keyring

Keyring is an authentication framework for WordPress. It comes with definitions for a variety of HTTP Basic, OAuth1 and OAuth2 web services. Use it as a common foundation for working with other web services from within WordPress code. Maintained by beaulebens on GitHub, where it has earned 81 stars from the community.

It's actively developed around 500px, authentication, eventbrite, and is a solid reference for anyone building with these tools.