It implements Time-based One-time Passwords (TOTP) and HMAC-Based One-Time Passwords (HOTP). Simply scan the QR code and login with the generated 6-digit code.
Unmaintained, see https://github.com/andOTP/andOTP and developers announcement on XDA https://forum.xda-developers.com/t/app-4-4-open-source-andotp-open-source-two-factor-authentication-for-android.3636993/post-87021655
Google Authenticator generates 2-step verification codes on your phone.
Enable 2-step verification to protect your account from hijacking by adding another layer of security. With 2-step verification signing in will require a code generated by the Google Authenticator app in add.
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.
Keysmith is a token generator for your two-factor authentication (2FA) logins. It supports time and hash-based one-time passwords (TOTP/HOTP).
2FAS Authenticator is a simple and free application for Two Factor Authentication (2FA Authentication) which generates Time-based One-time Passwords (TOTP) and PUSH authentication*.