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Compatibility status tracking

This page tracks the status of packages for which we're aware of active work on free-threaded support. It contains packages with extension modules, as well as build tools and packages that needed code specifically to support free-threading. Note that pure Python code works without changes by design, hence this page does not aim to track pure Python packages.

If there's a bug related to free-threading in a library you use, please open an issue on the corresponding issue tracker or post a comment on the corresponding free-threading support tracking issue (see table below). If an issue spans multiple projects or there's an ecosystem-wide point to discuss, please open an issue on this issue tracker.

Tip

It's early days for free-threaded support - bugs in CPython itself and in widely used libraries with extension modules are being fixed every week. It may be useful to use nightly wheels (when available) of packages like cython or numpy, even if a first release is available on PyPI. For example, you can install a NumPy nightly wheel by running:

pip install -i https://pypi.anaconda.org/scientific-python-nightly-wheels/simple numpy
Project Upstream issue Tested in CI PyPI release First version with support Nightly wheels Nightly link
cffi 1.18
cibuildwheel 2.19
CMake 3.30.0 1
ContourPy 1.3.0
Cython 3.1.0
joblib 1.4.2
matplotlib 3.9.0
Meson 1.5.0
meson-python 0.16.0
multidict
mypyc
Nuitka
NumPy 2.1.0
nanobind 2.2.0
packaging 24.0
pandas 2.2.3
Pillow 11.0.0
pip 24.1
PyArrow 18.0.0
pybind11 2.13
PyO3 N/A 0.22.2 N/A N/A
PyWavelets 1.7.0
scikit-build-core 0.9.5
scikit-image
scikit-learn 1.6.0
SciPy 1.15.0
setuptools 69.5.0
wrapt 1.17.0.dev3
zstandard

  1. Windows isn't correctly handled yet in CMake 3.30.0, see cmake#26016