Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Convertible Debt	Common Stock	Common Stock Convertible Debt	Additional Paid-In Capital	Additional Paid-In Capital Convertible Debt	Accumulated Other Comprehensive Income	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2017	12,641,035
Beginning balance at Dec. 31, 2017	$ 140,452
Convertible Preferred Stock
Issuance of convertible preferred stock (in shares)	7,884
Issuance of convertible preferred stock	$ 83
Ending balance (in shares) at Dec. 31, 2018	12,648,919
Ending balance at Dec. 31, 2018	$ 140,535
Beginning balance (in shares) at Dec. 31, 2017			1,701,293
Beginning balance at Dec. 31, 2017	$ (149,394)		$ 2		$ 20,718		$ 1,207	$ (171,321)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	18,153		18,153
Issuance of common stock upon exercise of stock options	$ 31				31
Change in shares subject to repurchase	24				24
Stock-based compensation expense	366				366
Currency translation adjustment	126						126
Change in unrealized (losses) gains on marketable securities	0
Net loss	(18,479)							(18,479)
Ending balance (in shares) at Dec. 31, 2018			1,719,446
Ending balance at Dec. 31, 2018	$ (167,326)		$ 2		21,139		1,333	(189,800)
Convertible Preferred Stock
Issuance of convertible preferred stock (in shares)	4,934,231
Issuance of convertible preferred stock	$ 64,804
Ending balance (in shares) at Dec. 31, 2019	17,583,150
Ending balance at Dec. 31, 2019	$ 205,339
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	390,318		390,318
Issuance of common stock upon exercise of stock options	$ 528				528
Change in shares subject to repurchase	$ (281)				(281)
Repurchase of early exercised common stock options (in shares)			(9,147)
Common stock retired during the year and repurchase of early exercised common stock options (in shares)	(414)		(414)
Stock-based compensation expense	$ 364				364
Currency translation adjustment	34						34
Change in unrealized (losses) gains on marketable securities	6						6
Net loss	$ (20,703)							(20,703)
Ending balance (in shares) at Dec. 31, 2019	2,100,203		2,100,203
Ending balance at Dec. 31, 2019	$ (187,378)		$ 2		21,750		1,373	(210,503)
Convertible Preferred Stock
Issuance of convertible preferred stock (in shares)	213,876
Issuance of convertible preferred stock	$ 2,260
Conversion of convertible preferred stock into common stock (in shares)	(17,797,026)
Conversion of convertible preferred stock into common stock	$ (207,599)
Ending balance (in shares) at Dec. 31, 2020	0
Ending balance at Dec. 31, 2020	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	1,745,040		1,745,040
Issuance of common stock upon exercise of stock options	$ 2,705		$ 2		2,703
Conversion of securities into common stock (in shares)			17,797,026	2,561,484
Conversion of securities into common stock	207,599	$ 30,592	$ 18	$ 3	207,581	$ 30,589
Issuance of common stock upon initial public offering, net of issuance cost of $17,120 (in shares)			11,500,000
Issuance of common stock upon initial public offering, net of issuance costs and underwriting discount of $17,108	201,392		$ 11		201,381
Change in shares subject to repurchase	(346)				(346)
Repurchase of early exercised common stock options (in shares)			(10,000)
Stock-based compensation expense	3,489				3,489
Currency translation adjustment	318						318
Change in unrealized (losses) gains on marketable securities	(6)						(6)
Net loss	$ (32,231)							(32,231)
Ending balance (in shares) at Dec. 31, 2020	35,693,753		35,693,753
Ending balance at Dec. 31, 2020	$ 226,134		$ 36		$ 467,147		$ 1,685	$ (242,734)