Best Free and Open Source Alternatives to Microsoft Authenticator

Microsoft’s stance for decades was that community creation and sharing of communal code (later to be known as free and open source software) represented a direct attack on their business. Their battle with Linux stretches back many years. Back in 2001, former Microsoft CEO Steve Ballmer famously tarnished Linux “a cancer that attaches itself in an intellectual property sense to everything it touches”. Microsoft also initiated its “Get the Facts” marketing campaign from mid-2003, which specifically criticized Linux server usage, total cost of ownership, security, indemnification and reliability. The campaign was widely criticized for spreading misinformation.

However, in recent years, there has been a partial shift by Microsoft to embrace the open source software paradigm.

This series looks at the best free and open source alternatives to products and services offered by Microsoft.

Microsoft Authenticator is a mobile authentication app for Android and iOS. It can generate one-time passwords for two-factor authentication and also supports Microsoft’s own passwordless and approval-based sign-in mechanisms.

For standard two-factor authentication, there are some excellent open source alternatives. They generate the time-based or HMAC-based one-time passwords used by thousands of websites and online services.

These alternatives cannot necessarily replace Microsoft Authenticator when an organisation specifically requires Microsoft’s push notifications or passwordless authentication. For standard TOTP/HOTP authentication, however, they are excellent replacements.

1. Aegis Authenticator

Aegis Authenticator is a secure and polished two-factor authentication app for Android.

It supports both HOTP and TOTP and stores authentication tokens in an encrypted vault. The vault can be protected using a password or biometrics. Other useful features include encrypted backups, automatic backups, entry grouping, custom icons and multiple ways to import existing authentication tokens.

Aegis can import data from numerous competing authenticator apps, including Microsoft Authenticator, Google Authenticator, 2FAS Authenticator, FreeOTP and others.

The software is released under the GNU General Public License v3.0.

2FAS Auth

2FAS Auth is a free and open source authenticator available for Android and iOS.

It supports TOTP and HOTP and does not require an account. Authentication tokens are stored locally, while users who want backup and synchronisation can use their own Google Drive or iCloud storage. Manual backups are also supported.

One particularly attractive feature is its browser extension. This lets users approve authentication requests from their phone rather than manually copying six-digit codes into the browser. Communication between the extension and mobile device is end-to-end encrypted.

The Android application is licensed under the GNU General Public License v3.0.

3. Ente Auth

Ente Auth is a cross-platform two-factor authenticator with end-to-end encrypted backups and synchronisation.

Unlike many authenticator apps, Ente Auth is not restricted to smartphones. It is available for Android and iOS together with Linux, macOS, Windows and the web. Authentication codes can therefore be accessed across multiple devices while remaining end-to-end encrypted.

The software can also operate without an account for users who prefer an offline authenticator. Tokens can be added by scanning a QR code, entering a secret manually, or importing them in bulk from another authenticator.

Ente Auth also supports encrypted and plaintext exports, helping users avoid being locked into the application. The project is fully open source and is licensed under the GNU Affero General Public License v3.0.

All articles in this series:

Alternatives to Microsoft's Products and Services
	Authenticator is a mobile authentication app for Android and iOS. It can generate one-time passwords for two-factor authentication and also supports Microsoft’s own passwordless and approval-based sign-in mechanisms.
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