Zarr Python

When to use

Use for chunked scientific arrays, hierarchical stores, codecs, sharding, partial reads, cloud object storage, and NumPy/Dask/Xarray interoperability. This community guide targets Zarr-Python 3.4.0, released 2026-09-15, with Python 3.12+. The package version and on-disk format are separate: this release reads/writes formats 2 and 3; new arrays default to format 3. Keep downstream packages that require zarr<3 in their own environments.

Install

uv pip install "zarr==3.4.0" "numpy==2.5.3"
# Optional remote backends and migration CLI:
uv pip install "zarr[remote,cli]==3.4.0" "fsspec==2026.9.0" "s3fs==2026.9.0" "gcsfs==2026.8.1"