As far as I can tell, https://excalidraw.com/ is already possible to use offline, since it seems to be a PWA.

Just a friendly reminder that "web !== requiring internet 24/7 internet connectivity", many client-side applications works even if you go offline, granted you have loaded the page at least once before.

Try loading the page, disconnecting your internet and then doing a hard-refresh/reload your browser.

You can install it as PWA app both on your mobile (added to your home screen) or desktop that works offline :).

Excalidraw is a PWA, so you should be able to install it as an app on your local machine and use it off line.

I haven't tested it rigorously but it appears to work seamlessly when offline.

I use the pwa