Open Source Kotlin Authentication Software

Proton Authenticator for Android is Proton’s official Android implementation of a modern two-factor authentication (2FA) app, designed to generate secure, time-based one-time passwords (TOTPs) and support multi-account authentication workflows with strong privacy and encryption features. The app enables users to link 2FA tokens for their online accounts, scan QR codes, and generate rotating verification codes that enhance login security across services that support TOTP standards. Built with native Android tooling and following modern design conventions, it integrates with Android’s notifications and system UI while maintaining local encryption of stored secrets so that authentication tokens are never exposed in plaintext outside the device. It also supports backup and encrypted sync with the associated Proton account, helping users recover 2FA codes across devices — a feature that many standalone token generators lack without risking security trade-offs.

2FAS Auth for Android is the general Android authenticator client for the 2FAS open-source multi-factor authentication suite, designed to help users protect their online accounts with secure, rotating one-time passwords and optionally manage related vault entries. This client lets users add and view TOTP and HOTP tokens for countless services, restore and backup token sets across devices, and secure the app with passcodes or biometrics. The Android implementation emphasizes straightforward setup and usage, providing an incremental list of codes that update in real time, quick token management, and compatibility with common OTP QR codes. It also supports sync and optional integration with 2FAS browser extensions to autofill or streamline authentication workflows when signing in to services across devices.