Excalidraw is a fairly new (having started in January 2020) virtual whiteboard software for creating diagrams with a hand-drawn aspect.
I really like the aesthetics of diagrams created with Excalidraw. They have a natural feel and elegance to them.
However, when recently revising some of the diagrams for Stratospheric – From Zero to Production with Spring Boot and AWS I found Excalidraw to be lacking shapes for UML & ER diagrams. I know, not everyone is fond of those, but if you keep them simple and don’t overdo it they serve a useful purpose in outlining and explaining software designs.
Excalidraw allows you to easily extend its existing library and their developers are responsive and open to contributions.