ShotSpotter (SSTI) 10-K 28 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Mar. 21, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
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	Non-accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		10,312,702
Entity Public Float			$ 63,340,096

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 19,567	$ 3,865
Accounts receivable	3,928	2,410
Prepaid expenses and other current assets	839	567
Restricted cash	30	30
Total current assets	24,364	6,872
Property and equipment, net	11,596	8,959
Intangible assets, net	95	66
Other assets	143	220
Total assets	36,198	16,117
Current liabilities
Accounts payable	1,627	1,336
Deferred revenue, short-term	15,780	10,863
Accrued expenses and other current liabilities	3,815	2,359
Notes payable, net of current maturities		667
Total current liabilities	21,222	15,225
Notes payable, net of current maturities and unamortized debt issuance costs		11,012
Convertible preferred stock warrant liability		1,875
Deferred revenue, long-term	2,710	3,112
Other liabilities	104	24
Total liabilities	24,036	31,248
Commitments and contingencies (Note 16)
Stockholders' (deficit) equity:
Preferred stock: $0.005 par value; 20,000,000 shares authorized; no shares issued and outstanding as of December 31, 2016 and 2017
Common stock: $0.005 par value; 8,000,000 and 500,000,000 shares authorized; 1,616,996 and 9,827,129 shares issued and outstanding as of December 31, 2016 and 2017, respectively	48	8
Additional paid-in capital	109,708	30,403
Accumulated deficit	(97,595)	(87,615)
Accumulated other comprehensive income (loss)	1	(2)
Total stockholders' (deficit) equity	12,162	(57,206)
Total liabilities and stockholders' (deficit) equity	$ 36,198	16,117
Series B-1 Convertible Preferred Stock
Current liabilities
Preferred stock		22,075
Series A-2 Convertible Preferred Stock
Current liabilities
Preferred stock		$ 20,000

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
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	8,000,000
Common stock, shares issued	9,827,129	1,616,996
Common stock, shares outstanding	9,827,129	1,616,996
Series B-1 Convertible Preferred Stock
Convertible preferred stock, par value	$ 0.005	$ 0.005
Convertible preferred stock, shares authorized	4,773,000	4,773,000
Convertible preferred stock, shares issued	0	3,848,023
Convertible preferred stock, shares outstanding	0	3,848,023
Convertible preferred stock, liquidation preference		$ 22,575
Series A-2 Convertible Preferred Stock
Convertible preferred stock, par value	$ 0.005	$ 0.005
Convertible preferred stock, shares authorized	1,177,000	1,177,000
Convertible preferred stock, shares issued	0	1,176,423
Convertible preferred stock, shares outstanding	0	1,176,423
Convertible preferred stock, liquidation preference		$ 20,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenues	$ 23,763	$ 15,507	$ 11,791
Costs
Cost of revenues	11,370	9,549	8,304
Impairment of property and equipment	793
Total costs	12,163	9,549	8,304
Gross profit	11,600	5,958	3,487
Operating expenses
Sales and marketing	6,179	4,475	3,841
Research and development	4,159	4,093	3,359
General and administrative	5,595	2,362	1,807
Total operating expenses	15,933	10,930	9,007
Operating loss	(4,333)	(4,972)	(5,520)
Other expense, net
Remeasurement of convertible preferred stock warrant liability	(3,725)	(524)
Loss on early extinguishment of debt	(479)		(77)
Interest expense, net	(1,114)	(1,317)	(643)
Other expense, net	(169)	(47)	(28)
Total other expense, net	(5,487)	(1,888)	(671)
Loss before income taxes	(9,820)	(6,860)	(6,191)
Provision for income taxes	160
Net loss	$ (9,980)	$ (6,860)	$ (6,191)
Net loss per share, basic and diluted	$ (1.61)	$ (4.28)	$ (3.99)
Weighted average shares used in computing net loss per share, basic and diluted	6,197,775	1,602,402	1,552,780

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (9,980)	$ (6,860)	$ (6,191)
Other comprehensive income (loss):
Change in foreign currency translation adjustment	3	(2)
Comprehensive loss	$ (9,977)	$ (6,862)	$ (6,191)

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity/(Deficit) - USD ($) $ in Thousands	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, 2014	$ (44,429)			$ 8	$ 30,127	$ (74,564)
Temporary equity, Begining balance, Shares at Dec. 31, 2014		3,507,117	1,176,423
Temporary equity, Beginning balance at Dec. 31, 2014		$ 20,081	$ 20,000
Beginning balance, Shares at Dec. 31, 2014				1,538,402
Issuance of Series B-1 convertible preferred stock, net of issuance costs of $6		$ 1,994
Issuance of Series B-1 convertible preferred stock, Shares		340,906
Exercise of stock options	31				31
Exercise of stock options, Shares				45,199
Stock-based compensation	137				137
Net loss	(6,191)					(6,191)
Ending balance at Dec. 31, 2015	(50,452)			$ 8	30,295	(80,755)
Temporary equity, Ending balance, Shares at Dec. 31, 2015		3,848,023	1,176,423
Temporary equity, Ending balance at Dec. 31, 2015		$ 22,075	$ 20,000
Ending balance, Shares at Dec. 31, 2015				1,583,601
Exercise of stock options	25				25
Exercise of stock options, Shares				33,395
Stock-based compensation	83				83
Other comprehensive (loss) income	(2)						$ (2)
Net loss	(6,860)					(6,860)
Ending balance at Dec. 31, 2016	(57,206)			$ 8	30,403	(87,615)	(2)
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	$ 20,000
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			$ 16	32,410
Issuance of common stock upon IPO, Shares				3,220,000
IPO costs	(1,870)				(1,870)
Conversion of convertible preferred stock of common stock upon IPO	42,075			$ 23	42,052
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)	$ (20,000)
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				5,711
Exercise of stock options	55				55
Exercise of stock options, Shares				74,984
Issuance of common stock in connection with cashless exercise of warrants	1			$ 1
Issuance of common stock in connection with cashless exercise of warrants, Shares				191,263
Issuance of common stock from ESPP purchase	319				319
Issuance of common stock from ESPP purchase, Shares				34,133
Stock-based compensation	628				628
Other comprehensive (loss) income	3						3
Net loss	(9,980)					(9,980)
Ending balance at Dec. 31, 2017	$ 12,162			$ 48	$ 109,708	$ (97,595)	$ 1
Temporary equity, Ending balance, Shares at Dec. 31, 2017		0	0
Ending balance, Shares at Dec. 31, 2017				9,827,129

Consolidated Statements of Con7

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity/(Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2015
Underwriting commissions and discounts	$ 3,000
Series B-1 Convertible Preferred Stock
Temporary equity issuance costs		$ 6

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net loss	$ (9,980,000)	$ (6,860,000)	$ (6,191,000)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	3,121,000	2,551,000	2,264,000
Impairment of property and equipment	793,000
Stock-based compensation	628,000	83,000	137,000
Amortization of debt issuance costs	132,000	131,000	88,000
Remeasurement of convertible preferred stock warrant liability	3,725,000	524,000
Loss on early extinguishment of debt	479,000		77,000
Loss on disposal of property and equipment		27,000	30,000
Changes in operating assets and liabilities:
Accounts receivable	(1,518,000)	255,000	(1,845,000)
Prepaid expenses and other assets	(247,000)	(90,000)	(115,000)
Accounts payable	291,000	410,000	69,000
Accrued expenses and other current liabilities	1,535,000	1,049,000	334,000
Deferred revenue	4,428,000	4,177,000	1,649,000
Net cash provided by (used in) operating activities	3,387,000	2,257,000	(3,503,000)
Cash flows from investing activities:
Purchase of property and equipment	(6,430,000)	(4,476,000)	(2,155,000)
Investment in intangible and other assets	(76,000)	(78,000)	(25,000)
Net cash used in investing activities	(6,506,000)	(4,554,000)	(2,180,000)
Cash flows from financing activities:
Proceeds from initial public offering, net of commissions and discounts	32,426,000
Proceeds from line of credit			1,900,000
Proceeds from notes payable	1,500,000	2,000,000	10,000,000
Repayment of notes payable	(13,500,000)		(3,060,000)
Payment of debt issuance costs	(30,000)	(17,000)	(319,000)
Payment on debt extinguishment costs	(149,000)
Proceeds from issuance of Series B-1 convertible preferred stock, net of issuance costs			1,994,000
Repayment of line of credit			(1,900,000)
Payments of initial public offering costs	(1,870,000)
Proceeds from exercise of stock options	55,000	25,000	31,000
Proceeds from ESPP	319,000
Net cash provided by financing activities	18,751,000	2,008,000	8,646,000
Increase in cash and cash equivalents	15,632,000	(289,000)	2,963,000
Effect of exchange rate on cash and cash equivalents	70,000	30,000
Cash and cash equivalents at beginning of year	3,865,000	4,124,000	1,161,000
Cash and cash equivalents at end of period	19,567,000	3,865,000	4,124,000
Supplemental cash flow disclosures:
Cash paid for interest	1,235,000	$ 1,186,000	374,000
Supplemental disclosure of non-cash financing activities:
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
Issuance of warrants in connection with the issuance of notes payable	$ 111,000		$ 147,000

Organization and Description of

Organization and Description of Business	12 Months Ended
	Dec. 31, 2017
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 gunshot detection solutions that help law enforcement officials and security personnel identify, locate and deter gun violence. The Company offers its software 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, 2017
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 13, Convertible Preferred Stock Warrants and Common Stock 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, 2017
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 2017. 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 lives of tangible and intangible assets, 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 Through the year ended December 31, 2017 the Company recognized revenue in accordance with Accounting Standard Codification (“ASC”) 605, Revenue Recognition, and, accordingly, when all of the following criteria were met. • Persuasive evidence of an arrangement exists • Delivery has occurred or services have been rendered • The sales price is fixed or determinable • Collection of the related receivable is reasonably assured 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 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. Therefore, these service arrangements are accounted for as subscriptions. 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. Each type of revenue was recognized as follows: Subscription Revenues — The Company recognized subscription revenues ratably over the subscription period committed by the customer and commencing when the subscription service is 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. Revenues from Setup Fees — 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 considers 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 . The Company generally invoices its customers for 50% of the total contract price at the time the contract is signed, and for the remaining 50% of the total contract price when the subscription service is operational and ready to go live. The terms of the Company’s service agreements contain multiple deliverables, which include the subscription service and setup services, as described above. The Company evaluates its multiple-element arrangements to determine (i) the deliverables included in the arrangement and (ii) whether the individual deliverables represent separate units of accounting or whether they must be accounted for as a combined unit of accounting. Deliverables are considered separate units of accounting provided that (1) the delivered item has standalone value to the customer; and (2) if the arrangement includes a general right of return with respect to the delivered item, delivery or performance of the undelivered item is considered probable and substantially in the Company’s control. The Company allocates revenue to each element in an arrangement based on a selling price hierarchy. The selling price for a deliverable is based on its estimated selling price, as neither vendor specific objective evidence nor third party evidence of selling price is available. Any discount is allocated proportionally to all deliverables in the arrangement. The Company has concluded that the setup services do not have stand-alone value to customers since the Company has not historically sold these services separately. In addition, these services have no value to the customer in the absence of the subscription service sold by the Company. Accordingly, the Company does not present revenues from setup fees separately on the consolidated statements of operations. If a customer renews its subscription after the expiration of the previous subscription term, the Company only recognized revenue for a renewal upon receipt of a signed contract from the customer, which could be several months following expiration of the original contract. The term of the renewed subscription starts on the original expiration date, as service is generally not discontinued upon the expiration of a contract if the contract is expected to be renewed. The Company recognized revenue for the elapsed term in the month in which the renewal contract is executed. Starting on January 1, 2018, the Company will recognize revenue in accordance with ASC Topic 606, Revenue from Contracts with Customers. Deferred Revenue Deferred revenue consists substantially of amounts billed, or payments received in advance of revenue recognition, as described above. Once all revenue recognition criteria have been met, the deferred revenue is recognized. The short-term portion of deferred revenue represents the unearned revenues that has been collected in advance that will be recognized within 12 months of the balance sheet date. Correspondingly, long-term deferred revenue represents the unearned revenues that will be earned and recognized after 12 months from the balance sheet date. Costs of Revenue 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 $0.3 million for the year ended December 31, 2015 and $0.5 million for the both of the years ended December 31, 2016 and 2017, 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, 2016 and 2017, the Company’s cash and cash equivalents consisted of cash deposited in financial institutions. Restricted Cash At December 31, 2016 and 2017, restricted cash consisted of certificates of deposit held at a financial institution as collateral for credit cards held by the Company. Foreign Currency Translation 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 Accounts receivable 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. 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, 2016 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 two domestic 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, 2016, three customers accounted for 27%, 16% and 11% 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, 2015, no single customer accounted for 10% or more of the Company’s revenues. For the year ended December 31, 2016 two customers each accounted for 12% of the Company’s revenues. For the year ended December 31, 2017, one customer accounted for 18% 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. Intangible Assets Intangible assets consisted of acquired patents and capitalized legal fees related to obtaining patents. Intangible assets are carried at cost, less accumulated amortization. Amortization is computed on a straight-line basis over three years, the estimated useful life of the assets. 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, which is five years. 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. The Company has not recorded any impairment of long-lived assets through December 31, 2016. 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. 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 2015, 2016 and 2017, 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, $35,000 and $60,000 for the years ended December 31, 2015, 2016 and 2017, respectively. Capitalized Internal-Use Software Costs incurred to develop software for internal use and for the Company’s solutions are capitalized and amortized over such software’s estimated useful life. Costs capitalized during all periods presented have not been material. Other Comprehensive Income (Loss) Other comprehensive income (loss) is generally gains or losses associated with fluctuations in currency exchange rates for revenues and expenses paid in foreign currency. For the year ended December 31, 2015, the Company did not have any other comprehensive income or loss and, therefore, net loss and comprehensive loss were the same for this period. For the years ended December 31, 2016 and 2017, other comprehensive income (loss) consisted of foreign currency translation adjustments related to the Company’s foreign operations. 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’ deficit, 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, 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. 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. 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 In March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-09, Improvements to Employee Share-Based Payment Accounting Recent Accounting Pronouncements Not Yet Effective In May 2014, the FASB issued ASC Topic 606, Revenue from Contracts with Customers The Company has historically recognized revenue related to setup fees, including training and license to integrate with third-party applications, ratably over five years. Under the new standard, revenue allocable to training and licenses to integrate will be recognized upon delivery and the remaining setup fees will be recognized over three years. The new standard will also impact our determination of standalone selling prices, which will impact the allocation of transaction price to each performance obligation, thereby impacting the timing of revenue recognition depending on when each performance obligation is recognized. The new standard also requires the capitalization of certain incremental costs of obtaining a contract, which will impact the period in which the Company records sales commissions expense. The Company has historically recognized sales commissions expense upfront. Under the new standard, the Company is required to recognize these expenses consistently with the transfer of goods or services. This will result in a deferral of some sales commission costs. The Company will amortize these deferred costs on a straight-line basis over five years. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) 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 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, 2017
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, 2017. The changes in the fair value of the convertible preferred stock warrant liability are summarized below (in thousands): Fair Value Measurements at Reporting Date Using Level III Inputs Fair value at December 31, 2014 $ 1,204 Issuance of convertible preferred stock warrants 147 Change in fair value recorded in other expense, net — 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 $ —

Intangible Assets, Net

Intangible Assets, Net	12 Months Ended
	Dec. 31, 2017
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, 2016 Gross Accumulated Amortization Net Patents $ 873 $ (807 ) $ 66 December 31, 2017 Gross Accumulated Amortization Net Patents $ 949 $ (854 ) $ 95 Amortization expense during the years ended December 31, 2015, 2016 and 2017 was $86,000, $37,000 and $47,000, respectively.

Details of Certain Consolidated

Details of Certain Consolidated Balance Sheet Accounts	12 Months Ended
	Dec. 31, 2017
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, 2016 2017 Prepaid software and licenses $ 286 $ 407 Prepaid insurance 25 211 Other prepaid expenses 171 137 Other 85 84 $ 567 $ 839 Property and equipment, net (in thousands): December 31, 2016 2017 Deployed equipment $ 13,240 $ 17,091 Computer equipment 912 1,123 Software 202 312 Furniture and fixtures 151 165 Leasehold improvements 185 202 Construction in progress 2,084 1,456 $ 16,774 $ 20,349 Accumulated depreciation and amortization (7,815 ) (8,753 ) $ 8,959 $ 11,596 Accrued expenses and other current liabilities (in thousands): December 31, 2016 2017 Payroll liabilities $ 1,146 $ 1,697 Accrued employee paid time off 372 469 Accrued commissions 51 199 Accrued ESPP — 115 Accrued interest 123 — Royalties payable 225 125 Professional fees 76 328 Sales/ use tax payable 167 406 Other 199 476 $ 2,359 $ 3,815

Impairment of Property and Equi

Impairment of Property and Equipment	12 Months Ended
	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Impairment of Property and Equipment	Note 7. Impairment of Property and Equipment 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, 2017
Debt Disclosure [Abstract]
Financing Arrangements	Note 8. Financing Arrangements Notes Payable 2014 Term Note — In November 2014, the Company entered into a loan and security agreement with a commercial bank which allowed for borrowings up to $3.0 million under a term note (“2014 Term Note”) and up to $7.0 million less the then-current outstanding borrowings under the 2014 Term Note under a line of credit (“2014 Line of Credit”). In November 2014, the Company borrowed $3.0 million under the 2014 Term Note of which $1.8 million of the proceeds was used to repay an outstanding debt with a different commercial bank. Borrowings under the 2014 Term Note bore 5.75% interest (prime rate of 3.25% plus 2.5%), with interest only payments through October 2015, followed by 24 equal monthly installments of principal and interest. The Company was also required to pay origination fees of $15,000, facilities fees of $70,000 and a termination fee of $60,000. These debt issuance costs were recorded as a direct deduction from notes payable in the consolidated balance sheets and were amortized to interest expense over the term of the note using the effective interest method. In 2015, the Company recognized $55,000 of interest expense in connection with the aforementioned fees. In September 2015, the Company repaid the 2014 Term Note and there was no outstanding balance under the 2014 Term Note at December 31, 2016 and 2017. The write-off of unamortized debt issuance costs of $77,000 was recorded as early extinguishment of debt in general and administrative expenses during the year ended December 31, 2015. 2014 Line of Credit — In February 2015, the Company borrowed $1.0 million, and in May 2015, the Company borrowed an additional $0.9 million, under the 2014 Line of Credit. Outstanding borrowings under the 2014 Line of Credit bore 4.75% interest (prime rate of 3.25% plus 1.5%). In September 2015, the outstanding balance of $1.9 million was repaid in full. 2015 Term Note — At December 31, 2016, the Company had outstanding borrowings under a term note (the “2015 Term Note”) of $11.7 million, net of unamortized debt issuance costs. There were no outstanding borrowings as of December 31, 2017. 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 years ended December 31, 2016 and 2017 was 11.00% and 11.54%, respectively. For the years ended December 31, 2016 and 2017, the Company recognized interest expense of $1.2 million and $1.1 million, respectively, based on the outstanding balance during the respective periods. During the years ended December 31, 2016 and 2017, amortization of debt issuance costs was $131,000 and $132,000, 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. Notes payable consisted of the following (in thousands): December 31, 2017 2016 2017 Notes payable $ 12,000 $ — Unamortized debt issuance costs (321 ) — Current maturities of term note (667 ) — Total notes payable, net of current maturities $ 11,012 $ — Early Extinguishment of Debt 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, 2017
Related Party Transactions [Abstract]
Related Party Transactions	Note 9. Related Party Transactions During the years ended December 31, 2015, 2016 and 2017, the Company recognized approximately $200,000, $200,000, and $700,000 in revenue, respectively from a reseller who is also an investor. As of December 31, 2016, and 2017, the amount of accounts receivable due from this reseller was immaterial.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Income Taxes	Note 10. Income Taxes The domestic and foreign components of net loss were as follows (in thousands): Year Ended December 31, 2015 2016 2017 Domestic $ (6,191 ) $ (6,744 ) $ (10,125 ) Foreign — (116 ) 305 Net Loss $ (6,191 ) $ (6,860 ) $ (9,820 ) 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, 2015 2016 2017 Income tax at statutory rate $ (2,104 ) $ (2,331 ) $ (3,339 ) Change in valuation allowance 3,137 2,146 (8,354 ) Change in tax rate — — 9,788 Change in deferreds (852 ) — (39 ) State tax (184 ) 9 536 Mark-to-market on warrants — 178 1,267 Other 3 (2 ) 301 Total $ — $ — $ 160 Temporary differences that gave rise to significant portions of the Company’s deferred tax assets and liabilities as of December 31, 2016 and 2017 were as follows (in thousands): Year Ended December 31, 2016 2017 Deferred tax assets: Net operating losses $ 28,677 20,139 Credits 1,414 1,654 Accruals and reserves 519 643 Deferred revenue and contract costs 871 464 Gross deferred tax assets 31,481 22,900 Valuation allowance (31,143 ) (22,789 ) Net deferred tax assets 338 111 Deferred tax liabilities: Fixed assets and intangibles (338 ) (111 ) Total deferred tax liabilities, net $ — $ — 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 decreased by $8.4 million during the year ended December 31, 2017. As of December 31, 2017, the Company had total net operating loss carryforwards for federal and state income tax purposes of approximately $80.2 million and $50.8 million, respectively, available to reduce future income subject to income taxes. The federal and state net operating loss carryforwards will begin to expire, if not utilized, in 2018 through 2036. As of December 31, 2017, the Company had available for carryover research and experimental credits for federal and California income tax purposes of approximately $1.2 million and $1.3 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 $0.6 million as of December 31, 2017, all of which was offset by a full valuation allowance. No interest or penalties have been accrued as of December 31, 2017. A reconciliation of the beginning and ending amounts of unrecognized tax benefits is as follows (in thousands): Balance as of December 31, 2015 $ 813 Increases for current year tax positions 63 Increases for prior year tax positions (302 ) 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 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 “Tax 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 are expected over the next 12 months, we consider the accounting of the transition tax and deferred tax re-measurements to be incomplete. Additional work will be necessary for a more detailed analysis of our deferred tax assets and liabilities and our historical foreign earnings as well as potential correlative adjustments. We expect to complete our analysis within the measurement period in accordance with SAB 118. We do not expect any material subsequent adjustment to these amounts. Adjustment if any will have no impact to the income statement due to the Company’s loss position and valuation allowance.

Capital Stock

Capital Stock	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Capital Stock	Note 11. 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, 2017, there were no shares of convertible preferred stock outstanding. Common Stock At December 31, 2016 and December 31, 2017, the Company was authorized to issue 8,000,000 and 500,000,000 shares, respectively, of common stock with a par value of $0.005 per share. At December 31, 2016 and 2017, there were 1,616,996 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, 2016, shares of common stock reserved for future issuance were as follows: December 31, 2016 Conversion of Series B-1 convertible preferred stock 3,848,023 Conversion of Series A-2 convertible preferred stock(1) 841,730 Conversion of Series B-1 convertible preferred stock warrants 680,027 Total conversion of convertible preferred stock and warrants 5,369,780 Options outstanding 1,130,141 Shares available for future grant 390,164 Total 6,890,085 (1) Reflects the effect of an amendment and restatement of the Company’s amended and restated certificate of incorporation in March 2017 to implement a conversion feature for the Series A-2 convertible preferred stock. At December 31, 2017, shares of common stock reserved for future issuance were as follows: December 31, 2017 Options outstanding 1,294,128 Shares available for future grant 1,003,875 Unvested restricted stock units 47,312 Warrants to purchase common stock 468,278 Total 2,813,593 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, 2017, there were no shares of preferred stock issued and outstanding.

Net Loss per Share

Net Loss per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Net Loss per Share	Note 12. 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, 2015 2016 2017 Numerator: Net loss $ (6,191 ) $ (6,860 ) $ (9,980 ) Denominator: Weighted-average shares outstanding, basic and diluted 1,552,780 1,602,402 6,197,775 Net loss per share $ (3.99 ) $ (4.28 ) $ (1.61 ) 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, 2015 2016 2017 Options to purchase common stock 938,250 1,130,141 1,294,128 Unvested restricted stock units — — 47,312 Warrants to purchase Series B-1 convertible preferred or common stock 680,027 680,027 468,278 Series B-1 convertible preferred stock (as-converted) 3,848,023 3,848,023 — Series A-2 convertible preferred stock (as-converted) 841,730 841,730 — Total 6,308,030 6,499,921 1,809,718

Convertible Preferred Stock War

Convertible Preferred Stock Warrants and Common Stock Warrants	12 Months Ended
	Dec. 31, 2017
Warrants And Rights Note Disclosure [Abstract]
Convertible Preferred Stock Warrants and Common Stock Warrants	Note 13. 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, 2017, certain warrants were exercised on a cashless basis and converted into 191,263 shares of common stock. At December 31, 2015 and 2016, the Company had the following Series B-1 convertible preferred stock warrants issued and outstanding (in thousands, except share and per share data): Shares Fair Value Warrant Class 2015 2016 2015 2016 Issuance Date Price per Share Expiration Date Series B-1 25,568 25,568 $ 142 $ 303 June 2012 $ 5.8667 June 2022 Series B-1 167,428 167,428 $ 124 $ 263 July 2012 $ 5.8667 July 2019 Series B-1 145,801 145,801 $ 22 $ 46 August 2012 $ 5.8667 August 2019 Series B-1 10,517 10,517 $ 9 $ 19 November 2012 $ 5.8667 November 2022 Series B-1 156,851 156,851 $ 907 $ 929 February 2014 $ 0.1700 February 2021 Series B-1 173,862 173,862 $ 147 $ 315 September 2015 $ 5.8667 September 2025 Total 680,027 680,027 $ 1,351 $ 1,875 ​ ​ ​ ​ ​ ​ At December 31, 2017, the Company had the following common stock warrants issued and outstanding: Warrant Class Shares Issuance Date Price per Share Expiration Date Common stock warrant 165,925 July 2012 $ 5.8667 July 2019 Common stock warrant 61,502 August 2012 $ 5.8667 August 2019 Common stock warrant 156,851 February 2014 $ 0.1700 February 2021 Common stock warrant (1) 84,000 June 2017 $ 13.2000 June 2020 468,278 (1 ) This warrant was issued to the Company’s lead underwriter in connection with the IPO. In September 2015, in connection with the 2015 Agreement, the Company issued warrants to purchase 173,862 shares of Series B-1 convertible preferred stock. The Company determined the fair value of the warrants on the date of issuance to be $147,000. The warrants were immediately exercisable. In March 28, 2017, in connection with the amendment of the 2015 Term Note (see Note 8 , 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, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Equity Incentive Plans	Note 14. 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 ISOs 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, 2015 and 2016, and 2017, 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 $7,000, $23,000 and $0.8 million during the years ended December 31, 2015, 2016 and 2017, respectively. Based on the fair market value of the Company’s common stock at December 31, 2015, 2016 and 2017, the total intrinsic value of all outstanding options was $0.1 million, $2.5 million and $15.9 million, respectively. At December 31, 2016 and 2017, total unrecognized stock-based compensation cost related to unvested stock options was $0.2 million, and $0.8 million, respectively, which will be recognized ratably over a weighted-average period of 3.2 years and 3.2 years, respectively. Cash received from the exercise of stock options during the years ended December 31, 2015, 2016 and 2017 was $31,000, $25,000 and $55,000, 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, 2015 2016 2017 Fair value of common stock $0.85 $0.85-$3.06 $3.06-$19.56 Expected term (in years) 2-10 2-10 5-6 Risk-free interest rate 0.75%-2.10% 0.75%-1.77% 1.85%-2.29% Expected volatility 55% 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 the year ended December 31, 2017 is as follows: Number of Options Outstanding Weighted Average Exercise Price Outstanding at December 31, 2014 916,584 $ 0.89 Granted 112,068 $ 0.85 Exercised (45,199 ) $ 0.70 Canceled (45,203 ) $ 0.80 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 (74,990 ) $ 0.74 Canceled (22,499 ) $ 1.52 Outstanding at December 31, 2017 1,294,128 $ 1.79 Stock options outstanding, exercisable and vested were as follows: Outstanding at December 31, 2015 Weighted-average Remaining Contractual Life (years) Exercisable and Vested as of December 31, 2015 Weighted-average Remaining Contractual Life (years) Weighted-average Exercise Price 938,250 6.31 731,516 5.79 0.94 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 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 5.00 0.85 During the year ended December 31, 2017, the company granted non-employee directors restricted stock unit (“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. In the second quarter of 2017, our board of directors authorized for issuance 900,000 new shares under our 2017 Plan. 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 1,003,875 as of December 31, 2017. 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 34,133 shares issued and outstanding under the 2017 ESPP during the year ended December 31, 2017. 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, 2015 2016 2017 Costs $ 13 $ 11 $ 75 Sales and marketing 13 7 133 Research and development 32 18 69 General and administrative 79 47 351 Total $ 137 $ 83 $ 628 Stock-based compensation expense is recognized over the award’s expected vesting schedule, adjusted for estimated forfeitures. The Company applied a 0% forfeiture rate for the awards granted during the years ended December 31, 2015, 2016 and 2017. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Forfeitures were estimated based on analysis of the Company’s actual forfeiture experience, employee turnover and other factors.

Benefit Plan

Benefit Plan	12 Months Ended
	Dec. 31, 2017
Compensation And Retirement Disclosure [Abstract]
Benefit Plan	Note 15. 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, 2015, 2016 and 2017.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 16. Commitments and Contingencies Operating Lease 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. Rent expense for the Company’s facilities was $0.3 million for each of the years ended December 31, 2015, 2016 and 2017. The following is a schedule of future minimum lease payments under the non-cancelable operating lease at December 31, 2017 (in thousands): 2018 $ 336 2019 346 2020 357 2021 305 Total $ 1,344 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. The Contractors filed a First Amended Complaint on November 22, 2017, adding four more claims: anticipatory breach of contract, conversion, unjust enrichment, and promissory estoppel. The Contractors then filed an "Amendment to Complaint" on December 8, 2017, which purported to dismiss their section 17200 claim. On March 2, 2018, the Contractors filed and served a Second Amended Complaint, which asserts claims for breach of contract, anticipatory breach of contract, breach of the implied covenant of good faith and fair dealing, and conversion. The claims are all based on the Contractors’ assertion that they were entitled to be granted options to purchase 350,000 shares of our common stock on the basis of a term sheet between us and the Contractors signed in July 2007. The Contractors claim that our subsequent one-for-five and one-for-17 reverse stock splits should not apply to their option awards. On the basis of their allegations, the Contractors have petitioned for “millions of dollars” in damages and other costs and expenses, including attorneys’ fees. We believe that the Contractors’ claims are without merit and are disputing them vigorously. From time to time, we may become in involved in lawsuits as well as subject to various legal proceedings, claims, threats of litigation, and investigations in the ordinary course of business, including claims of alleged infringement of third-party patents and other intellectual property rights, commercial, employment, and other matters. While certain matters to which we are a party may specify the damages claimed, such claims may not represent reasonably possible losses. Given the inherent uncertainties of litigation, the ultimate outcome of these matters cannot be predicted at this time, nor can the amount of possible loss or range of loss, if any, be reasonably estimated. An unfavorable outcome on any litigation matters could require us to pay substantial damages, or, in connection with any intellectual property infringement claims, could require us to pay ongoing royalty payments or could prevent us 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 our business, operating results, financial condition and cash flows.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	Note 17. Subsequent Events For the audited consolidated financial statements, management evaluated subsequent events through March 28, 2018, which is the date these consolidated financial statements were issued.

Basis of Presentation and Sum26

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
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 2017.
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 lives of tangible and intangible assets, 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 Through the year ended December 31, 2017 the Company recognized revenue in accordance with Accounting Standard Codification (“ASC”) 605, Revenue Recognition, and, accordingly, when all of the following criteria were met. • Persuasive evidence of an arrangement exists • Delivery has occurred or services have been rendered • The sales price is fixed or determinable • Collection of the related receivable is reasonably assured 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 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. Therefore, these service arrangements are accounted for as subscriptions. 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. Each type of revenue was recognized as follows: Subscription Revenues — The Company recognized subscription revenues ratably over the subscription period committed by the customer and commencing when the subscription service is 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. Revenues from Setup Fees — 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 considers 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 . The Company generally invoices its customers for 50% of the total contract price at the time the contract is signed, and for the remaining 50% of the total contract price when the subscription service is operational and ready to go live. The terms of the Company’s service agreements contain multiple deliverables, which include the subscription service and setup services, as described above. The Company evaluates its multiple-element arrangements to determine (i) the deliverables included in the arrangement and (ii) whether the individual deliverables represent separate units of accounting or whether they must be accounted for as a combined unit of accounting. Deliverables are considered separate units of accounting provided that (1) the delivered item has standalone value to the customer; and (2) if the arrangement includes a general right of return with respect to the delivered item, delivery or performance of the undelivered item is considered probable and substantially in the Company’s control. The Company allocates revenue to each element in an arrangement based on a selling price hierarchy. The selling price for a deliverable is based on its estimated selling price, as neither vendor specific objective evidence nor third party evidence of selling price is available. Any discount is allocated proportionally to all deliverables in the arrangement. The Company has concluded that the setup services do not have stand-alone value to customers since the Company has not historically sold these services separately. In addition, these services have no value to the customer in the absence of the subscription service sold by the Company. Accordingly, the Company does not present revenues from setup fees separately on the consolidated statements of operations. If a customer renews its subscription after the expiration of the previous subscription term, the Company only recognized revenue for a renewal upon receipt of a signed contract from the customer, which could be several months following expiration of the original contract. The term of the renewed subscription starts on the original expiration date, as service is generally not discontinued upon the expiration of a contract if the contract is expected to be renewed. The Company recognized revenue for the elapsed term in the month in which the renewal contract is executed. Starting on January 1, 2018, the Company will recognize revenue in accordance with ASC Topic 606, Revenue from Contracts with Customers.
Deferred Revenue	Deferred Revenue Deferred revenue consists substantially of amounts billed, or payments received in advance of revenue recognition, as described above. Once all revenue recognition criteria have been met, the deferred revenue is recognized. The short-term portion of deferred revenue represents the unearned revenues that has been collected in advance that will be recognized within 12 months of the balance sheet date. Correspondingly, long-term deferred revenue represents the unearned revenues that will be earned and recognized after 12 months from the balance sheet date.
Costs of Revenue	Costs of Revenue 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 $0.3 million for the year ended December 31, 2015 and $0.5 million for the both of the years ended December 31, 2016 and 2017, 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, 2016 and 2017, the Company’s cash and cash equivalents consisted of cash deposited in financial institutions.
Restricted Cash	Restricted Cash At December 31, 2016 and 2017, restricted cash consisted of certificates of deposit held at a financial institution as collateral for credit cards held by the Company.
Foreign Currency Translation	Foreign Currency Translation 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	Accounts Receivable Accounts receivable 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. 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, 2016 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 two domestic 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, 2016, three customers accounted for 27%, 16% and 11% 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, 2015, no single customer accounted for 10% or more of the Company’s revenues. For the year ended December 31, 2016 two customers each accounted for 12% of the Company’s revenues. For the year ended December 31, 2017, one customer accounted for 18% 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.
Intangible Assets	Intangible Assets Intangible assets consisted of acquired patents and capitalized legal fees related to obtaining patents. Intangible assets are carried at cost, less accumulated amortization. Amortization is computed on a straight-line basis over three years, the estimated useful life of the assets.
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, which is five years.
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. The Company has not recorded any impairment of long-lived assets through December 31, 2016. 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.
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 2015, 2016 and 2017, 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, $35,000 and $60,000 for the years ended December 31, 2015, 2016 and 2017, respectively.
Capitalized Internal-Use Software	Capitalized Internal-Use Software Costs incurred to develop software for internal use and for the Company’s solutions are capitalized and amortized over such software’s estimated useful life. Costs capitalized during all periods presented have not been material.
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) Other comprehensive income (loss) is generally gains or losses associated with fluctuations in currency exchange rates for revenues and expenses paid in foreign currency. For the year ended December 31, 2015, the Company did not have any other comprehensive income or loss and, therefore, net loss and comprehensive loss were the same for this period. For the years ended December 31, 2016 and 2017, other comprehensive income (loss) consisted of foreign currency translation adjustments related to the Company’s foreign operations.
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’ deficit, 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, 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. 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.
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 In March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-09, Improvements to Employee Share-Based Payment Accounting
Recent Accounting Pronouncements Not Yet Effective	Recent Accounting Pronouncements Not Yet Effective In May 2014, the FASB issued ASC Topic 606, Revenue from Contracts with Customers The Company has historically recognized revenue related to setup fees, including training and license to integrate with third-party applications, ratably over five years. Under the new standard, revenue allocable to training and licenses to integrate will be recognized upon delivery and the remaining setup fees will be recognized over three years. The new standard will also impact our determination of standalone selling prices, which will impact the allocation of transaction price to each performance obligation, thereby impacting the timing of revenue recognition depending on when each performance obligation is recognized. The new standard also requires the capitalization of certain incremental costs of obtaining a contract, which will impact the period in which the Company records sales commissions expense. The Company has historically recognized sales commissions expense upfront. Under the new standard, the Company is required to recognize these expenses consistently with the transfer of goods or services. This will result in a deferral of some sales commission costs. The Company will amortize these deferred costs on a straight-line basis over five years. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) 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 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

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Summary of Changes in Fair Value of Convertible Preferred Stock Warrant Liability	The changes in the fair value of the convertible preferred stock warrant liability are summarized below (in thousands): Fair Value Measurements at Reporting Date Using Level III Inputs Fair value at December 31, 2014 $ 1,204 Issuance of convertible preferred stock warrants 147 Change in fair value recorded in other expense, net — 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 $ —

Intangible Assets, Net (Tables)

Intangible Assets, Net (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets Net	Intangible assets, net, consisted of the following (in thousands): December 31, 2016 Gross Accumulated Amortization Net Patents $ 873 $ (807 ) $ 66 December 31, 2017 Gross Accumulated Amortization Net Patents $ 949 $ (854 ) $ 95

Details of Certain Consolidat29

Details of Certain Consolidated Balance Sheet Accounts (Tables)	12 Months Ended
	Dec. 31, 2017
Balance Sheet Related Disclosures [Abstract]
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets (in thousands): December 31, 2016 2017 Prepaid software and licenses $ 286 $ 407 Prepaid insurance 25 211 Other prepaid expenses 171 137 Other 85 84 $ 567 $ 839
Schedule of Property and Equipment, Net	Property and equipment, net (in thousands): December 31, 2016 2017 Deployed equipment $ 13,240 $ 17,091 Computer equipment 912 1,123 Software 202 312 Furniture and fixtures 151 165 Leasehold improvements 185 202 Construction in progress 2,084 1,456 $ 16,774 $ 20,349 Accumulated depreciation and amortization (7,815 ) (8,753 ) $ 8,959 $ 11,596
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities (in thousands): December 31, 2016 2017 Payroll liabilities $ 1,146 $ 1,697 Accrued employee paid time off 372 469 Accrued commissions 51 199 Accrued ESPP — 115 Accrued interest 123 — Royalties payable 225 125 Professional fees 76 328 Sales/ use tax payable 167 406 Other 199 476 $ 2,359 $ 3,815

Financing Agreements (Tables)

Financing Agreements (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of Notes Payable	Notes payable consisted of the following (in thousands): December 31, 2017 2016 2017 Notes payable $ 12,000 $ — Unamortized debt issuance costs (321 ) — Current maturities of term note (667 ) — Total notes payable, net of current maturities $ 11,012 $ —

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2015 2016 2017 Domestic $ (6,191 ) $ (6,744 ) $ (10,125 ) Foreign — (116 ) 305 Net Loss $ (6,191 ) $ (6,860 ) $ (9,820 )
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, 2015 2016 2017 Income tax at statutory rate $ (2,104 ) $ (2,331 ) $ (3,339 ) Change in valuation allowance 3,137 2,146 (8,354 ) Change in tax rate — — 9,788 Change in deferreds (852 ) — (39 ) State tax (184 ) 9 536 Mark-to-market on warrants — 178 1,267 Other 3 (2 ) 301 Total $ — $ — $ 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, 2016 and 2017 were as follows (in thousands): Year Ended December 31, 2016 2017 Deferred tax assets: Net operating losses $ 28,677 20,139 Credits 1,414 1,654 Accruals and reserves 519 643 Deferred revenue and contract costs 871 464 Gross deferred tax assets 31,481 22,900 Valuation allowance (31,143 ) (22,789 ) Net deferred tax assets 338 111 Deferred tax liabilities: Fixed assets and intangibles (338 ) (111 ) Total deferred tax liabilities, net $ — $ —
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, 2015 $ 813 Increases for current year tax positions 63 Increases for prior year tax positions (302 ) 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

Capital Stock (Tables)

Capital Stock (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2016, shares of common stock reserved for future issuance were as follows: December 31, 2016 Conversion of Series B-1 convertible preferred stock 3,848,023 Conversion of Series A-2 convertible preferred stock(1) 841,730 Conversion of Series B-1 convertible preferred stock warrants 680,027 Total conversion of convertible preferred stock and warrants 5,369,780 Options outstanding 1,130,141 Shares available for future grant 390,164 Total 6,890,085 (1) Reflects the effect of an amendment and restatement of the Company’s amended and restated certificate of incorporation in March 2017 to implement a conversion feature for the Series A-2 convertible preferred stock. At December 31, 2017, shares of common stock reserved for future issuance were as follows: December 31, 2017 Options outstanding 1,294,128 Shares available for future grant 1,003,875 Unvested restricted stock units 47,312 Warrants to purchase common stock 468,278 Total 2,813,593

Net Loss per Share (Tables)

Net Loss per Share (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2015 2016 2017 Numerator: Net loss $ (6,191 ) $ (6,860 ) $ (9,980 ) Denominator: Weighted-average shares outstanding, basic and diluted 1,552,780 1,602,402 6,197,775 Net loss per share $ (3.99 ) $ (4.28 ) $ (1.61 )
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, 2015 2016 2017 Options to purchase common stock 938,250 1,130,141 1,294,128 Unvested restricted stock units — — 47,312 Warrants to purchase Series B-1 convertible preferred or common stock 680,027 680,027 468,278 Series B-1 convertible preferred stock (as-converted) 3,848,023 3,848,023 — Series A-2 convertible preferred stock (as-converted) 841,730 841,730 — Total 6,308,030 6,499,921 1,809,718

Convertible Preferred Stock W34

Convertible Preferred Stock Warrants and Common Stock Warrants (Tables)	12 Months Ended
	Dec. 31, 2017
Warrants And Rights Note Disclosure [Abstract]
Schedule of Warrants Issued and Outstanding	At December 31, 2015 and 2016, the Company had the following Series B-1 convertible preferred stock warrants issued and outstanding (in thousands, except share and per share data): Shares Fair Value Warrant Class 2015 2016 2015 2016 Issuance Date Price per Share Expiration Date Series B-1 25,568 25,568 $ 142 $ 303 June 2012 $ 5.8667 June 2022 Series B-1 167,428 167,428 $ 124 $ 263 July 2012 $ 5.8667 July 2019 Series B-1 145,801 145,801 $ 22 $ 46 August 2012 $ 5.8667 August 2019 Series B-1 10,517 10,517 $ 9 $ 19 November 2012 $ 5.8667 November 2022 Series B-1 156,851 156,851 $ 907 $ 929 February 2014 $ 0.1700 February 2021 Series B-1 173,862 173,862 $ 147 $ 315 September 2015 $ 5.8667 September 2025 Total 680,027 680,027 $ 1,351 $ 1,875 ​ ​ ​ ​ ​ ​ At December 31, 2017, the Company had the following common stock warrants issued and outstanding: Warrant Class Shares Issuance Date Price per Share Expiration Date Common stock warrant 165,925 July 2012 $ 5.8667 July 2019 Common stock warrant 61,502 August 2012 $ 5.8667 August 2019 Common stock warrant 156,851 February 2014 $ 0.1700 February 2021 Common stock warrant (1) 84,000 June 2017 $ 13.2000 June 2020 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, 2017
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, 2015 2016 2017 Fair value of common stock $0.85 $0.85-$3.06 $3.06-$19.56 Expected term (in years) 2-10 2-10 5-6 Risk-free interest rate 0.75%-2.10% 0.75%-1.77% 1.85%-2.29% Expected volatility 55% 55% 55% Expected dividend yield — — —
Schedule of Stock Option Activity	A summary of stock option activities under the 2005 Plan and 2017 Plan during the year ended December 31, 2017 is as follows: Number of Options Outstanding Weighted Average Exercise Price Outstanding at December 31, 2014 916,584 $ 0.89 Granted 112,068 $ 0.85 Exercised (45,199 ) $ 0.70 Canceled (45,203 ) $ 0.80 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 (74,990 ) $ 0.74 Canceled (22,499 ) $ 1.52 Outstanding at December 31, 2017 1,294,128 $ 1.79
Schedule of Stock Options Outstanding, Exercisable and Vested	Stock options outstanding, exercisable and vested were as follows: Outstanding at December 31, 2015 Weighted-average Remaining Contractual Life (years) Exercisable and Vested as of December 31, 2015 Weighted-average Remaining Contractual Life (years) Weighted-average Exercise Price 938,250 6.31 731,516 5.79 0.94 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 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 5.00 0.85
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, 2015 2016 2017 Costs $ 13 $ 11 $ 75 Sales and marketing 13 7 133 Research and development 32 18 69 General and administrative 79 47 351 Total $ 137 $ 83 $ 628

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments Under Non-cancelable Operating Lease	The following is a schedule of future minimum lease payments under the non-cancelable operating lease at December 31, 2017 (in thousands): 2018 $ 336 2019 346 2020 357 2021 305 Total $ 1,344

Organization and Description 37

Organization and Description of Business - Additional Information (Details)	Dec. 31, 2017Subsidiary
ShotSpotter (Pty) Ltd | South Africa
Business And Nature Of Operations [Line Items]
Number of subsidiary	1

Initial Public Offering - Addit

Initial Public Offering - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jun. 30, 2017	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 Sum39

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details)	1 Months Ended	12 Months Ended
	Dec. 31, 2016USD ($)shares	Dec. 31, 2017USD ($)CustomerSegmentBusinessshares	Dec. 31, 2016USD ($)Customershares	Dec. 31, 2015USD ($)	Jun. 12, 2017shares	Mar. 27, 2017shares	Dec. 31, 2009USD ($)
Accounting Policies [Line Items]
Number of authorized shares of common stock | shares	8,000,000	500,000,000	8,000,000
Reverse stock split, description		one-for-five and one-for-17 reverse stock splits
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%
Allowance for potential credit losses	$ 0	$ 0	$ 0
Impairment of long-lived assets held for use			0
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
Other comprehensive income (loss)				0
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.
Recognized revenue period		5 years
Deferred costs amortization period		5 years
ASC Topic 606
Accounting Policies [Line Items]
Recognized revenue period		3 years
Hurricane
Accounting Policies [Line Items]
Impairment of long-lived assets held for use		$ 800,000
Customer Concentration Risk | Revenues
Accounting Policies [Line Items]
Number of customers | Customer		1	2
Customer Concentration Risk | Accounts Receivable
Accounting Policies [Line Items]
Number of customers | Customer		3	3
Customer One | Customer Concentration Risk | Revenues
Accounting Policies [Line Items]
Concentration risk percentage		18.00%	12.00%
Customer One | Customer Concentration Risk | Accounts Receivable
Accounting Policies [Line Items]
Concentration risk percentage		18.00%	27.00%
Customer Two | Customer Concentration Risk | Revenues
Accounting Policies [Line Items]
Concentration risk percentage			12.00%
Customer Two | Customer Concentration Risk | Accounts Receivable
Accounting Policies [Line Items]
Concentration risk percentage		18.00%	16.00%
Customer Three | Customer Concentration Risk | Accounts Receivable
Accounting Policies [Line Items]
Concentration risk percentage		14.00%	11.00%
Sales and Marketing Expense
Accounting Policies [Line Items]
Advertising and promotion costs		$ 500,000	$ 500,000	300,000
General and Administrative Expense
Accounting Policies [Line Items]
Royalty expense		$ 60,000	$ 35,000	$ 35,000
Minimum
Accounting Policies [Line Items]
Subscription services initial contract period		1 year
Property and equipment estimated useful lives		3 years
Minimum | Leasehold Improvements
Accounting Policies [Line Items]
Lease term		5 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
Estimated useful life of intangible assets		3 years
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.

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jun. 30, 2017	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 (Details) - Fair Value Measurements Recurring - Level 3 - Convertible Preferred Stock Warrant Liability - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance, fair value	$ 1,875	$ 1,351	$ 1,204
Issuance of convertible preferred stock warrants	111		147
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)
Ending balance, fair value	$ 0	$ 1,875	$ 1,351

Intangible Assets, Net - Schedu

Intangible Assets, Net - Schedule of Intangible Assets Net (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Net	$ 95	$ 66
Patents
Finite Lived Intangible Assets [Line Items]
Gross	949	873
Accumulated Amortization	(854)	(807)
Net	$ 95	$ 66

Intangible Assets, Net - Additi

Intangible Assets, Net - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization expense	$ 47,000	$ 37,000	$ 86,000

Details of Certain Consolidat44

Details of Certain Consolidated Balance Sheet Accounts - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Prepaid Expense And Other Assets Current [Abstract]
Prepaid software and licenses	$ 407	$ 286
Prepaid insurance	211	25
Other prepaid expenses	137	171
Other	84	85
Total	$ 839	$ 567

Details of Certain Consolidat45

Details of Certain Consolidated Balance Sheet Accounts - Schedule of Property and Equipment, Net(Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 20,349	$ 16,774
Accumulated depreciation and amortization	(8,753)	(7,815)
Property and equipment, net	11,596	8,959
Deployed Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	17,091	13,240
Computer Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	1,123	912
Software
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	312	202
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	165	151
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	202	185
Construction in Progress
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 1,456	$ 2,084

Details of Certain Consolidat46

Details of Certain Consolidated Balance Sheet Accounts - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accrued Expenses And Other Current Liabilities [Abstract]
Payroll liabilities	$ 1,697	$ 1,146
Accrued employee paid time off	469	372
Accrued commissions	199	51
Accrued ESPP	115
Accrued interest		123
Royalties payable	125	225
Professional fees	328	76
Sales/ use tax payable	406	167
Other	476	199
Accrued expenses and other current liabilities	$ 3,815	$ 2,359

Impairment of Property and Eq47

Impairment of Property and Equipment - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Property Plant And Equipment [Line Items]
Impairment of property and equipment	$ 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, 2015USD ($)	Sep. 30, 2015USD ($)shares	Feb. 28, 2015USD ($)	Nov. 30, 2014USD ($)Installment	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	May 31, 2015USD ($)
Debt Instrument [Line Items]
Proceeds from lines of credit										$ 1,900,000
Unamortized debt issuance costs written-off									$ 321,000
Lines of credit, repaid in full										1,900,000
Notes payable									$ 12,000,000
Weighted average interest rate								11.54%	11.00%
Interest expense on debt								$ 1,100,000	$ 1,200,000
Amortization of debt issuance costs								132,000	131,000	88,000
Net proceeds from Initial public offering excluding underwriting discounts and commissions			$ 32,400,000					32,426,000
Series B-1 Convertible Preferred Stock
Debt Instrument [Line Items]
Number of shares called by warrant | shares					173,862
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
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
2014 Line of Credit
Debt Instrument [Line Items]
Line of credit, outstanding borrowed amount						$ 1,000,000					$ 900,000
Debt instrument interest rate						4.75%
Debt instrument basis spread						1.50%
Lines of credit, repaid in full					$ 1,900,000
2014 Line of Credit | Prime Rate
Debt Instrument [Line Items]
Debt instrument variable interest rate						3.25%
2015 Term Note | Other Expense, Net
Debt Instrument [Line Items]
Unamortized debt issuance costs written-off		$ 300,000
Loss consisting of prepayment fees and miscellaneous fees		$ 200,000
Notes Payable | 2014 Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity							$ 7,000,000
Notes Payable | 2014 Term Note
Debt Instrument [Line Items]
Maximum borrowing capacity							3,000,000
Line of credit, outstanding borrowed amount							3,000,000	0	0
Proceeds from lines of credit							$ 1,800,000
Debt instrument interest rate							5.75%
Debt instrument basis spread							2.50%
Debt instrument interest payment due end period							2015-10
Debt instrument number of periodic payment of principal and interest | Installment							24
Origination fees							$ 15,000
Facilities fees							70,000
Termination fees							$ 60,000
Interest expense recognized				$ 55,000
Unamortized debt issuance costs written-off				$ 77,000						$ 77,000
Notes Payable | 2014 Term Note | Prime Rate
Debt Instrument [Line Items]
Debt instrument variable interest rate							3.25%
Notes Payable | 2015 Term Note
Debt Instrument [Line Items]
Debt instrument number of periodic payment of principal and interest | Installment	36
Notes payable								$ 0	$ 11,700,000
Debt instrument maturity date	Oct. 31, 2020
Notes Payable | 2015 Term Note | Minimum
Debt Instrument [Line Items]
Debt instrument variable rate	11.00%
Notes Payable | 2015 Term Note | Three -Month LIBOR | Maximum
Debt Instrument [Line Items]
Debt instrument basis spread	7.50%
Notes Payable | 2015 Term Note | Three -Month LIBOR | Minimum
Debt Instrument [Line Items]
Debt instrument basis spread	2.50%

Financial Arrangements - Schedu

Financial Arrangements - Schedule of Notes Payable (Details) $ in Thousands	Dec. 31, 2016USD ($)
Debt Disclosure [Abstract]
Notes payable	$ 12,000
Unamortized debt issuance costs	(321)
Current maturities of term note	(667)
Total notes payable, net of current maturities	$ 11,012

Related Party Transactions - Ad

Related Party Transactions - Additional Informtion (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transactions [Abstract]
Revenue recognized from reseller	$ 700,000	$ 200,000	$ 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, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic	$ (10,125)	$ (6,744)	$ (6,191)
Foreign	305	(116)
Net Loss	$ (9,820)	$ (6,860)	$ (6,191)

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, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income tax at statutory rate	$ (3,339)	$ (2,331)	$ (2,104)
Change in valuation allowance	(8,354)	2,146	3,137
Change in tax rate	9,788
Change in deferreds	(39)		(852)
State tax	536	9	(184)
Mark-to-market on warrants	1,267	178
Other	301	$ (2)	$ 3
Total	$ 160

Income Taxes - Schedule of Comp

Income Taxes - Schedule of Company's Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Net operating losses	$ 20,139	$ 28,677
Credits	1,654	1,414
Accruals and reserves	643	519
Deferred revenue and contract costs	464	871
Gross deferred tax assets	22,900	31,481
Valuation allowance	(22,789)	(31,143)
Net deferred tax assets	111	338
Deferred tax liabilities:
Fixed assets and intangibles	$ (111)	$ (338)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Decrease in valuation allowance		$ (8,400,000)
Unrecognized tax benefits		620,000	$ 574,000	$ 813,000
Interest or penalties accrued		0
Provisional income tax expense (benefit)		9,800,000
Scenario Plan
Income Taxes [Line Items]
Corporate income tax rate	21.00%
California
Income Taxes [Line Items]
Research and experimental credits carryforwards		$ 1,300,000
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		$ 80,200,000
Net operating loss carryforwards, expiration		2018 through 2036
Research and experimental credits carryforwards		$ 1,200,000
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		$ 50,800,000
Net operating loss carryforwards, expiration		2018 through 2036

Income Taxes - Schedule of Unre

Income Taxes - Schedule of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ 574	$ 813
Increases for current year tax positions	46	63
Increases for prior year tax positions		(302)
Balance at end of year	$ 620	$ 574

Capital Stock - Summary of Outs

Capital Stock - Summary of Outstanding Convertible Preferred Stock (Details) - USD ($) $ in Thousands	Dec. 31, 2017	May 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
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	4,773,000	4,773,000
Temporary equity, shares issued	0	3,848,023	3,848,023
Temporary equity, shares outstanding	0	3,848,023	3,848,023	3,848,023	3,507,117
Temporary equity, aggregate liquidation preference		$ 22,575	$ 22,575
Series A-2 Convertible Preferred Stock
Class Of Stock [Line Items]
Temporary equity, shares authorized	1,177,000	1,177,000	1,177,000
Temporary equity, shares issued	0	1,176,423	1,176,423
Temporary equity, shares outstanding	0	1,176,423	1,176,423	1,176,423	1,176,423
Temporary equity, aggregate liquidation preference		$ 20,000	$ 20,000

Capital Stock - Additional Info

Capital Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Class Of Stock [Line Items]
Conversion of preferred stock into common stock, value		$ 42,075
Reclassification of convertible preferred stock warrant liability into additional paid-in capital	$ 5,700	$ 5,711
Preferred stock, shares outstanding		0	0
Common stock, shares authorized		500,000,000	8,000,000
Common stock, par value		$ 0.005	$ 0.005
Common stock, shares issued		9,827,129	1,616,996
Common stock, shares outstanding		9,827,129	1,616,996
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
Additional Paid-in Capital
Class Of Stock [Line Items]
Conversion of preferred stock into common stock, value		42,052
Reclassification of convertible preferred stock warrant liability into additional paid-in capital	$ 42,100	$ 42,100

Capital Stock - Schedule of Com

Capital Stock - Schedule of Common Stock Reserved for Future Issuance (Details) - shares		Dec. 31, 2017	Dec. 31, 2016
Class Of Stock [Line Items]
Common stock reserved for future issuance		2,813,593	6,890,085
Warrants to Purchase Common Stock
Class Of Stock [Line Items]
Common stock reserved for future issuance		468,278
Options Outstanding
Class Of Stock [Line Items]
Common stock reserved for future issuance		1,294,128	1,130,141
Shares Available for Future Grant
Class Of Stock [Line Items]
Common stock reserved for future issuance		1,003,875	390,164
Unvested Restricted Stock Units
Class Of Stock [Line Items]
Common stock reserved for future issuance		47,312
Series B-1 Convertible Preferred Stock Warrants
Class Of Stock [Line Items]
Common stock reserved for future issuance			680,027
Series B-1 Convertible Preferred Stock
Class Of Stock [Line Items]
Common stock reserved for future issuance			3,848,023
Series A-2 Convertible Preferred Stock
Class Of Stock [Line Items]
Common stock reserved for future issuance	[1]		841,730
Convertible Preferred Stock and Warrants
Class Of Stock [Line Items]
Common stock reserved for future issuance			5,369,780
[1]	Reflects the effect of an amendment and restatement of the Company’s amended and restated certificate of incorporation in March 2017 to implement a conversion feature for the Series A-2 convertible preferred stock.

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, 2017	Dec. 31, 2016	Dec. 31, 2015
Numerator:
Net loss	$ (9,980)	$ (6,860)	$ (6,191)
Denominator:
Weighted-average shares outstanding, basic and diluted	6,197,775	1,602,402	1,552,780
Net loss per share	$ (1.61)	$ (4.28)	$ (3.99)

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, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	1,809,718	6,499,921	6,308,030
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	1,294,128	1,130,141	938,250
Unvested Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	47,312
The March 2017 Preferred stock warrant or common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	468,278	680,027	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	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	841,730

Convertible Preferred Stock W61

Convertible Preferred Stock Warrants and Common Stock Warrants - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Mar. 28, 2017	Dec. 31, 2015	Sep. 30, 2015
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
Fair value of warrants	300,000		$ 1,875,000		$ 1,351,000
Net proceeds from Initial public offering excluding underwriting discounts and commissions	$ 32,400,000	$ 32,426,000
Series B-1 Convertible Preferred Stock
Class Of Warrant Or Right [Line Items]
Number of shares called by warrant						173,862
Fair value of warrants						$ 147,000
Series B-1 Convertible Preferred Stock | The March 28, 2017 Preferred stock warrant
Class Of Warrant Or Right [Line Items]
Number of shares called by warrant	61,363			76,704
Fair value of warrants				$ 111,000
Class of warrant, exercise price				$ 5.8667
Warrants Not Settleable in Cash
Class Of Warrant Or Right [Line Items]
Conversion of preferred stock into common stock, shares		191,263
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 W62

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, 2017	Jun. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Class Of Warrant Or Right [Line Items]
Shares of warrants issued and outstanding		468,278		680,027	680,027
Fair value of warrants issued and outstanding			$ 300	$ 1,875	$ 1,351
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	25,568
Fair value of warrants issued and outstanding				$ 303	$ 142
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	167,428
Fair value of warrants issued and outstanding				$ 263	$ 124
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	145,801
Fair value of warrants issued and outstanding				$ 46	$ 22
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	10,517
Fair value of warrants issued and outstanding				$ 19	$ 9
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	156,851
Fair value of warrants issued and outstanding				$ 929	$ 907
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	173,862
Fair value of warrants issued and outstanding				$ 315	$ 147
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		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		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		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
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)	1 Months Ended	12 Months Ended
	May 31, 2017shares	Dec. 31, 2017USD ($)Participant$ / sharesshares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)shares	Jun. 30, 2017shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance		2,813,593	6,890,085
Unvested options resulting from early exercises		0	0	0
Aggregate intrinsic value of options exercised | $		$ 800,000	$ 23,000,000	$ 7,000,000
Total intrinsic value of all outstanding options | $		15,900,000	2,500,000	100,000
Total unrecognized stock-based compensation cost related to unvested stock options | $		$ 800,000	$ 200,000
Total unrecognized stock-based compensation cost related to unvested stock options, recognized ratably over a weighted-average period		3 years 2 months 12 days	3 years 2 months 12 days
Cash received from exercise of stock options | $		$ 55,000	$ 25,000	$ 31,000
Income tax benefits from stock-based compensation | $		$ 0
Percentage of forfeiture rate		0.00%	0.00%	0.00%
Restricted Stock Unit
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Units, Granted		47,312
Minimum | Restricted Stock Unit
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period		7 months
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
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	1,003,875
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%
Number of shares authorized for issuance					900,000
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
ISO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Ownership percentage, minimum		10.00%
ISO | 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		150,000
Percentage of number of shares of common stock outstanding			2.00%
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
Shares issued under ESPP		34,133
Shares outstanding under ESPP		34,133

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, 2017	Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of common stock			$ 0.85
Expected volatility	55.00%	55.00%	55.00%
Risk-free interest rate, minimum	1.85%	0.75%	0.75%
Risk-free interest rate, maximum	2.29%	1.77%	2.10%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of common stock	$ 3.06	$ 0.85
Expected term (in years)	5 years	2 years	2 years
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of common stock	$ 19.56	$ 3.06
Expected term (in years)	6 years	10 years	10 years

Equity Incentive Plans - Sche65

Equity Incentive Plans - Schedule of Stock Option Activity (Details) - 2005 Plan and 2017 Plan - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of Options Outstanding, Beginning Balance	1,130,141	938,250	916,584
Number of Options Outstanding, Granted	261,476	272,769	112,068
Number of Options Outstanding, Exercised	(74,990)	(33,395)	(45,199)
Number of Options Outstanding, Canceled	(22,499)	(47,483)	(45,203)
Number of Options Outstanding, Ending Balance	1,294,128	1,130,141	938,250
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Price, Beginning Balance	$ 0.86	$ 0.90	$ 0.89
Weighted Average Exercise Price, Granted	5.52	1.27	0.85
Weighted Average Exercise Price, Exercised	0.74	0.75	0.70
Weighted Average Exercise Price, Canceled	1.52	4.14	0.80
Weighted Average Exercise Price, Ending Balance	$ 1.79	$ 0.86	$ 0.90

Equity Incentive Plans - Sche66

Equity Incentive Plans - Schedule of Stock Options Outstanding, Exercisable and Vested (Details) - 2005 Plan and 2017 Plan - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding balance	1,294,128	1,130,141	938,250	916,584
Weighted-average Remaining Contractual Life (years)	6 years 2 months 19 days	6 years 3 months 14 days	6 years 3 months 21 days
Exercisable and Vested balance	883,959	842,261	731,516
Weighted-average Remaining Contractual Life (years)	5 years	5 years 3 months 25 days	5 years 9 months 14 days
Weighted-average Exercise Price	$ 0.85	$ 0.74	$ 0.94

Equity Incentive Plans - Sche67

Equity Incentive Plans - Schedule of Stock-Based Compensation Expense Recorded in Consolidated Statements of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 628	$ 83	$ 137
Costs
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	75	11	13
Sale and Marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	133	7	13
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	69	18	32
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 351	$ 47	$ 79

Benefit Plan - Additional Infor

Benefit Plan - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
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) $ in Millions	1 Months Ended	12 Months Ended
	Jul. 31, 2007shares	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Commitments And Contingencies Disclosure [Line Items]
Non-cancelable operating lease expiration period		2,021
Rent expense | $		$ 0.3	$ 0.3	$ 0.3
Lawsuit filing date		November 6, 2017
Number of options granted | shares	350,000
Claims description		The Contractors claim that our subsequent one-for-five and one-for-17 reverse stock splits should not apply to their option awards.
Reverse stock split, description		one-for-five and one-for-17 reverse stock splits
Option One
Commitments And Contingencies Disclosure [Line Items]
Reverse stock split, conversion ratio		0.2
Option Two
Commitments And Contingencies Disclosure [Line Items]
Reverse stock split, conversion ratio		0.0588

Commitments and Contingencies70

Commitments and Contingencies - Schedule of Future Minimum Lease Payments Under Non-cancelable Operating Lease (Details) $ in Thousands	Dec. 31, 2017USD ($)
Operating Leases Future Minimum Payments Due [Abstract]
2,018	$ 336
2,019	346
2,020	357
2,021	305
Total	$ 1,344