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

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