v3.25.1
Cover - shares
 3 Months Ended
Mar. 31, 2025
May 01, 2025
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 31, 2025  
Document Transition Report false  
Entity File Number 001-39965  
Entity Registrant Name ON24, INC.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 94-3292599  
Entity Address, Address Line One 50 Beale Street, 8th Floor  
Entity Address, City or Town San Francisco  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 94105  
City Area Code 415  
Local Phone Number 369-8000  
Title of 12(b) Security Common Stock, par value $0.0001 per share  
Trading Symbol ONTF  
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 true  
Entity Ex Transition Period false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   42,475,166
Amendment Flag false  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q1  
Entity Central Index Key 0001110611  
Current Fiscal Year End Date --12-31