CollabUML is a PlantUML based app for online collaborative design on UML
CollabUML is a super-simple client only app that wires existing technology, in this case, it uses an https://etherpad.org to handle the collaborative text editor and https://plantuml.com/ public server to render the editor's content.
There is a timer that takes the etherpad content to render it with plantuml on every tick.
An Etherpad instance is required, host/apikey must be configured at config.js
Then, run npm install to download the js dependencies, then, npm run start will allow you to use the app at localhost:8080
The project was created in 2020, there haven't been much changes since then, I plan to keep the server running for as long as it doesn't require much maintenance (the case for 3 years).