The free and open-sourced Authenticator replacement for 2FA in popular services.
This is based on the original FreeOTP here: https://play.google.com/store/apps/details?id=org.fedorahosted.freeotp&hl=en
It provides additional feature:
1. Back up the data to Google Drive or other storage
2. Restore data from Google Drive or other storage
3. Material design and updated UI.
4. Android 6.0 on-demand permission support
5. Android 6.0 backup support. After reinstalling, all your saved authentications will come back.
Source code: https://github.com/helloworld1/FreeOTPPlus