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2FAS vs Proton Authenticator: catalog facts
2FAS	Proton Authenticator
Free Free and open source. Some components are source-available.	Free Free and open source under the GPL, with no advertising. A Proton account is used for…
Android, iOS, Browser extension	Windows, Linux, Android, iOS
Browser extension approves codes on the phone instead of typing them Encrypted backups to your own iCloud or Google Drive account	End-to-end encrypted sync between devices, which most free authenticators lack Apps for Android, iOS, Windows, Linux and macOS
Mobile-first; there is no standalone desktop app Push approval needs the browser extension installed on each machine	Sync requires a Proton account Keeping codes on the same desktop you log in from weakens second-factor separation
Downloadable app, Browser extension	Downloadable app
Open source	Open source
License not stated	License: GPL-3.0
Not stated if an account is needed	No account needed
Not stated if it works offline	Works offline
Official website Full listing and sources Checked September 22, 2026	Official website Full listing and sources Checked September 21, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.