Authenticator — App Store rankings

About this app

The developer's US App Store description, in full.

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. The simple combination of the password in your head and the rotating passwords generated by the app make it much harder for anyone but you to access your accounts. • Easy: Simple setup via QR code, "otpauth://" URL, or manual entry • Secure: All data is stored in encrypted form on the iOS keychain • Compatible: Full support for time-based and counter-based one-time passwords as standardized in RFC 4226 and 6238 • Off the Grid: The app never connects to the internet, and your secret keys never leave your device.