Authenticator API.com is an unofficial API for Google Authenticator. Google Authenticator is the defacto-standard in app-based two factor authentication (2FA). If developers would like to add two factor authentication to your application, without using costly SMS messages, use this API to integrate with the Google Authenticator App, without writing the complex crypto code required to do so from scratch.
To use the google authenticator, pair an app with a user's google authenticator app via a QR code, that developers can generate via the "Pair" API call. Once this is done, ask for the user's pin, and validate it against the "Validate" API call.