Provide a master password and this app will create a unique, per-site password. None of the data you enter is stored anywhere outside your device. In fact, none of the data is even stored on your device at all.
For the cryptography nerds among you:
The password is derived using PBKDF2-SHA256, where your master password is the salt and the site or email address is the key. The derived keys data is transformed into a more or less readable string of characters which make up your site-specific password.