[dangerboysteve]

nice tool but I'm a fan of draw.io, opensource and can be downloaded to your machine to run locally if wanted.

[tyingq]

This appears to be open source also, and runnable locally: https://github.com/excalidraw/excalidraw

There's a docker image also: https://hub.docker.com/r/excalidraw/excalidraw

It's hard to tell exactly, but it sounds like the "plus" version would just have more collaboration functionality.

[sigzero]

I had no idea that draw.io had a desktop version. Cool.