Excalidraw is a simple but powerful online drawing tool that our teams enjoy using. Sometimes teams just need a quick picture instead of a formal diagram, for remote teams Excalidraw provides a quick way to create and share diagrams. Our teams also like the "lo-fi" look of the diagrams it can produce, which is reminiscent of the whiteboard diagrams they would have produced when co-located. One caveat: you need to pay attention to the default security — at the time of writing, anyone who has the link can see the diagram. A paid-for version provides further authentication.