[lloeki]

Check out https://mermaidjs.github.io which is less visual in plain text but much easier to write.

[desas]

PlantUML is a good alternative too and has a good jetbrains plug-in

[Jach]

I came cross PlantUML recently, it's so much more than a classic diagram tool. I was particularly intrigued by their wireframe system: http://plantuml.com/salt

[psnosignaluk]

As we use Confluence for our collective brain, awareness of this was an unexpected bonus. Thank you.