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Proton Authenticator vs Aegis Authenticator: catalog facts
Proton Authenticator	Aegis Authenticator
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, with no accounts and no paid tier.
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	The vault is encrypted with AES-256-GCM, unlocked by password with scrypt or by biometrics Automatic backups of the vault to a location you choose, plain or encrypted
Sync requires a Proton account Keeping codes on the same desktop you log in from weakens second-factor separation	Android only No cloud sync; you own the backup process
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 21, 2026

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