Spatial SQL sandbox

Kyle Walker’s #SpatialSQL Explorer is a clever web app that lets you run spatial #SQL queries on #GeoJSON files directly in your browser using #DuckDB-#Wasm and #MapLibre. Upload WGS84 data (demo or your own), write queries with functions like ST_Touches() or ST_Centroid(), and watch the map and table update live as you explore.
Author

Ralph Straumann

Published

February 19, 2026

From Kyle Walker comes an interesting web app: Kyle’s “Spatial SQL Explorer” can be used to explore a demo GeoJSON file or one of your choosing using Spatial SQL queries.

Spatial SQL Explorer: Test using Swiss municipality borders (Swisstopo) in GeoJSON format from Roman Karavia

The app is built using DuckDB-Wasm1 and MapLibre. It ingests standard GeoJSON files. Only data in WGS1984 is accepted2. Both the map and the tabular display is updated in real time as your SQL query is executed.

Footnotes

  1. “Wasm” stands for “WebAssembly”. While Wasm is also usable in non-web environments, its main goal is to facilitate high-performance applications on web pages.↩︎

  2. Or more precisely: data having expected min/max values for longitude and latitude. GeoJSON files have no Coordinate Reference System (CRS) information, so the app cannot be sure about the actual CRS.↩︎