The author explicitly discusses requirements:

> You don't need to download any dependencies such as plantUML or Graphviz, which is what most of the tools out there require and what was also my motivation to start this project. go-uml is using a 2D graphics engine written 100% in Go https://github.com/fogleman/gg

This is not a solution for these requirements.

Wait, they ask for your api key and they promise not to store it !

Other OpenAI-based projects does that too, and there's an option to not provide your API key as well https://chatuml.com/early-bird