Summary of significant accounting policies - Potentially dilutive securities (Details) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Potentially dilutive securities
Total shares of common stock equivalents	549,235	249,293	188,552
Convertible preferred stock
Potentially dilutive securities
Total shares of common stock equivalents	56,227
Options to purchase common stock
Potentially dilutive securities
Total shares of common stock equivalents	480,274	229,308	188,552
Restricted stock units
Potentially dilutive securities
Total shares of common stock equivalents	12,734	19,985