Kurvengefahr: A browser-based CAD/CAM for pen plotters

Most pen plotter enthusiasts I know struggle with the same massive headache: you finally get the hardware rigged up, but converting your line art into usable G-code feels like a chore from the stone age. I was watching a colleague try to hack together a workflow for a custom plotter attachment recently, and it reminded me of how fragmented this niche is. One person is using a 3D printer as a makeshift plotter (which is a clever bit of jank, honestly), while another is trying to manually script paths.

Then I saw this project, Kurvengefahr, and it’s a completely different beast. It’s a browser-based CAD/CAM tool specifically built for pen plotters. Instead of jumping between three different software packages to import art, clean it up, and then somehow prep it for hardware, this handles the whole pipeline in the browser. It even has these bizarrely cool features like a Logo interpreter for turtle art and a "Graves RNN" for handwriting synthesis (because why not make your plotter write like a human?).

The technical implementation is what caught my eye as someone who deals with deployment workflows. It uses Web Serial to talk directly to hardware. This means it isn't just limited to people "pretending" their 3D printers are plotters; it actually supports real AxiDraw machines (EBB firmware) and GRBL-based plotters.

I’m curious how the latency feels on actual GRBL hardware versus the STM32 mocks the dev used for testing. If you've got an AxiDraw sitting on your desk gathering dust, this might actually be the software that makes it useful again.

The source code and documentation are hosted here:
https://github.com/tibordp/kurvengefahr