Yeah, Excalidraw is really nice diagramming tools that I frequently used as well on my day-to-day works.

For the self-host, finally I build the solution myself so I can self-host Excalidraw and several other plaintext diagramming format while still able to working with my peers using realtime collaboration.

I open sourced it on https://github.com/andes90/collabmd, and if you want to try you can play around with the demo on https://demo.collabmd.app