Net loss per share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net loss	$ (75,665)	$ (44,082)	$ (43,037)
Denominator:
Weighted-average common shares outstanding, basic and diluted	29,945,954	25,876,376	17,859,935
Weighted-average Series A convertible preferred shares outstanding, basic and diluted, presented as if converted into common stock	2,887,636	162,732
Total number of shares used to calculate net loss per share, basic	32,833,590	26,039,108	17,859,935
Total number of shares used to calculate net loss per share, diluted	32,833,590	26,039,108	17,859,935
Net loss per share - basic	$ (2.30)	$ (1.69)	$ (2.41)
Net loss per share - diluted	$ (2.30)	$ (1.69)	$ (2.41)
Number of common stock issued upon conversion of each share of Preferred Stock	1,000
Number of common stock issuable upon conversion of Series A convertible preferred stock	1,697,000