Just for fun, I'm writing an internet forum software from scratch, strongly inspired by phpBB and the likes.
It is split into an Angular UI, C# ASP.NET Core RESTful API and postgres database. I aimed to let EF Core handle the data model in the database and am pleasantly surprised by how well it works. Also updating the database is a breeze with its migrations.
The features of a forum seem easy enough, but I find it difficult to detail it out into the data model at times.