LibGit2Sharp VS openiddict-core

To use it as an API on windows you might want to go with a C# wrapper. libgit2sharp

You might want to leverage something like libgit2 if you store that data in a unique location. After you commit changes to your data, you can find the patch differences in the file. Then store the commit hash and set up communication that wakes up when the hash changes. When the commit hash changes, you send just the patch changes to the clients which can apply them to their local copy.

libgit2sharp to work with git repositories in .NET https://github.com/libgit2/libgit2sharp

Is it something you could possibly achieve with git? - https://github.com/libgit2/libgit2sharp/

Currently, my plan is to use LibGit2Sharp to do almost all the logic, and use System.IO to manage the local files. Problem is: LibGit2Sharp documentation is very sparse and hard to read.

Openiddict is also an option. Check it out.https://github.com/openiddict/openiddict-core

To implement an OAuth server together with OpenID connect specification, I used a free and open source framework called Openiddict. You should checkout their GitHub repository at github.com/openiddict/openiddict-core. It is a nice and feature rich tool which help you get started very fast. However, comparing to alternatives like identity server, it needs more implementation rather functionalities coming out of the box.

You can use Openidict https://documentation.openiddict.com/, give it a try

Openiddict to create your own OpenID Connect server if you want to deep dive into auth https://github.com/openiddict/openiddict-core

If you do want a .NET IdP then you could look into OpenIddict but will require some hands on work, at a minimum authorisation controllers. If you're looking for something more out of the box OrchardCore's OpenId module might be better for you.

I personally prefer using Cookies with openiddict.

Also, the OAuth bit is very cool!! Do you plan to support OpenIddict it’s a free federated identity server.

Okta is a great example of an IdP, although there are many others. Auth0, Ping Federate, Amazon cognito, etc. OP also mentioned Identity Server, which is a framework for implementing your own IdP. I've also personally used an open-source library called [OpenIDDict[(https://documentation.openiddict.com/) to great success. I would highly recommend attempting to implement one of these providers as a learning exercise.