GraphViz

A good general purpose graphing language. Easy to use! I recommend installing via Chocolatey on Windows or Homebrew on Mac. Check out their extensive examples page. The examples include source code to get you started.

Diagrams

A diagramming tool where you specify diagrams in Python to create system-level diagrams. Great for describing the overall structure of a system, though possibly a bit too specific to cloud-based software for some uses. Needs GraphViz installed to function.

JS Sequence Diagrams

This is a super cool tool. It’s limited to one type of diagram, but it does that one type of diagram well and I believe it to be a very useful diagram for our purposes. I highly recommend thinking about your particular systems in terms of interactions as sequence diagrams.

Visio (Accessible via IU Anywhere)

I don’t particularly recommend this, but you can get access a copy of Visio running through Citrix (remote) via IU Anywhere. It’s a fairly friendly point-and-click diagramming tool that Microsoft doesn’t really push any longer.

Star UML

Star UML seems to have a fully functional demo that you may find to be pleasing.

ArgoUML

ArgoUML is an open source solution that is a bit rough around the edges, but does a good job.

Gliffy Diagram Generator

Gliffy is a paid product for exporting images. A screenshot of your diagram in the UI is sufficient, but use this only if you can’t get another tool to work well.

Web Sequence Diagrams

This is a tool similar to JS Sequence diagrams. It works well, but I see little reason to use it over the JS version.