GridLook: A browser-based ESM data-viewer

Earth System Models (ESMs) produce output on a wide range of structured and unstructured grids. However, exploring these heterogeneous datasets remains challenging, often requiring specialized software, access to high-performance computing resources, or time-consuming regridding to regular latitude-longitude grids that can introduce interpolation artifacts.

We present GridLook, an open-source, browser-based WebGL visualization tool that enables interactive exploration of cloud-hosted Zarr datasets directly on their native grids without any software installation. GridLook leverages the Pangeo ecosystem by consuming Zarr stores from any CORS-enabled cloud storage (including S3, Swift, and Google Cloud), making it immediately compatible with FAIR data principles and cloud-native workflows.

Key features include: (1) client-side GPU rendering; (2) automatic grid type detection from CF-compliant metadata, supporting a wide variety of grids; and (3) shareable URLs that encode the complete visualization state including dataset location, variable selection, and view parameters.

The architecture follows a serverless design in which all rendering occurs in the user’s browser, removing the need for backend infrastructure and enabling real-time interaction with large datasets through Zarr's chunked access patterns. By combining cloud-native data formats (Zarr), standardized metadata conventions (CF), and modern web technologies (WebGL), GridLook reduces time-to-plot and supports lightweight, shareable visualization workflows. This facilitates rapid visual inspection of model output by both data users and model developers, enabling quicker communication of spatial features and identification of potential bugs during model development.

The tool is freely available at https://gridlook.pages.dev with source code on GitHub, and we invite community contributions for additional grid types and features.