Stock-based compensation - Stock Option Rollforward (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2022	Dec. 31, 2021
Number of Options
Beginning balance, shares	7,757,401
Granted, shares	3,396,093
Exercised, shares	(187,151)
Canceled/Forfeited, shares	(280,046)
Expired, shares	(9,005)
Ending balance, shares	10,677,292	7,757,401
Exercisable, shares	1,889,711
Vested and expected to vest, shares	10,677,292
Weighted Average Exercise Price per Share
Beginning balance, usd per share	$ 3.72
Granted, usd per share	7.74
Exercised, usd per share	1.14
Canceled/Forfeited, usd per share	6.78
Expired, usd per share	1.12
Ending balance, usd per share	4.97	$ 3.72
Exercisable, weighted average price, usd per share	$ 1.16
Weighted Average Remaining Contractual Term (in years)	9 years 1 month 6 days	9 years 2 months 12 days
Exercisable, weighted average remaining contractual term (in years)	8 years 6 months
Vested and expected to vest, contractual term (in years)	9 years 1 month 6 days
Intrinsic value, shares outstanding	$ 42,496	$ 40,939
Exercisable, aggregate intrinsic value	13,746
Vested and expected to vest, aggregate intrinsic value	$ 42,496

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.