Nunchaku
nunchux-aiNunchaku is an inference engine for diffusion models quantized to 4-bit weights and activations with SVDQuant, a low-rank method that keeps image quality close to the full-precision model while cutting memory several times over. It runs INT4 and NVFP4 builds of FLUX.1, Qwen-Image, SANA, Z-Image and PixArt, and plugs into ComfyUI through a companion node pack. It began in MIT HAN Lab.
The PyPI project named nunchaku is an unrelated data-segmentation library; this engine ships as wheels on its GitHub releases, so no package is declared.
Openness
5 high confidence- license
- Apache-2.0(OSI
- source
- public(nunchux-ai/nunchaku)
- core features withheld
- no — no ee, enterprise, commercial or proprietary path
Nunchaku is released under Apache 2.0 with its full source public. Its authors offer consulting and partnership to companies but no separate paid build of the engine.
- https://raw.githubusercontent.com/nunchux-ai/nunchaku/main/LICENCE.txt recorded 2026-09-26
LICENCE.txt body: "Apache License / Version 2.0, January 2004".
- https://raw.githubusercontent.com/nunchux-ai/nunchaku/main/README.md recorded 2026-09-26
README Contact Us: "For enterprises interested in adopting SVDQuant or Nunchaku, including technical consulting, sponsorship opportunities, or partnership inquiries, please contact us"; no paid edition is named.
- https://ungh.cc/repos/nunchux-ai/nunchaku/files/main recorded 2026-09-26
Full file list: no ee/, enterprise/, commercial/ or proprietary/ path; LICENCE.txt is the only license file.
Adoption
2 low confidenceThe engine is distributed as wheels on its GitHub releases, and the PyPI name it would use belongs to an unrelated project, so GitHub stars are the only comparable signal. A star is not a use.
- https://pypi.org/pypi/nunchaku/json recorded 2026-09-26
PyPI nunchaku: "Optimally partitioning data into piece-wise linear segments.", with its repository at git.ecdf.ed.ac.uk, an unrelated project.
- https://ungh.cc/repos/nunchux-ai/nunchaku recorded 2026-09-26
Repository record: stars 3955.
Capability
2 high confidenceNunchaku runs several image model families in 4-bit form, fitting large models such as FLUX.1 onto consumer GPUs. It is a step below stable-diffusion.cpp because it runs image models only, with no video generation.
- https://raw.githubusercontent.com/nunchux-ai/nunchaku/main/README.md recorded 2026-09-26
README: "a high-performance inference engine optimized for 4-bit neural networks"; its news entries name FLUX.1 tools, Kontext and Krea-dev, SANA, Qwen-Image and Qwen-Image-Edit, and Z-Image-Turbo; no video or audio model is named.
Verified 2026-09-26