Tofu

An easy-to-use, open-source two-factor authentication app designed specifically for iOS.

Tofu generates one-time passwords to help you protect your online accounts. These passwords are used together with your normal password when you sign into services like Google, Facebook, Dropbox, Amazon, and GitHub.

Tofu works with all services that provide two-factor authentication using the HOTP and TOTP algorithms. It does not require a network or cellular connection and can be used in airplane mode.