OpenID

OpenID is an open standard that describes how users can be authenticated in a decentralized manner, eliminating the need for services to provide their own ad hoc systems and allowing users to consolidate their digital identities.

Free Open Source Web

OAuth

OAuth is an open standard for authorization. It allows users to share their private resources (e.g.

Free Open Source Web

Persona

Persona (formerly BrowserID) allows you to sign in to sites using an email address you choose.

Free Open Source Web

Portier

Portier (pronounced "Por-tee-ay") is a self-hostable login service that you can use instead of passwords.

Free Open Source Web Self-Hosted

myOpenID

Janrain Engage (formerly RPX) enables you to quickly register and login users on your site via their existing Facebook, Google, Yahoo, Twitter, or OpenID accounts....

Free Web

Twitter connect

Place a button on your site or application which allows Twitter users to enjoy the benefits of a registered user account in as little as one click. Works on websites...

Free Web

Facebook Connect

Facebook Connect is a set of APIs from Facebook that enable Facebook members to log onto third-party websites, applications, mobile devices and gaming systems with their...

Free Web