Stockholders' Deficit - Schedule of Shares Reserved for Future Issuance (Details) - shares	Sep. 30, 2021	Dec. 31, 2020
Class Of Stock [Line Items]
Warrants to purchase redeemable convertible preferred stock	77,842	77,842
Common stock options issued and outstanding	2,170,894	2,466,594
Common stock available for future grants	59,187	67,010
Series A Redeemable Convertible Preferred Stock Outstanding
Class Of Stock [Line Items]
Convertible preferred stock reserved for future issuance	450,692	450,692
Series B Redeemable Convertible Preferred Stock Outstanding
Class Of Stock [Line Items]
Convertible preferred stock reserved for future issuance	675,397	675,397
Series C Redeemable Convertible Preferred Stock Outstanding
Class Of Stock [Line Items]
Convertible preferred stock reserved for future issuance	2,223,888	2,223,888
Series D Redeemable Convertible Preferred Stock Outstanding
Class Of Stock [Line Items]
Convertible preferred stock reserved for future issuance	9,047,861	9,047,861