Excalidraw
Stub: This article needs expansion.
Excalidraw is a whiteboard tool that lets you easily sketch diagrams that have a hand-drawn feel to them.
Our supporter alfredoangeles has started a library of sketchy architectural objects.
As this time (Maj 2021) Excalidraw does not support importing images. Keep an eye on the Import images issue to see how they’re going with that.

See also
- First Draft is a similar online whiteboard tool.
- Getting started with 2D CAD drafting