Proton Authenticator

Proton Authenticator is a free app for generating time-based one-time codes on phones and computers. It suits people who want offline access and optional encrypted syncing without paying; the trade-off is that sync requires signing in to a Proton Account.

Overview

The app generates TOTP codes on your device, so you can retrieve them without an internet connection. A Proton Account is not required for using the app on one device, but you must sign in to sync codes across devices. That makes it a practical standalone choice, with an account step for anyone who wants shared access.

Proton Authenticator is open source, and its vault can be unlocked with face or fingerprint recognition. Those features offer code visibility and a biometric gate to the vault, while the core job remains focused on generating login codes.

Key features

Moving and backing up codes

You can import codes from Google Authenticator, 2FAS, Aegis Authenticator, Bitwarden Authenticator, Ente Auth, and LastPass Authenticator, then export codes from Proton Authenticator if you later move elsewhere. The broad import support makes switching more feasible than starting a code collection from scratch.

Codes can be backed up locally or in the cloud. Sync uses end-to-end encryption, and Proton says its servers cannot access the unencrypted data; synced entries use 256-bit AES-GCM. This offers cross-device convenience without making the codes readable to the service, though sync still depends on signing in.

Pricing

Proton Authenticator is free across all platforms, with no ads or tracking. There is no paid tier to unlock or trial to manage, making it suitable for anyone who needs a TOTP app without an ongoing subscription. The meaningful choice is whether to use it without an account or sign in for sync.

Platforms

Apps are available for Android, iOS, Linux, macOS, and Windows. The Android app is also available on F-Droid. This breadth suits people who want the same authenticator option across mobile and desktop; offline code display also means an internet connection is not needed simply to retrieve a code.

Who it's for

Choose Proton Authenticator if you want a free, open-source TOTP app with offline code access, migration support from several established authenticators, and optional encrypted sync. It is less suitable if you do not want to sign in but need codes synchronized across devices, or if your preferred approach depends on a hardware key.

Pros and cons

Pros

• Offline TOTP codes let you retrieve login codes without a network connection.
• Imports from six named authenticator apps and export support make it easier to switch in either direction.
• Optional sync and local or cloud backups provide more than one way to keep codes backed up.
• It is open source, free on all supported platforms, and has no ads or tracking.

Cons

• Sync requires signing in to a Proton Account, so it is not account-free across multiple devices.
• Users seeking a hardware-key-based authenticator should choose another option.

Alternatives

Authenticator apps is a broader place to compare options. Consider Yubico Authenticator if you specifically want credentials stored and generated with a YubiKey; that requirement is its main trade-off against a software-only choice. Ente Auth is another free, open-source option with data import and export support.

Bitwarden is worth considering if you want an authenticator alongside password management, including unlimited devices and passwords on its free plan. Zoho OneAuth fits users looking for free OTP authentication with backup and recovery for work or personal accounts.

Duo Mobile is an alternative for readers who want a free plan capped at 10 users, with a paid Essentials tier at $3 a month. SAASPASS Authenticator offers personal use through its mobile app on a free plan. Authy is a free mobile option with encrypted cloud backup and multi-device support, while Salesforce Authenticator combines mobile MFA verification, push notifications, and TOTP codes.

Verdict

Proton Authenticator is a strong fit for anyone who wants a no-cost TOTP app across mobile and desktop, especially if offline access, open-source code, and flexible imports matter. Its encrypted sync is useful but requires a Proton Account; look elsewhere if you need synchronized codes without signing in or want an authenticator built around a hardware key.