Implementations

GeoZarr conventions advance in maturity through diverse implementations. The Zarr Conventions Framework requires 3+ independent implementations for Candidate maturity.

Implementation Matrix

Implementation	Language	proj	spatial	multiscales	Notes
eopf data-model	Python	Full	Full	Full	Reference implementation for EOPF Sentinel data
zarr-cm	Python	Full	Full	Full	Zero-dependency conventions metadata library
GDAL	C++	Full	Full	Full	Read/write in 3.13; GEOREFERENCING_CONVENTION=SPATIAL_PROJ option
rioxarray	Python	Full (Write TBR)	Full (Write TBR)	—	Read/write via Convention.Zarr
geozarr-toolkit	Python	In progress	In progress	In progress	CLI (geozarr validate, geozarr info) and FastAPI service
OpenLayers	JavaScript	Read	Read	Read	ol/source/GeoZarr; experimental; requires ol ≥ 10.8.0
STAC Browser	JavaScript	Read	Read	Read	Browses STAC catalogs; renders GeoZarr assets via OpenLayers (ol-stac)
TiTiler (via EOPF)	Python	Read	Read	Read	GeoZarr Reader
zarr-layer	TypeScript	Read	Read	Read	MapLibre/Mapbox rendering; arbitrary CRS via proj4; v0.4.3
deck.gl-raster	TypeScript	Read	Read	Read	GPU/WebGL2 rendering in deck.gl; own @developmentseed/geozarr parser
QGIS GeoZarr	Python	Read	Read	Read	Plugin with band selection, satellite presets; requires GDAL 3.13

Support levels: Full = read/write, Read = read-only, In progress = under active development

Implementation Details

GDAL

The GDAL Zarr driver (v3.13+) supports read/write of proj, spatial, and multiscales conventions for Zarr V3. Key features include sharded storage, parallel chunk decompression, and BuildOverviews for multiscale pyramid generation. Use the GEOREFERENCING_CONVENTION=SPATIAL_PROJ creation option to write GeoZarr conventions.

• Driver documentation
• GDAL Zarr contributions by wietzesuijker — 20+ PRs for sharding write, shard index caching, parallel decompression, and multiscales support

rioxarray

rioxarray (v0.22+) supports reading and will support writing in next release CRS and transforms using the Zarr proj: and spatial: conventions. Use Convention.Zarr to read/write Zarr conventions alongside or instead of CF conventions.

• GitHub
• Proposal and discussion

eopf data-model

Python library for converting EOPF (Earth Observation Processing Framework) datasets to GeoZarr-compliant format. Supports native CRS preservation, COG-style /2 downsampling for multiscale, CF standard names, and S3 output.

• GitHub
• Documentation
• EOPF Explorer data model page

OpenLayers

The ol/source/GeoZarr source reads GeoZarr groups with multiscales support directly in the browser. Currently experimental (API subject to change).

• Example
• Source code

STAC Browser

Vue.js application for browsing and searching STAC APIs and static catalogs. Renders GeoZarr assets from STAC Items directly in the browser via ol-stac (OpenLayers STAC), which builds on the OpenLayers GeoZarr source (ol/source/GeoZarr).

• Live app
• GitHub
• Example: EOPF Sentinel-2 L2A item
• ol-stac GeoZarr rendering example

zarr-layer

Custom MapLibre/Mapbox layer for rendering Zarr datasets, supporting Zarr v2 and v3, arbitrary CRS reprojection via proj4, multi-band custom shaders, globe rendering, and querying.

• GitHub
• Demo
• Pangeo Showcase presentation

deck.gl-raster

GPU-accelerated (WebGL2) rendering of GeoTIFF, COG, and Zarr in deck.gl, entirely client-side with no server. Its @developmentseed/geozarr package independently parses and validates the spatial, geo-proj, and multiscales conventions — multiscale layout, per-level affine transforms, array shapes, axis labels, and CRS — into a typed GeoZarrMetadata value, with no rendering or I/O dependencies.

• GitHub
• Documentation
• @developmentseed/geozarr metadata package

QGIS GeoZarr

QGIS plugin for loading cloud-native Zarr data from STAC catalogs. Features band and resolution picker with satellite presets (Sentinel-2, Landsat, MODIS, Sentinel-3, EOPF), multiscale pyramid support, and auto RGB styling. Zarr v2 and v3 including sharded stores (sharding requires GDAL 3.13+).

• QGIS Plugin Repository
• GitHub
• Pangeo Showcase: "No shard feelings: GeoZarr rendering in QGIS, powered by GDAL"

Production Deployments

Deployment	Stack	proj	spatial	multiscales	Notes
EOPF Explorer	OpenLayers + TiTiler	Read	Read	Read	First production adoption for Sentinel-2 L2A data; serves sharded Zarr v3 with GeoZarr conventions via STAC catalog

Tools & Libraries

geozarr-toolkit

Python library for creating, validating, and working with GeoZarr metadata. Includes a CLI (geozarr validate, geozarr info) and a FastAPI web service.

• GitHub

geozarr-examples

Reference documentation, Jupyter notebook examples, and example datasets demonstrating GeoZarr conventions in practice.

• Documentation
• GitHub

metazarr

Browser-based tool for exploring Zarr stores and validating GeoZarr conventions against JSON Schemas. Runs entirely client-side.

• GitHub
• Online inspector

zarr-cm

Lightweight Python implementation of Zarr Conventions Metadata.

• GitHub