v3.26.1
Cover - shares
 3 Months Ended
Mar. 31, 2026
May 04, 2026
Entity Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 31, 2026  
Document Transition Report false  
Entity File Number 001-40246  
Entity Registrant Name Nextdoor Holdings, Inc  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 86-1776836  
Entity Address, Address Line One 420 Taylor Street  
Entity Address, City or Town San Francisco  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 94102  
City Area Code 415  
Local Phone Number 344-0333  
Title of 12(b) Security Class A common stock, par value $0.0001 per share  
Trading Symbol NXDR  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Amendment Flag false  
Entity Central Index Key 0001846069  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q1  
Current Fiscal Year End Date --12-31  
Class A Common Stock    
Entity Information [Line Items]    
Entity Common Stock, Shares Outstanding   253,892,530
Class B Common Stock    
Entity Information [Line Items]    
Entity Common Stock, Shares Outstanding   127,495,195