One of the building blocks of the Indieweb is IndieAuth. Like many others, I bootstrapped my experience with indieauth.com but as Marty McGuire explains, there are good reasons to switch and even consider building your own. Because I wanted a server as simple to understand as possible but also wanted to be able to add features that are usually not available, I created a rails project called Irwin and recently configured my blog to use it.
This is not production ready code. While I know that the micropub server I use works with it, I expect others may not. Also, there is no support for refresh tokens and other things in the spec that I didn’t consider high priority. It does support PKCE but not the less useful “plain” method.
All of IndieAuth Spec Updates 2020 was very clear and helpful. In one case, I made the server probably too strict (as an easy way to curtail spam registrations). It requires that the hosts for a blog’s authorization endpoint and token endpoint match the host of the IndieAuth server before a user can register an account on the indieauth server.
I plan to add an option for a user to keep a history of logins to indieauth clients soon. Please let me know if you have any questions or suggestions.