XML 11 R1.htm IDEA: XBRL DOCUMENT v3.23.3
Cover - shares
 9 Months Ended
Sep. 30, 2023
Oct. 31, 2023
Document Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Sep. 30, 2023  
Document Transition Report false  
Entity File Number 001-41806  
Entity Registrant Name KLAVIYO, INC.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 46-0989964  
Entity Address, Address Line One 125 Summer Street  
Entity Address, Address Line Two 6th Floor  
Entity Address, City or Town Boston  
Entity Address, State or Province MA  
Entity Address, Postal Zip Code 02110  
City Area Code 617  
Local Phone Number 213-1788  
Title of 12(b) Security Series A common stock, par value $0.001 per share  
Trading Symbol KVYO  
Security Exchange Name NYSE  
Entity Current Reporting Status No  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Shell Company false  
Amendment Flag false  
Entity Central Index Key 0001835830  
Document Fiscal Period Focus Q3  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2023  
Series A Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   37,151,631
Series B Common Stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   221,539,416