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Proton Authenticator vs Stratum: catalog facts
Proton Authenticator	Stratum
Free Free and open source under the GPL, with no advertising. A Proton account is used for…	Free Free and open source under the GPL 3.0 license.
Windows, Linux, Android, iOS	Android
End-to-end encrypted sync between devices, which most free authenticators lack Apps for Android, iOS, Windows, Linux and macOS	Encrypted backups with import from other apps and export at any time Supports TOTP, HOTP and mOTP
Sync requires a Proton account Keeping codes on the same desktop you log in from weakens second-factor separation	Android only, with no iOS or desktop version Only handles one-time codes, not passwords
Downloadable app	Downloadable app
Open source	Open source
License: GPL-3.0	License: GPL-3.0
No account needed	No account needed
Works offline	Works offline
Official website Full listing and sources Checked September 21, 2026	Official website Full listing and sources Checked September 24, 2026

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