Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2021	Aug. 06, 2021
Document and Entity Information [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Jun. 30, 2021
Entity File Number	001-39412
Entity Registrant Name	FATHOM HOLDINGS INC.
Entity Incorporation, State or Country Code	NC
Entity Tax Identification Number	82-1518164
Entity Address, Address Line One	2000 Regency Parkway Drive
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	Cary
Entity Address State Or Province	NC
Entity Address, Postal Zip Code	27518
City Area Code	888
Local Phone Number	455-6040
Title of 12(b) Security	Common Stock, No Par Value
Trading Symbol	FTHM
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		14,796,102
Entity Central Index Key	0001753162
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Amendment Flag	false