2FA Locker implements Time-based One-time Passwords (TOTP) like specified in RFC 6238 (HOTP support is currently in beta testing). Simply scan the QR code and login with the generated 6-digit code.

Features:
•  Free and Open-Source
•  Requires minimal permissions:
 •  Camera access for QR code scanning
 •  Storage access for import and export of the database
•  Encrypted storage with two backends:
 •  Android KeyStore (can cause problems, please only use if you absolutely have to)
 •  Password / PIN
•  Multiple backup options:
 •  Plain-text
 •  Password-protected
 •  OpenPGP-encrypted
•  Sleek minimalistic Material Design with three different themes:
 •  Light
 •  Dark
 •  Black (for OLED screens)
•  Great Usability
•  Compatible with Google Authenticator

Backups:
To keep your account information as secure as possible 2FA Locker only stores it in encrypted data files. There are two methods of encryption which can be used: the Android KeyStore or a Password / PIN.

The KeyStore is a system component of Android for securely storing cryptographic keys, the advantage of this approach is that the key is kept separate from the apps data and, as a bonus, can be backed by hardware cryptography (if your device supports this). However, due to that separation, backups with 3rd-party apps like Titanium Backup can not be used if this method is chosen. Such apps only backup the encrypted data files and not the encryption key, which renders them useless. In this case you will have to rely on the internal backup functions provided by 2FA Locker!

The KeyStore is known to cause a lot of problems, so please only use it if you absolutely have to and know what you are doing. In that case please make sure to make regular backups in case something goes wrong. It is always recommended to use a password or PIN instead!