Proton Authenticator APK 1.3.9 for Android: Direct F-Droid Download

Proton Authenticator APK 1.3.9 is a current open-source two-factor authentication app available from F-Droid. F-Droid lists version 1.3.9 with version code 10309000, added on July 15, 2026.

The app can generate TOTP codes offline and optionally synchronize authenticator data across devices using Proton’s encrypted account infrastructure.

Direct Proton Authenticator APK download

Download Proton Authenticator 1.3.9 APK

App details

• Package: proton.android.authenticator.fdroid
• Version: 1.3.9
• Version code: 10309000
• Minimum Android: Android 8.1+
• Architectures: arm64-v8a, armeabi-v7a, x86_64
• Approximate APK size: 89 MiB
• License: GPL-3.0-or-later
• Rights status: Open-source / F-Droid direct distribution

What Proton Authenticator does

Proton Authenticator generates time-based one-time passwords for two-factor authentication. It works offline for code generation and does not require a Proton account for basic local use.

Optional account features can synchronize 2FA entries across supported devices using end-to-end encryption. The app also supports backups, imports from other authenticator apps and biometric or PIN protection.

What changed in 1.3.9

The 1.3.9 release updates core libraries and translations. Earlier 1.3.x releases in 2026 also included QR-scanning fixes, performance improvements for large TOTP collections and biometric-unlock changes.

Important F-Droid anti-feature notes

F-Droid currently marks Proton Authenticator with two anti-feature disclosures. First, optional online functionality depends on a proprietary backend. Second, F-Droid states that users are fingerprinted even when online features are not used.

These notes do not change the app’s GPLv3+ source license, but they are important for users who specifically choose F-Droid software to minimize proprietary network dependencies or tracking.

Proton Authenticator vs Aegis

Both are open-source Android authenticators, but their models differ. Aegis is strongly local-vault oriented, while Proton Authenticator offers optional cross-device encrypted synchronization through Proton infrastructure.

See our Aegis Authenticator APK 3.4.3 direct-download guide for the local-vault alternative.

Backup considerations

Authenticator data is critical account-recovery material. Before changing apps or devices, verify that exports, backups or recovery codes are available. Losing the only copy of a TOTP secret can lock the user out of an account even if the authenticator app itself is open source.

Source

Proton Authenticator on F-Droid

Bottom line

Proton Authenticator 1.3.9 is a useful direct-download topic for users who want an open-source 2FA app with optional encrypted multi-device sync. SSM Apps also discloses F-Droid’s backend/tracking anti-feature notes rather than presenting the package as fully offline in every mode.