Authentication Test allows an easy way for developers to test their automated login scripts against a variety of challanges. Assuming successful login, the top right of the page will turn to a "Log out" login (without XSRF token for easy scripting).
There are also various challanges, such as using session hijacking and rotating codes that help developers understand how to script around XSRF tokens, or in the case of manual intervention (CAPTCHAs/MFA) how to deal with those processes.
This site was built because I work with authentication, and it would be helpful to test a variety of authentication techniques against known-good configurations.