We use PlantUML with markdown in our internal wiki. The pros are a) that you can understand the markdown on its own, b) we can diff changes to the diagrams, and

We use PlantUML with markdown in our internal wiki. The pros are a) that you can understand the markdown on its own, b) we can diff changes to the diagrams, and c) the source code is very small. The main downside is people are more used to drawing than coding diagrams (even developers), and the output quality of PlantUML leaves a LOT to be desired, by today's standards.