The PHP OpenID library implements the OpenID
decentralized identity system. It can be used to
enable single-sign-on across Web applications. The
library includes examples and different options
for storage back-ends.
PHP OpenID Standalone Server functions as a
standalone OpenID server and supports Yadis
service discovery, the Simple Registration
Extension, and admin-controlled or public account
creation. MySQL and the JanRain PHP OpenID library
are required.