Trin.Net.UPnP is a simple UPnP library for the .NET platform. It is built on .NET 5 with no additional dependencies meaning it is completely cross-platform compatible. The original name for this project was UwUPnP.
This was originally based on UPnPLib which was a C# port of WaifUPnP for Java. At this point though, basically all the orginal code has been rewritten from scratch. Even most of the core stuff was completely replaced to make it cleaner and safer to use while also having more functionality.
My main reference for this project was WANIPConnection:1 Service Template Version 1.01, the UPnP standardization documents.
Trin.Net.UPnP Tester, as the name suggests, is a simple testing class for Trin.Net.UPnP.
tPnP is a set of wrappers for Trin.Net.UPnP that allow it to replicate the functionality of NATUPNPLib in Terraria (for use in tML).