Plantuml

General Stuff

Scale rendering: scale For example to make the rendering 50% larger, add scale 1.5 to the top.

Class Diagrams

Lucid chart class diagram tutorial on YouTube

Class diagram docs

With Emacs’ org-mode

Plantuml with org-mode

Alternative Diagramming tools

Excalidraw

https://github.com/excalidraw/excalidraw

Free and open source
Can run locally using their docker image