I have an app that is growing a little complex, and today I am actually working on graphing the routes and the relations between those pages (breadcrumbs/XHR/redirects/links). It's actually really painful. I'm doing it with Graphviz.
I’m the creator of flowchart.fun which is a quick text-to-diagram tool. If I’m being honest I didn’t use it much when developing stuff at first but of late I find it’s really nice if I have a mental dependency graph that I just want to visualize to help prioritize tasks and think about blockers. Mermaid.live is awesome for this. Anything you can drop into quickly imo
The painful part is mostly collecting the data, inputting it into DOT is not too bad. The result is quickly turning into a hairball though.