Matthias Pfefferle

Will Norris

OpenID is an <a href="http://openid.net/" rel="nofollow ugc">open standard</a> that allows users to authenticate to websites without having to create a new password. This plugin allows users to login to their local WordPress account using an OpenID, as well as enabling commenters to leave authenticated comments with OpenID. The plugin also includes an OpenID provider, enabling users to login to OpenID-enabled sites using their own personal WordPress account. <a href="https://wordpress.org/plugins/xrds-simple/" rel="ugc">XRDS-Simple</a> is required for the OpenID Provider and some features of the OpenID Consumer.
Developer documentation, which includes all of the public methods and hooks for integrating with and extending the plugin, can be found <a href="http://wiki.diso-project.org/wordpress-openid-api" rel="nofollow ugc">here</a>.

OpenID

Allows WordPress to provide and consumer OpenIDs for authentication of users and comments.

alexisabarca

With this very simple plugin you can use the blog URL to authenticate with OpenID using an another OpenID provider. 
called Delegation.
In order to maximize performance the vars are contained in plugin file rather than storing in a database.
Due to security issue (https://wordpress.org/news/2011/06/passwords-reset/) php file is gpg signed, ID 7ED1BC0C.

Open ID Delegate

This plugin adds the necessary tags to be able to use your blog URL as OpenID address using another OpenID provider

OpenID vs Open ID Delegate