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Proton Authenticator vs Microsoft Authenticator: catalog facts
Proton Authenticator	Microsoft Authenticator
Free Free and open source under the GPL, with no advertising. A Proton account is used for…	Free Free app from Microsoft for Android and iOS.
Windows, Linux, Android, iOS	Android, iOS
End-to-end encrypted sync between devices, which most free authenticators lack Apps for Android, iOS, Windows, Linux and macOS	Passwordless sign-in for Microsoft and work accounts Commonly required by employers using Microsoft sign-in
Sync requires a Proton account Keeping codes on the same desktop you log in from weakens second-factor separation	Mobile only, with no desktop app Most useful inside the Microsoft account ecosystem
Downloadable app	Downloadable app
Open source	Closed 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 23, 2026

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