UML Diagram Generator
A friend of mine and I felt like all we were doing in our computer science classes was making UML class diagrams. So we decided to write some code that could be placed inside of any Visual Studio solution and generate an XML file that could be uploaded to draw.io All we then had to do ourselves was to draw some lines and arrows and the diagram was finished.
The code itself is nothing special. It is just under 1000 lines and uses reflection to analyze the code structure. The hard part was to reverse engineer and understand the format draw.io use.