Well, I did not write the entire thing, it depends on the buttplug project, for all the important stuff.

It essentially allows you to run a mini web server that can be interacted with from Second Life (http requests)

The project is written in c# dotnet core and also includes a couple of LSL examples on how to interface with it.

The sourcecode and documentation can be found here:

https://github.com/kyrahabattoir/ButtplugWebBridge