andOTP - andOTP is a two-factor authentication App for Android 4.4+
Auth0 - Auth0 is a program for people to get authentication and authorization services for their own business use.
Aegis Authenticator - Aegis Authenticator is a free, secure and open source app to manage your 2-step verification tokens...
Firebase Authentication - Application and Data, Application Utilities, and User Management and Authentication
OTP Auth - The app for calculating one-time-passwords on iPhone and iPad.
OmniAuth - OmniAuth is a flexible authentication system utilizing Rack middleware.