CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net loss	$ (20,963)	$ (12,528)	$ (29,853)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	3,112	6,023	5,150
Stock-based compensation expense	2,839	846	1,081
Change in fair value of deferred acquisition consideration	427	134	0
Provision for transaction losses and eCommerce returns	428	630	1,047
Amortization of costs to obtain revenue contracts	447	487	494
Amortization of debt issuance costs	0	0	334
Deferred rent	(194)	(2,837)	(2,006)
Deferred income taxes	0	0	(424)
Other, net	21	(11)	(149)
Changes in operating assets and liabilities:
Accounts receivable	52	(652)	(123)
Prepaid and other current assets	(1,145)	359	(2,993)
Receivables from payment processors	910	553	(1,883)
Other assets	(145)	(163)	499
Accounts payable and accrued expenses	5,055	2,219	2,794
Payables due to sellers	5,732	1,592	804
Other current liabilities and other liabilities	(977)	(95)	6,759
Net cash used in operating activities	(4,401)	(3,443)	(18,469)
Cash flows from investing activities:
Development of internal-use software	(2,110)	(1,782)	(4,191)
Proceeds from repayment of notes receivable with related party	0	3,112	0
Purchases of property and equipment	(129)	(44)	(1,911)
Acquisition of Design Manager, net of cash acquired	0	0	(2,308)
Other, net	(30)	0	0
Net cash (used in) provided by investing activities	(2,269)	1,286	(8,410)
Cash flows from financing activities:
Proceeds from issuance of common stock in initial public offering, net of underwriting discounts and commissions	122,993	0	0
Proceeds from exercise of stock options	2,729	2,010	343
Proceeds from the issuance of Series D redeemable convertible preferred stock, net of issuance costs	0	0	75,863
Payment of deferred acquisition consideration	(640)	0	0
Repayment of long-term debt	0	0	(15,000)
Payment of deferred offering costs	(5,032)	(448)	0
Debt refinancing costs	0	0	(250)
Net cash provided by financing activities	120,050	1,562	60,956
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	(16)	(14)	117
Net increase (decrease) in cash, cash equivalents, and restricted cash	113,364	(609)	34,194
Cash, cash equivalents, and restricted cash at beginning of the period	58,195	58,804	24,610
Cash, cash equivalents, and restricted cash at end of the period	171,559	58,195	58,804
Supplemental disclosure of cash flow information:
Cash paid for income taxes	69	11	2
Cash paid for interest	16	14	456
Supplemental disclosure of non-cash activities:
Accretion of redeemable convertible preferred stock to redemption value	7,061	15,095	13,744
Conversion of redeemable convertible preferred stock in connection with initial public offering	305,586	872	0
Change in deferred offering costs included in accounts payable and accrued expenses	(872)	0	0
Issuance of common stock as acquisition consideration	767	0	791
Deferred acquisition consideration	0	0	846
Impact of adoption of ASC 606	$ 0	$ 0	$ (882)