I’ve used Dia for years, great simple tool for diagramming & if I need something more I’ll switch to graphviz dot files
Inkscape works well for this.
Maybe mermaid fits your use case?
See also Inkscape.
Doesn’t quite fit OPs want of self hosted, but still very good.
There is also Asymptote and tikz for more technical stuff.
Draw.io has a Docker container
I used to use one years ago called yEd graph editor. Supremely amazing. It is free to use, but I don’t think it’s open source.
You are aware that draw.io is itself open source and self-hostable: https://github.com/jgraph/drawio ?
“This project is not an open source project as a result.”
https://github.com/jgraph/drawio/blame/dev/LICENSE <-- that’s … a rather specific and recent change. Is there a story here ?
Weird because gliffy (or whatever it’s called) exists on confluence
By no means the best option, but the tikz latex package works and pandoc can handle the conversion to your preferred format. I would limit this to very simple diagrams.
Unless I misunderstand your question, draw.io can be downloaded as a standalone Linux application and run locally.
Likewise, the Xfig package should he available in most Linux repos. It’s old, but good enough for a quick sketch.
edit: aha. My mistake. My eyes slid over ‘open source’ in the title*, and even still I hadn’t realized it was an Apache license.
* Whaaat, it was pre-coffee? Let the purest among us cast the first stone.
draw .io is closed source.
