FreeOTP+ is an free and open-sourced 2FA autenticator forked from the original FreeOTP with additional feature to help backup, restore and interoperate with other OTP authentication clients.

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.
6. Dark theme support
7. Search token

Source code: https://github.com/helloworld1/FreeOTPPlus
Original FreeOTP:  here: https://play.google.com/store/apps/details?id=org.fedorahosted.freeotp&hl=en

The free and open-sourced Authenticator replacement for 2FA in popular services.