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Proton AuthenticatorZero-TOTP
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.

Windows, Linux, Android, iOS Web, Self-hosted
  • End-to-end encrypted sync between devices, which most free authenticators lack
  • Apps for Android, iOS, Windows, Linux and macOS
  • Zero-knowledge encryption of stored TOTP secrets
  • Use the hosted service or self-host it
  • Sync requires a Proton account
  • Keeping codes on the same desktop you log in from weakens second-factor separation
  • iOS app still in development and CLI only planned
  • Small project with a limited contributor base
Downloadable app Web application, Self-hosted
Open source Open source
License: GPL-3.0 License: GPL-3.0
No account needed Account needed
Works offline Not stated if it works offline

Checked September 21, 2026

Checked October 2, 2026

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