The best open source alternative to 2FA Authenticator (2FAS) is Aegis Authenticator. If that doesn't suit you, our users have ranked more than 25 alternatives to 2FA Authenticator (2FAS) and 16 is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to 2FA Authenticator (2FAS) are andOTP (Free, Open Source), FreeOTP (Free, Open Source), Nitrokey (Free, Open Source) and FreeOTP+ (fork of FreeOTP) (Free, Open Source).
FreeOTP is a two-factor authentication application for systems utilizing one-time password protocols with support for Android (3.0 or later) and iOS (7 or later). Tokens can be added easily by scanning a QR-code or by manually entering in the token configuration.
FreeOTP vs 2FA Authenticator (2FAS) opinions
pros, cons and recent comments
Needed a FOSS alternative to the Google Authenticator app to access my company's corporate G-suite instance. This is a simple app and works like a charm!
Nitrokey is an USB key to enable highly secure encryption and signing of emails and data, as well as login to the Web, networks and computers. Other than ordinary software solutions, the secret keys are always stored securely inside the Nitrokey.
Authenticator is a simple, free, and open source two-factor authentication app. It helps keep your online accounts secure by generating unique one-time passwords, which you use in combination with your other passwords to log into supporting websites.
Authenticator Pro generates Two Factor Authentication (2FA) codes for your online accounts. TOTP, HOTP, mOTP (Mobile-OTP) and Steam are supported. The generated codes are one time tokens that provide an extra layer of security to your online accounts.
GTK+ application for securely managing TOTP & HOTP tokens. Content is encrypted on disk using AES256-GCM. Master password derived using PBKDF2 with 100k iterations & SHA512 as hash algorithm. Can import encrypted backups from andOTP & Authenticator+.