I do not know why not more services use it but i want to point out that the Google Authenticator app is just an implementation of [0]HOTP and [1]TOTP. There is

I do not know why not more services use it but i want to point out that the Google Authenticator app is just an implementation of [0]HOTP and [1]TOTP. There is also a free implementation of the same feature set available called [2]FreeOTP. [0] https://tools.ietf.org/html/rfc4226 https://tools.ietf.org/html/rfc4226 [1] https://tools.ietf.org/html/rfc6238 https://tools.ietf.org/html/rfc6238 [2] https://fedorahosted.org/freeotp/ https://fedorahosted.org/freeotp/