Selfauth is a self-hosted Authorization Endpoint used to login with a personal URL (as Web sign-in) via IndieAuth.
Requires only two files in a subdirectory, index.php and config.php. Does not require a database, writes its own config file. Then hide a link like this in your site's <head></head> block:
<link rel="authorization_endpoint" href="https://example.com/auth/" />
When logging into a site that supports it, your username is the URL of your website (https://example.com/) and your password is the password you gave when you set up selfauth.