I got a post on Archaic Binary BBS about how to write a BBS door.
Well I am fairly new to this still, and have only written two small 32bit BBS doors that I use on my own system.
Firstly I used a copy of Rick Parrish’s RMLib to write them, it’s not a very complete SDK or anything but it does give the basic IO functions we need for communication over the socket connection.
Then you need a IDE for C#. I suppose one of the best is Microsoft’s Visual Studio 2012 C# Express. It’s free and the project files worked for me.
If you can write in C# then you should be fine.