Installation

z4ai requires Python >= 3.9 and depends only on numpy and zstandard.

pip install z4ai

From a checkout of the repository:

pip install .
# or, for development:
pip install -e ".[test]"

Optional extras

Extra	Installs	Enables
z4ai[maxratio]	brotli	the effort="max" high-ratio tier (a chunk-parallel context-modeling backend). z4ai degrades gracefully to the fast default without it.
z4ai[test]	pytest, brotli	the test suite
z4ai[benchmark]	zipnn, brotli	the head-to-head benchmarks in benchmarks/

Optional native acceleration

z4ai ships small C sources (a SIMD byte-shuffle, an interleaved rANS coder, and a fused chunked codec) that are compiled on demand. They are optional - without a C toolchain z4ai runs as pure Python (NumPy + zstandard). To build them ahead of time:

python -m z4ai.build_native

The on-disk frame format is identical with or without the native code, so frames are byte-interoperable between the two.