To use indieauth.com as an OpenID delegate for the OpenID identifier of your site, add the following two link tags to the HTML (inside the <head> element) of your website, replacing "example.com" with your domain.
<link rel="openid.delegate" href="https://example.com/" /> <link rel="openid.server" href="https://openid.indieauth.com/openid" />
Follow the setup instructions to set up one or more login provider for indieauth.com. (indieauth.com does not provide its own accounts, instead it relies on you having accounts at other providers.)
To use Twitter as your login provider, simply add a link like the following to your home page.
<a href="https://twitter.com/aaronpk" rel="me">@aaronpk on Twitter</a>
Additionally, you can avoid needing an account with a third party by using either the email or PGP providers.
<link rel="pgpkey" href="/key.txt"> <a href="mailto:email@example.com" rel="me">firstname.lastname@example.org</a>
Try signing in on a website that supports OpenID! The website will discover your OpenID server (indieauth.com) and redirect you here. You'll be presented with a challenge to authenticate using one of the providers you've configured.