$ 700,000
Estimated remaining performance obligations for contractually committed revenues recognition period	3 years

Basis of Presentation and Sum_6

Basis of Presentation and Summary of Significant Accounting Policies - Summary of Impact from Adoption of Topic 606 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	$ 34,753	$ 23,763	$ 15,507
Costs	15,532	12,163	9,549
Gross profit	19,221	11,600	5,958
Sales and marketing	8,377	6,179	4,475
Operating loss	(2,568)	(4,333)	(4,972)
Net loss	(2,725)	(9,980)	$ (6,860)
Assets
Prepaid expenses and other current assets	1,527	839
Other assets	1,922	143
Total assets	47,119	36,198
Liabilities
Deferred revenue, short term	23,102
Accrued expenses and other current liabilities	4,427
Total current liabilities	28,836	21,222
Deferred revenue, long term	1,060
Total liabilities	29,972	$ 24,036
Adoption of Topic 606 | Effect of Change Increase/(Decrease)
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	392
Gross profit	392
Sales and marketing	(438)
Operating loss	(830)
Net loss	(830)
Assets
Prepaid expenses and other current assets	629
Other assets	1,560
Total assets	2,189
Liabilities
Deferred revenue, short term	1,043
Accrued expenses and other current liabilities	82
Total current liabilities	1,125
Deferred revenue, long term	(913)
Total liabilities	212
Adoption of Topic 606 | Amounts Without Adoption of Topic 606
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	34,361
Costs	15,532
Gross profit	18,829
Sales and marketing	8,815
Operating loss	(3,398)
Net loss	(3,555)
Assets
Prepaid expenses and other current assets	898
Other assets	362
Total assets	44,930
Liabilities
Deferred revenue, short term	22,059
Accrued expenses and other current liabilities	4,345
Total current liabilities	27,711
Deferred revenue, long term	1,973
Total liabilities	$ 29,760

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Loss on remeasurement of convertible preferred stock warrant liability			$ 3,725,000	$ 524,000
Reclassification of convertible preferred stock warrant liability into additional paid-in capital	$ 5,700,000		$ 5,711,000
Transfers into or out of level 3		$ 0
Other Expense, Net
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Loss on remeasurement of convertible preferred stock warrant liability		$ 3,700,000

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Changes in Fair Value of Convertible Preferred Stock Warrant Liability and Contingent Consideration (Details) - Fair Value Measurements Recurring - Level 3 - Convertible Preferred Stock Warrant Liability - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance, fair value	$ 0	$ 1,875	$ 1,351
Issuance of convertible preferred stock warrants		111
Change in fair value recorded in other expense, net		3,725	524
Reclassification of unexercised warrant into additional paid-in capital upon the IPO		(5,711)
Contingent consideration	750
Ending balance, fair value	$ 750	$ 0	$ 1,875

Intangible Assets, Net - Schedu

Intangible Assets, Net - Schedule of Intangible Assets Net (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Finite Lived Intangible Assets [Line Items]
Gross	$ 1,157
Accumulated Amortization	(915)
Net	242	$ 95
Patents
Finite Lived Intangible Assets [Line Items]
Gross	997	949
Accumulated Amortization	(909)	(854)
Net	88	$ 95
Customer Relationship
Finite Lived Intangible Assets [Line Items]
Gross	160
Accumulated Amortization	(6)
Net	$ 154

Intangible Assets, Net - Additi

Intangible Assets, Net - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization expense	$ 61,000	$ 47,000	$ 37,000

Details of Certain Consolidat_3

Details of Certain Consolidated Balance Sheet Accounts - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Prepaid Expense And Other Assets Current [Abstract]
Prepaid software and licenses	$ 388	$ 407
Prepaid insurance	275	211
Other prepaid expenses	169	137
Deferred commissions	629
Other	66	84
Total	$ 1,527	$ 839

Details of Certain Consolidat_4

Details of Certain Consolidated Balance Sheet Accounts - Schedule of Other Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other Assets Noncurrent Disclosure [Abstract]
Deferred commissions	$ 1,560
Other	362	$ 143
Total other assets	$ 1,922	$ 143

Details of Certain Consolidat_5

Details of Certain Consolidated Balance Sheet Accounts - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 28,675	$ 20,349
Accumulated depreciation and amortization	(12,171)	(8,753)
Property and equipment, net	16,504	11,596
Deployed Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	24,767	17,091
Computer Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	1,272	1,123
Software
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	1,239	312
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	210	165
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	234	202
Construction in Progress
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 953	$ 1,456

Details of Certain Consolidat_6

Details of Certain Consolidated Balance Sheet Accounts - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accrued Expenses And Other Current Liabilities [Abstract]
Payroll liabilities	$ 1,859	$ 1,697
Accrued employee paid time off	558	469
Accrued commissions	43	199
Accrued ESPP	143	115
Royalties payable	130	125
Professional fees	396	328
Sales/ use tax payable	273	406
Contingent consideration	750
Other	275	476
Accrued expenses and other current liabilities	$ 4,427	$ 3,815

Business Acquisitions - Additio

Business Acquisitions - Additional Information (Details) - USD ($)	Oct. 03, 2018	Dec. 31, 2018
Business Acquisition [Line Items]
Business acquisition purchase consideration in cash		$ 1,711,000
HunchLab
Business Acquisition [Line Items]
Business acquisition date	Oct. 3, 2018
Business acquisitions purchase consideration	$ 2,500,000
Business acquisition purchase consideration in cash	$ 1,700,000
Revenue number of years on the base of business acquisition	3 years
Percentage of discounted cash flows	25.50%
Acquisition related expenses	$ 200,000
HunchLab | Maximum
Business Acquisition [Line Items]
Business acquisition contingent earnout payable in cash	$ 750,000

Business Acquisitions - Summary

Business Acquisitions - Summary of Purchase Price Allocation (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Oct. 03, 2018
Business Acquisition [Line Items]
Goodwill	$ 1,379
HunchLab
Business Acquisition [Line Items]
Accounts receivable		$ 114
Prepaid expense		4
Deferred revenue, short term		(120)
Accounts payable		(26)
Identifiable technology and intangible assets		1,110
Goodwill		1,379
Total purchase consideration		2,461
Software Technology | HunchLab
Business Acquisition [Line Items]
Identifiable technology and intangible assets		950
Customer Relationships | HunchLab
Business Acquisition [Line Items]
Identifiable technology and intangible assets		$ 160

Business Acquisitions - Compone

Business Acquisitions - Components of Identifiable Technology and Intangible Assets and Estimated Useful Lives (Details) - USD ($) $ in Thousands	Oct. 03, 2018	Dec. 31, 2018
Customer Relationships
Acquired Finite Lived Intangible Assets [Line Items]
Total identifiable technology and intangible assets, Useful Life		7 years
HunchLab
Acquired Finite Lived Intangible Assets [Line Items]
Total identifiable technology and intangible assets, Fair Value	$ 1,110
HunchLab | Software Technology
Acquired Finite Lived Intangible Assets [Line Items]
Total identifiable technology and intangible assets, Fair Value	$ 950
Total identifiable technology and intangible assets, Useful Life	5 years
HunchLab | Customer Relationships
Acquired Finite Lived Intangible Assets [Line Items]
Total identifiable technology and intangible assets, Fair Value	$ 160
Total identifiable technology and intangible assets, Useful Life	7 years

Impairment of Property and Eq_2

Impairment of Property and Equipment - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Impairment of property and equipment	$ 686	$ 793
Puerto Rico and the U S Virgin Islands
Property Plant And Equipment [Line Items]
Impairment of property and equipment		800
Revenues related to contracts		$ 900

Financing Arrangements - Additi

Financing Arrangements - Additional Information (Details)	Mar. 28, 2017Installment$ / sharesshares	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)shares	Dec. 31, 2018USD ($)Business	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 27, 2018USD ($)
Debt Instrument [Line Items]
Weighted average interest rate					11.54%
Interest expense on debt					$ 1,100,000	$ 1,200,000
Amortization of debt issuance costs					132,000	$ 131,000
Net proceeds from Initial public offering excluding underwriting discounts and commissions			$ 32,400,000		$ 32,426,000
The March 28, 2017 Preferred stock warrant | Series B-1 Convertible Preferred Stock
Debt Instrument [Line Items]
Number of shares called by warrant | shares	76,704		61,363
Class of warrant, exercise price | $ / shares	$ 5.8667
2015 Term Note | Other Expense, Net
Debt Instrument [Line Items]
Loss consisting of prepayment fees and miscellaneous fees		$ 200,000
Unamortized debt issuance costs written-off		$ 300,000
Maximum
Debt Instrument [Line Items]
Number of shares called by warrant | shares			84,000
Minimum
Debt Instrument [Line Items]
Net proceeds from Initial public offering excluding underwriting discounts and commissions			$ 25,000,000
Notes Payable | 2015 Term Note
Debt Instrument [Line Items]
Debt instrument maturity date	Oct. 31, 2020
Debt instrument number of periodic payment of principal and interest | Installment	36
Notes Payable | Minimum | 2015 Term Note
Debt Instrument [Line Items]
Debt instrument variable rate	11.00%
LIBOR | Notes Payable | Maximum | 2015 Term Note
Debt Instrument [Line Items]
Debt instrument basis spread	7.50%
LIBOR | Notes Payable | Minimum | 2015 Term Note
Debt Instrument [Line Items]
Debt instrument basis spread	2.50%
Umpqua Credit Agreement
Debt Instrument [Line Items]
Credit facility outstanding amount repayment date				Sep. 27, 2020
Credit facility interest rate description				(1) a base rate, which fluctuates daily and is the greater of (a) the prime rate in effect as of any date of determination and (b) the daily LIBOR rate as of such date of determination plus 1.0% per annum, or (2) a LIBOR rate, which can be for a period of 30, 60 or 90 days at the Company’s option and is equal to the published rate in the Wall Street Journal for such 30-, 60- or 90-day period two business days prior to the commencement of such period, in each case plus 2.0% per annum.
Credit facility covenant description				Under the Umpqua Credit Agreement, the Company is subject to various negative covenants that limit, subject to certain exclusions, the Company’s ability to incur indebtedness, make loans, invest in or secure the obligations of other parties, pay or declare dividends, make distributions with respect to the Company’s securities, redeem outstanding shares of the Company’s stock, create subsidiaries, materially change the nature of its business, enter into related party transactions, engage in mergers and business combinations, the acquisition or transfer of Company assets outside of the ordinary course of business, grant liens or enter into collateral relationships involving company assets or reincorporate, reorganize or dissolve the Company.
Credit facility borrowings outstanding				$ 0
Umpqua Credit Agreement | LIBOR
Debt Instrument [Line Items]
Debt instrument basis spread				2.00%
Period of interest rate option applied on credit facility				30 days
Period of interest rate option applied on credit facility				60 days
Period of interest rate option applied on credit facility				90 days
Number of business days prior to commencement of periods on interest rate | Business				2
Credit facility variable rate				LIBOR
Umpqua Credit Agreement | LIBOR | Fluctuating Rate Per Annum
Debt Instrument [Line Items]
Debt instrument basis spread				1.00%
Revolving Facility | Umpqua Credit Agreement
Debt Instrument [Line Items]
Credit agreement date				Sep. 27, 2018
Credit facility maximum borrowing capacity under loan							$ 10,000,000
Revolving Facility | Umpqua Credit Agreement | Maximum
Debt Instrument [Line Items]
Increase in credit facility total				$ 25,000,000
Letter of Credit Subfacility | Umpqua Credit Agreement
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity under loan							$ 3,000,000

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transactions [Abstract]
Revenue recognized from reseller	$ 0	$ 700,000	$ 200,000

Income Taxes - Schedule of Dome

Income Taxes - Schedule of Domestic and Foreign Components of Net Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Domestic	$ (3,083)	$ (10,125)	$ (6,744)
Foreign	345	305	(116)
Net loss	$ (2,738)	$ (9,820)	$ (6,860)

Income Taxes - Schedule of Prov

Income Taxes - Schedule of Provision for Income Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Current:
Foreign	$ (13)	$ 160
Total	(13)	160
Deferred:
Total tax expense	$ (13)	$ 160

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of Statutory Federal Income Tax Rate to Net Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income tax at statutory rate	$ (575)	$ (3,339)	$ (2,331)
Change in valuation allowance	1,595	(8,354)	2,146
Change in tax rate		9,788
Change in deferreds	7	(39)
State tax	(309)	536	9
Mark-to-market on warrants		1,267	178
Stock-based compensation	(615)	84	24
Research and development credit	(220)	(62)	(88)
Foreign rate differential	(86)	56	40
Subpart F - transition tax	81	68
Lobbying	78	79
Other	31	76	$ 22
Total tax expense	$ (13)	$ 160

Income Taxes - Schedule of Comp

Income Taxes - Schedule of Company's Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Net operating losses	$ 21,461	$ 20,139
Credits	1,969	1,654
Accruals and reserves	285	643
Deferred revenue and contract costs	458	464
Gross deferred tax assets	24,173	22,900
Valuation allowance	(23,710)	(22,789)
Net deferred tax assets	463	111
Deferred tax liabilities:
Fixed assets and intangibles	(545)	$ (111)
Total deferred tax liabilities, net	$ (82)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Increase in valuation allowance	$ 900,000
Unrecognized tax benefits	734,000	$ 620,000	$ 574,000
Interest or penalties accrued	$ 0
Corporate income tax rate	21.00%
Provisional income tax expense (benefit)		$ 9,800,000
Estimated re-measurement of deferred tax asset	$ 9,800,000
California
Income Taxes [Line Items]
Research and experimental credits carryforwards	$ 1,500,000
Research and experimental credits carryforwards, expiration	The California research and experimental tax credits carry forward indefinitely until utilized.
Federal
Income Taxes [Line Items]
Net operating loss carryforwards	$ 85,400,000
Net operating loss carryforward subject to expiration	80,600,000
Net operating loss carryforward not subject to expiration	$ 4,800,000
Net operating loss carryforwards, earliest expiration year	2,026
Net operating loss carryforwards latest expiration year	2,037
Research and experimental credits carryforwards	$ 1,500,000
Research and experimental credits carryforwards, expiration	The federal research and experimental tax credits will begin to expire, if not utilized, in 2026.
State
Income Taxes [Line Items]
Net operating loss carryforwards	$ 54,300,000
Net operating loss carryforwards, earliest expiration year	2,019
Net operating loss carryforwards latest expiration year	2,038

Income Taxes - Schedule of Unre

Income Taxes - Schedule of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ 620	$ 574
Increases for current year tax positions	114	46
Balance at end of year	$ 734	$ 620

Capital Stock - Summary of Outs

Capital Stock - Summary of Outstanding Convertible Preferred Stock (Details) - USD ($) $ in Thousands	May 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Class Of Stock [Line Items]
Temporary equity, aggregate liquidation preference	$ 42,575
Series B-1 Convertible Preferred Stock
Class Of Stock [Line Items]
Temporary equity, shares authorized	4,773,000
Temporary equity, shares issued	3,848,023
Temporary equity, shares outstanding	3,848,023	3,848,023	3,848,023
Temporary equity, aggregate liquidation preference	$ 22,575
Series A-2 Convertible Preferred Stock
Class Of Stock [Line Items]
Temporary equity, shares authorized	1,177,000
Temporary equity, shares issued	1,176,423
Temporary equity, shares outstanding	1,176,423	1,176,423	1,176,423
Temporary equity, aggregate liquidation preference	$ 20,000

Capital Stock - Additional Info

Capital Stock - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017
Class Of Stock [Line Items]
Conversion of preferred stock into common stock, value			$ 42,075,000
Reclassification of convertible preferred stock warrant liability into additional paid-in capital	$ 5,700,000		$ 5,711,000
Preferred stock, shares outstanding		0	0
Common stock, shares authorized		500,000,000	500,000,000
Common stock, par value		$ 0.005	$ 0.005
Common stock, shares issued		10,864,722	9,827,129
Common stock, shares outstanding		10,864,722	9,827,129
Common stock, voting rights		Holders of common stock have voting rights equal to one vote per share of common stock held
Preferred stock, shares authorized		20,000,000	20,000,000
Preferred stock, par value		$ 0.005	$ 0.005
Preferred stock, shares issued		0	0
Convertible Preferred Stock
Class Of Stock [Line Items]
Preferred stock, shares outstanding		0
Common Stock
Class Of Stock [Line Items]
Conversion of preferred stock into common stock, shares	4,689,753		4,689,753
Conversion of preferred stock into common stock, value			$ 23,000
Additional Paid-in Capital
Class Of Stock [Line Items]
Conversion of preferred stock into common stock, value			42,052,000
Reclassification of convertible preferred stock warrant liability into additional paid-in capital	$ 42,100,000		$ 42,100,000

Capital Stock - Schedule of Com

Capital Stock - Schedule of Common Stock Reserved for Future Issuance (Details)	Dec. 31, 2018shares
Class Of Stock [Line Items]
Common stock reserved for future issuance	2,343,087
Options Outstanding
Class Of Stock [Line Items]
Common stock reserved for future issuance	820,186
Shares Available for Future Grant
Class Of Stock [Line Items]
Common stock reserved for future issuance	1,248,424
Unvested Restricted Stock Units
Class Of Stock [Line Items]
Common stock reserved for future issuance	110,764
Warrants to Purchase Common Stock
Class Of Stock [Line Items]
Common stock reserved for future issuance	163,713

Net Loss per Share - Summary of

Net Loss per Share - Summary of Computation of Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Numerator:
Net loss	$ (2,725)	$ (9,980)	$ (6,860)
Denominator:
Weighted-average shares outstanding, basic and diluted	10,569,007	6,197,775	1,602,402
Net loss per share	$ (0.26)	$ (1.61)	$ (4.28)

Net Loss per Share - Schedule o

Net Loss per Share - Schedule of Anti-dilutive Shares Outstanding Excluded in Calculation of Diluted Net Loss per Share (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	1,094,663	1,809,718	6,499,921
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	820,186	1,294,128	1,130,141
Unvested Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	110,764	47,312
The March 2017 Preferred stock warrant or common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	163,713	468,278	680,027
Series B-1 Convertible Preferred Stock (as-converted)
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total			3,848,023
Series A-2 Convertible Preferred Stock (as-converted)
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total			841,730

Convertible Preferred Stock W_3

Convertible Preferred Stock Warrants and Common Stock Warrants - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Mar. 28, 2017
Class Of Warrant Or Right [Line Items]
Loss on remeasurement of convertible preferred stock warrant liability			$ 3,725,000	$ 524,000
Reclassification of convertible preferred stock warrant liability into additional paid-in capital	$ 5,700,000		5,711,000
Net proceeds from Initial public offering excluding underwriting discounts and commissions	32,400,000		$ 32,426,000
Fair value of warrants	$ 300,000			$ 1,875,000
The March 28, 2017 Preferred stock warrant | Series B-1 Convertible Preferred Stock
Class Of Warrant Or Right [Line Items]
Number of shares called by warrant	61,363				76,704
Class of warrant, exercise price					$ 5.8667
Fair value of warrants					$ 111,000
Warrants Not Settleable in Cash
Class Of Warrant Or Right [Line Items]
Conversion of preferred stock into common stock, shares		25,145
Maximum
Class Of Warrant Or Right [Line Items]
Number of shares called by warrant	84,000
Minimum
Class Of Warrant Or Right [Line Items]
Net proceeds from Initial public offering excluding underwriting discounts and commissions	$ 25,000,000
Other Expense, Net
Class Of Warrant Or Right [Line Items]
Loss on remeasurement of convertible preferred stock warrant liability		$ 3,700,000

Convertible Preferred Stock W_4

Convertible Preferred Stock Warrants and Common Stock Warrants - Schedule of Warrants Issued and Outstanding (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Class Of Warrant Or Right [Line Items]
Shares of warrants issued and outstanding		163,713	468,278		680,027
Fair value of warrants issued and outstanding				$ 300	$ 1,875
The June 2012 Series B-1 convertible preferred stock warrant
Class Of Warrant Or Right [Line Items]
Shares of warrants issued and outstanding					25,568
Fair value of warrants issued and outstanding					$ 303
Issuance Date		2012-06
Price per Share		$ 5.8667
Expiration Date		2022-06
The July 2012 Series B-1 convertible preferred stock warrant
Class Of Warrant Or Right [Line Items]
Shares of warrants issued and outstanding					167,428
Fair value of warrants issued and outstanding					$ 263
Issuance Date		2012-07
Price per Share		$ 5.8667
Expiration Date		2019-07
The August 2012 Series B-1 convertible preferred stock warrant
Class Of Warrant Or Right [Line Items]
Shares of warrants issued and outstanding					145,801
Fair value of warrants issued and outstanding					$ 46
Issuance Date		2012-08
Price per Share		$ 5.8667
Expiration Date		2019-08
The November 2012 Series B-1 convertible preferred stock warrant
Class Of Warrant Or Right [Line Items]
Shares of warrants issued and outstanding					10,517
Fair value of warrants issued and outstanding					$ 19
Issuance Date		2012-11
Price per Share		$ 5.8667
Expiration Date		2022-11
The February 2014 Series B-1 convertible preferred stock warrant
Class Of Warrant Or Right [Line Items]
Shares of warrants issued and outstanding					156,851
Fair value of warrants issued and outstanding					$ 929
Issuance Date		2014-02
Price per Share		$ 0.1700
Expiration Date		2021-02
The September 2015 Series B-1 convertible preferred stock warrant
Class Of Warrant Or Right [Line Items]
Shares of warrants issued and outstanding					173,862
Fair value of warrants issued and outstanding					$ 315
Issuance Date		2015-09
Price per Share		$ 5.8667
Expiration Date		2025-09
The July 2012 Common stock warrant
Class Of Warrant Or Right [Line Items]
Shares of warrants issued and outstanding		3,766	165,925
Issuance Date		2012-07
Price per Share		$ 5.8667
Expiration Date		2019-07
The August 2012 Common stock warrant
Class Of Warrant Or Right [Line Items]
Shares of warrants issued and outstanding		25,231	61,502
Issuance Date		2012-08
Price per Share		$ 5.8667
Expiration Date		2019-08
The February 2014 Common stock warrant
Class Of Warrant Or Right [Line Items]
Shares of warrants issued and outstanding		50,716	156,851
Issuance Date		2014-02
Price per Share		$ 0.1700
Expiration Date		2021-02
The June 2017 Common stock warrant
Class Of Warrant Or Right [Line Items]
Shares of warrants issued and outstanding	[1]	84,000	84,000
Issuance Date	[1]	2017-06
Price per Share	[1]	$ 13.2000
Expiration Date	[1]	2020-06
[1]	This warrant was issued to the Company’s lead underwriter in connection with the IPO.

Equity Incentive Plans - Additi

Equity Incentive Plans - Additional Information (Details)	Jan. 01, 2018shares	May 31, 2017shares	Dec. 31, 2018USD ($)Participant$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance			2,343,087
Unvested options resulting from early exercises			0	0	0
Aggregate intrinsic value of options exercised | $			$ 12,600,000	$ 800,000	$ 23,000,000,000
Total intrinsic value of all outstanding options | $			19,300,000	15,900,000	2,500,000
Total unrecognized stock-based compensation cost related to unvested stock options | $			$ 3,300,000	$ 800,000
Total unrecognized stock-based compensation cost related to unvested stock options, recognized ratably over a weighted-average period			3 years 3 months 18 days	3 years 2 months 12 days
Cash received from exercise of stock options | $			$ 550,000	$ 55,000	$ 25,000
Income tax benefits from stock-based compensation | $			$ 0
Restricted Stock Unit
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period			12 months
Total unrecognized stock-based compensation cost related to unvested stock options, recognized ratably over a weighted-average period			2 years 8 months 12 days	4 months 24 days
Number of Units, Granted			92,883
Grant Date Fair Value, Granted | $ / shares			$ 17.87
Total unrecognized stock-based compensation cost related RSUs | $			$ 1,400,000	$ 300,000
Restricted Stock Unit | Vesting Rate, Year One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Granted restricted stock units of common stock, vesting percentage			35.00%
Restricted Stock Unit | Vesting Rate, Year Two
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Granted restricted stock units of common stock, vesting percentage			21.667%
Restricted Stock Unit | Vesting Rate, Year Three
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Granted restricted stock units of common stock, vesting percentage			21.667%
Restricted Stock Unit | Vesting Rate, Year Four
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Granted restricted stock units of common stock, vesting percentage			21.667%
Restricted Stock Unit | Director
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Units, Granted			17,881	47,312
Grant Date Fair Value, Granted | $ / shares			$ 28.45
Minimum | Restricted Stock Unit
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period				7 years
Minimum | Restricted Stock Unit | Director
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Grant Date Fair Value, Granted | $ / shares				$ 11.50
Maximum | Restricted Stock Unit
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period				10 months
Maximum | Restricted Stock Unit | Director
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Grant Date Fair Value, Granted | $ / shares				$ 16.96
2017 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance		2,413,659
Number of shares available for future grant		900,000	1,248,424
Shares of common stock reserved for issuance, automatic annual increase initiation date		Jan. 1, 2018
Percentage of number of shares of common stock outstanding				5.00%
Increase in common stock reserved for issuance	491,356
2017 Equity Incentive Plan | Shares under 2005 Plan that would have otherwise been returned to 2005 Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance		1,314,752
Incentive Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Ownership percentage, minimum			10.00%
Incentive Stock Options | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair value of common stock granted to employees			110.00%
2005 Plan and 2017 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period			4 years
2005 Plan and 2017 Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expiration period			10 years
2017 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance			200,000
Number of shares available for future grant			232,262
Percentage of number of shares of common stock outstanding				2.00%
Increase in common stock reserved for issuance	150,000
Percentage of fair market value of common stock on purchase date of the first day of IPO		85.00%
Percentage of fair market value of common stock on purchase date		85.00%
Purchase of common stock under ESPP, Description			The 2017 ESPP allows eligible employees to purchase shares of the Company’s common stock in an offering at a discount of the then-current trading price, up to the lesser of (1) 85% of the fair market value of the common stock on the first day of the IPO or (2) 85% of the fair market value of the common stock on the purchase date. The 2017 ESPP permits the maximum discounted purchase price permitted under U.S. tax rules, including a “lookback.”
Initial offering period in length			24 months
Number of participant have the right to purchase shares of common stock | Participant			0
Fair Market Value Of Common Stock | $			$ 25,000
Periodic increment of common stock reserved for future issuance			150,000
Shares issued under ESPP			83,605

Equity Incentive Plans - Schedu

Equity Incentive Plans - Schedule of Fair Value of Stock Option Grants Valuation Assumptions by Block-Scholes Option Pricing Model (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years
Expected volatility		55.00%	55.00%
Expected dividend yield	0.00%
Risk-free interest rate, minimum	2.60%	1.85%	0.75%
Risk-free interest rate, maximum	3.00%	2.29%	1.77%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of common stock	$ 23.72	$ 3.06	$ 0.85
Expected term (in years)		5 years	2 years
Expected volatility	64.00%
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of common stock	$ 47.39	$ 19.56	$ 3.06
Expected term (in years)		6 years	10 years
Expected volatility	67.00%

Equity Incentive Plans - Sche_2

Equity Incentive Plans - Schedule of Stock Option Activity (Details) - 2005 Plan and 2017 Plan - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of Options Outstanding, Beginning Balance	1,294,128	1,130,141	938,250
Number of Options Outstanding, Granted	157,078	261,476	272,769
Number of Options Outstanding, Exercised	(609,985)	(74,984)	(33,395)
Number of Options Outstanding, Canceled	(21,035)	(22,505)	(47,483)
Number of Options Outstanding, Ending Balance	820,186	1,294,128	1,130,141
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Price, Beginning Balance	$ 1.79	$ 0.86	$ 0.90
Weighted Average Exercise Price, Granted	33.70	5.52	1.27
Weighted Average Exercise Price, Exercised	0.90	0.74	0.75
Weighted Average Exercise Price, Canceled	6.78	1.52	4.14
Weighted Average Exercise Price, Ending Balance	$ 8.44	$ 1.79	$ 0.86

Equity Incentive Plans - Sche_3

Equity Incentive Plans - Schedule of Stock Options Outstanding, Exercisable and Vested (Details) - 2005 Plan and 2017 Plan - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding balance	820,186	1,294,128	1,130,141	938,250
Weighted-average Remaining Contractual Life (years)	7 years 2 months 1 day	6 years 2 months 19 days	6 years 3 months 14 days
Exercisable and Vested balance	439,927	883,959	842,261
Weighted-average Remaining Contractual Life (years)	5 years 11 months 26 days	5 years	5 years 3 months 25 days
Weighted-average Exercise Price	$ 1.66	$ 0.85	$ 0.74

Equity Incentive Plans - Sche_4

Equity Incentive Plans - Schedule of Stock-Based Compensation Expense Recorded in Consolidated Statements of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 2,468	$ 628	$ 83
Costs
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	316	75	11
Sale and Marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	770	133	7
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	272	69	18
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,110	$ 351	$ 47

Benefit Plan - Additional Infor

Benefit Plan - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
401(k) Plan
Defined Contribution Plan Disclosure [Line Items]
Company contributions to plan	$ 0	$ 0	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Non-cancelable operating lease expiration period	2,021
Total rent expense	$ 0.6	$ 0.4	$ 0.4
Lawsuit filing date	November 6, 2017
Description of settlement	On October 4, 2018, the parties reached a binding settlement. The Contractors filed a Notice of Unconditional Settlement on October 9, 2018, which gives them 45 days from October 4, 2018 to file a request for dismissal. The Contractors filed a request for dismissal on October 24, 2018 and such dismissal was entered as requested on October 24, 2018

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Future Minimum Data Center Arrangements and Lease Payments Under Non-cancelable Commitments (Details) $ in Thousands	Dec. 31, 2018USD ($)
Data Center Arrangements
2,019	$ 213
2,020	71
Total	284
Operating Leases
2,019	352
2,020	357
2,021	304
Total	$ 1,013