Excalidraw

An infinite drawing canvas in the browser in which every shape, arrow and text looks like a pen sketch. It works offline, autosaves in the browser, allows real-time collaboration with end-to-end encryption and exports to PNG and SVG. Engineers use it for a first concept sketch, a quick system diagram or an explanation during a video call. It can also be self-hosted on an internal server. It is not a tool for accurate, to-scale drawing.