Sonarr/Radarr/Lidarr/Readarr are all open source CRUD apps written in C# (they all fork from Sonarr). Kavita (my open source) app is open source C#/ASP.NET (but

Sonarr/Radarr/Lidarr/Readarr are all open source CRUD apps written in C# (they all fork from Sonarr). Kavita (my open source) app is open source C#/ASP.NET (but probably not a good learning source as I coded while I learned). But CRUD in general are less popular in Open Source as it has to usually be bundled around some self-hosted app. I think libraries and frameworks are far more common.