Question: I have a backend system developed with C# .NET 4.0. I wish to embed the light weight web server Kestrel on it. Has anyone done so? or can point me to a direction how to do such?

Cheers!

Answer: 
[**KestrelHttpServer** : "A cross platform web server for ASP.NET ***Core***."](https://github.com/aspnet/KestrelHttpServer). (emphasis added by me).

So that's no, and no.
I did it, but of course only by opening Kestrel which serves a .net core application as a background process. The .Net Framework app communicates with the .net core app via inter-process communication over a websocket on localhost.