Cover	May 13, 2025
Cover [Abstract]
Document Type	8-K
Amendment Flag	false
Document Period End Date	May 13, 2025
Entity File Number	001-42143
Entity Registrant Name	Alumis Inc.
Entity Central Index Key	0001847367
Entity Tax Identification Number	86-1771129
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	280 East Grand Avenue
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	650
Local Phone Number	231-6625
Written Communications	false
Soliciting Material	false
Pre-commencement Tender Offer	false
Pre-commencement Issuer Tender Offer	false
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Trading Symbol	ALMS
Security Exchange Name	NASDAQ
Entity Emerging Growth Company	true
Elected Not To Use the Extended Transition Period	false