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

EMCSSL

Distributed network security infrastructure based on self-signed clients SSL certificates and cryptocurrency blockchain Full description here: http://emercoin.com/EMCSSL .

Free Open Source Windows Linux Mac

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

IndieAuth

IndieAuth is a way to use your own domain name to sign in to websites. It works by linking your website to authentication providers such as Twitter or Google, then...

Free Open Source Web Self-Hosted

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