Hi,
I have created a basic debug viewer for Bullet while working on my game engine.
It uses three.js to render debug lines, and communicates to the application (i.e. server) via web socket.

Link: bullet-visualization

Included in the repo is some reference code for creating the server (C++) using the net11 library (details on github).
For now, it can only draw debug lines (no contact points or text).

It might be useful for de-coupling in game rendering and debug draw.

The project is MIT licensed and contributions are very welcome ☺️.