Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2024	Nov. 04, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Trading Symbol	JANX
Security12b Title	Common Stock, $0.001 par value per share
Security Exchange Name	NASDAQ
Entity Registrant Name	Janux Therapeutics, Inc.
Entity Central Index Key	0001817713
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		52,482,020
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-40475
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-2289112
Entity Address, Address Line One	10955 Vista Sorrento Parkway, Suite 200
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92130
City Area Code	858
Local Phone Number	751-4493