Optional speedup extension

Why?

charset-normalizer will always retain a pure Python implementation, so environments without native build capabilities can use it without additional requirements.

Platform-specific wheels include pre-built Cython extensions for the mess and coherence detectors. The extensions preserve the public Python API while moving their hot loops to C.

When no compatible native wheel is available, charset-normalizer automatically falls back to the pure Python implementation.

How?

If your platform or architecture is not served by a native wheel, you can compile the extensions locally with a C compiler and Python development headers:

export CHARSET_NORMALIZER_USE_CYTHON=1
pip install charset-normalizer --no-binary charset-normalizer

How not to?

You may install charset-normalizer without the extensions by building the source distribution without setting CHARSET_NORMALIZER_USE_CYTHON.

E.g. when installing requests and you don’t want to use the charset-normalizer speedups, you can do:

pip install requests --no-binary charset-normalizer

When installing charset-normalizer by itself, you can also pass :all: as the specifier to --no-binary.

pip install charset-normalizer --no-binary :all: