~/log/making-and-printing/catprinter-python
Cat printer from the command line
Bluetooth thermal "cat printers" (GT01, GB02, GB03 and similar)
open repo ↗ github.com
- ai
- none documented
- evidence
- public
- reviewed
The roughly $20 thermal “cat printer” from AliExpress only prints through its vendor’s phone app. rbaron reverse-engineered the app’s Bluetooth protocol and wrote a Python script that prints any image straight from Linux or macOS, with a choice of dithering algorithms and print darkness. It finds the printer on its own.
For a printer variant this script doesn’t match, Mertol Kasanan’s write-up shows how to work out the protocol yourself.
- ai
- Reverse-engineered by hand in 2021 from the official Android app. One 2026 contributor fix for macOS carries a Claude Co-Authored-By trailer.
- caveats
- Python command-line tool, no GUI. Cat printers are sold under many names with different internals, so not every one will work. Prints images only; turn text into an image first.
- evidence
- Public code, MIT licence, about 860 stars. Maintained since 2021.
- github
- 862 stars, last commit 2026-05-26. As of 2026-11-15. Stars show interest, not safety.
Code or detailed materials are published. Says nothing about safety, quality or maintenance. Not tested by unshittify. Added by unshittify. Wrong or out of date? Send a correction.