CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Statement [Abstract]
Revenue	$ 443,644	$ 376,815	$ 307,675
Cost of revenue	86,308	65,477	52,327
Gross profit	357,336	311,338	255,348
Operating expenses
Sales and marketing	176,593	144,340	126,871
Research and development	97,170	80,080	57,442
General and administrative	106,385	78,610	77,410
Exit Costs	0	0	1,292
Total operating expenses	380,148	303,030	263,015
(Loss) income from operations	(22,812)	8,308	(7,667)
Other income, net	12,710	12,094	12,313
(Loss) income before income taxes	(10,102)	20,402	4,646
Provision for income taxes	9,395	13,027	3,696
Net (loss) income	(19,497)	7,375	950
Net loss attributable to noncontrolling interest in consolidated subsidiaries	(540)	(861)	0
Net (loss) income attributable to Semrush Holdings, Inc.	$ (18,957)	$ 8,236	$ 950
Net (loss) income attributable to Semrush Holdings, Inc. per share attributable to common stockholders—basic (in dollars per share)	$ (0.13)	$ 0.06	$ 0.01
Net (loss) income attributable to Semrush Holdings, Inc. per share attributable to common stockholders—diluted (in dollars per share)	$ (0.13)	$ 0.06	$ 0.01
Weighted-average number of shares of common stock used in computing net (loss) income per share attributable to common stockholders—basic (in shares)	148,539,990	145,864,755	142,593,000
Weighted-average number of shares of common stock used in computing net (loss) income per share attributable to common stockholders—diluted (in shares)	148,539,990	148,861,846	146,065,333
Comprehensive (loss) income
Net (loss) income	$ (19,497)	$ 7,375	$ 950
Other comprehensive income (loss):
Foreign currency translation adjustments	4,690	(1,585)	451
Unrealized gain on investments	18	116	3
Comprehensive (loss) income	(14,789)	5,906	1,404
Comprehensive loss attributable to noncontrolling interest in consolidated subsidiaries	(540)	(861)	0
Comprehensive (loss) income attributable to Semrush Holdings, Inc.	$ (14,249)	$ 6,767	$ 1,404