Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!
PlantUML
PlantUML is a great text to UML tool. It can be used to create flowcharts too.
You can try it online at PlantText . You can download the the reference guide at PlantUML Language Reference Guide .
You can run your own PlantUML server with Docker. Please refer to How to Run the PlantUML Server with Docker for details.
PlantUML for Visual Studio Code
https://marketplace.visualstudio.com/items?itemName=jebbs.plantuml
https://marketplace.visualstudio.com/items?itemName=Mebrahtom.plantumlpreviewer
https://www.freecodecamp.org/news/inserting-uml-in-markdown-using-vscode/