Curated list of solutions:

  - excalidraw - https://github.com/alswl/excalidraw-collaboration
  - revezone - excalidraw + tldraw - https://github.com/revezone/revezone
  - code2flow - code - https://app.code2flow.com
  - zenuml - code - https://app.zenuml.com
  - bpmn sketch miner - https://www.bpmn-sketch-miner.ai/examples/syntax-0-00-overview.html
  - d2lang - https://play.d2lang.com
  - mermaid - https://mermaid.live
  - diagram.codes - https://www.diagram.codes
  - kroki - https://kroki.io
  - nomnoml - https://www.nomnoml.com
  - azimutt - db, paid - https://azimutt.app
  - drakon - https://drakonhub.com/try-me
  - svgbob - https://ivanceras.github.io/svgbob-editor
  - typograms - https://code.sgo.to/typograms
  - argdown - for argumentation - https://argdown.org
  - flowchart.fun - paid - https://flowchart.fun
  - penrose - advanced, general - https://penrose.cs.cmu.edu
  - structurizr - https://structurizr.com/dsl
  - state machine cat - https://state-machine-cat.js.org
  - drawthe - http://go.drawthe.net
  - swimlanes.io - https://swimlanes.io
  - js-sequence-diagrams - https://bramp.github.io/js-sequence-diagrams
  - dbdiagram.io - https://dbdiagram.io/d
  - quickdbdiagrams.com - https://app.quickdatabasediagrams.com
  - edotor - https://edotor.net
  - pikchr - https://pikchr.org

Did some research, I'm working on my own diagramming solution for software design.

I quite like https://diagrams.mingrammer.com/