Authenticator is a free app that is designed to generate time-based one-time passwords (TOTP) and push messages for your accounts. It can also generate a QR code for your mobile.

It generates one-time passwords and push messages for your online accounts. The generated codes are time-based tokens. You can use them to secure your online accounts on supporting websites. You only need to enter a secret key for authentication. The secret key is a piece of information that you know and remember.

If you don't know the secret key, you can either use the QR code or manually enter it.