products

Are you implementing an auth server or integrating with one? Regardless, the last time I dug into this topic I ended up feeling the same. The web is littered with articles that scratch the surface and only cover the basics. They often leave out the details, which IME ended up making things more difficult to understand. What was the most helpful, as you said, was to follow the RFCs and the OIDC spec directly. What might also be useful, if you are implementing an auth server, is to look at existing implementations. Duende IdentityServer (https://github.com/DuendeSoftware/products/tree/main/identit...) is the most widely-used one in the .NET space.

https://github.com/DuendeSoftware/IdentityServer https://github.com/microsoft/calculator if you go on github you can browse C# repositories, there are good examples there https://github.com/topics/csharp

>(still is open source) I think https://en.wikipedia.org/wiki/Source-available_software is more accurate see https://duendesoftware.com/license/identityserver.pdf (as pointed by https://github.com/DuendeSoftware/IdentityServer/blob/main/L... ) for their actual license.

https://github.com/DuendeSoftware/IdentityServer/blob/main/L... does not seem to square with any definition of "open source" I'm familiar with, and that goes double for having an in-repo file that just says "read this unversioned pdf on some other site"

Identity server is still open source, it just has a much more restrictive license and is paid. https://github.com/DuendeSoftware/IdentityServer