Yubico provides developers with the Yubico OTP Validation Server and the Yubico U2F Validation Server to enable rapid integration of the YubiKey functionality into an existing web site or service.
Included is free open source software with the required source code and tools for web API clients, validation servers, and libraries. The validation software is offered as components for developers to integrate into any software or system.
The YubiKey Validation Server (yubikey-val) is a server that validates Yubico One-Time Passwords (OTPs). It is written in PHP, for use behind web servers such as Apache. The Yubico OTP Validation Server requires a SQL database.