YubiOTP is a library for verifying YubiKey OTP tokens. It includes both the low-level implementation for verifying tokens locally and clients for multiple versions of the Yubico validation web service. The primary audience is developers who wish to verify YubiKey tokens in their applications, presumably as part of a multi-factor authentication scheme.

For testing and experimenting, the included yubikey script simulates one or more YubiKey devices using a config file. It also includes utility commands such as a modhex converter.

YubiOTP also includes a command-line web service client called yubiclient.