Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Mar. 25, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	000-52776
Entity Registrant Name	Appgate, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-3547231
Entity Address, Address Line One	2 Alhambra Plaza
Entity Address, Address Line Two	Suite PH-1-B
Entity Address, City or Town	Coral Gables
Entity Address, State or Province	FL
Entity Address, Postal Zip Code	33134
City Area Code	866
Local Phone Number	524-4782
Title of 12(g) Security	Common Stock, $0.001 par value
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 45.1
Entity Common Stock, Shares Outstanding		131,793,660
Documents Incorporated by Reference	None.
Entity Central Index Key	0001353538
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Amendment Flag	false