For anyone who is willing to use a webapp, I like drawio[0]. You can download locally[1] and self host (I just use the python webserver).

While finding the Github, I see they now actually package an Electron application, so that is probably worth exploring[2].

[0] https://www.drawio.com/

[1] https://github.com/jgraph/drawio

[2] https://github.com/jgraph/drawio-desktop

DrawIO feature to save editable PNGs (embedded diagram source code) is absolutely magical.

The tool is quite basic, until you realize, you can create reusable blocks (in scratchpad) with predifened style.

From that point on you just publish editable PNGs to git and draw them rather quickly by dropping in predefined blocks.

One way would be to use emacs’ artist-mode to draw ascii lines and boxes then use ditaa[1] to transform them into images. It’s not a pretty packaged GUI app but it’s certainly an option

[1] https://ditaa.sourceforge.net/

Fairly new and barebones for now, but it is available as a flatpak: https://github.com/Nokse22/ascii-draw

emacs artist mode also suitable for something like that

https://www.youtube.com/watch?v=1JZ6ljIRGus

Also not native, but huydotnet mentioned this in another comment and it looks great https://github.com/tuanchauict/MonoSketch

I've been using PlantUML, having come from using GraphViz.

I can't tell is has any relation to this. I use it to generate SVGs in Maven documentation site builds.

https://asciiflow.com/#/ works pretty well.

get gramscii and aamath