FreeOTP is a two-factor authentication (2FA) application for systems utilizing one-time password protocols (OTP). Tokens can be added easily by scanning a QR-code or by manually entering in the token configuration.
FreeOTP implements open standards. This means that no proprietary server-side component is necessary: use any server-side component that implements these standards - for example FreeIPA, which uses TOTP. Any standards-compliant implementation will work. Currently, FreeOTP provides implementations of HOTP (RFC 4226) and TOTP (RFC 6238).