GeoJSON Map Viewer
- ID
- 20487
- Status
- summarized
- Published
- 02 Sep 2026, 2:05 AM
- Fetched
- 02 Sep 2026, 2:44 PM
- Provider
- Simon Willison
- Category
- developer-ai
- Original URL
- https://simonwillison.net/2026/Sep/1/geojson/
- Source URL
- https://simonwillison.net/atom/everything/
Summary
- Score
- 6.0
- Created
- 02 Sep 2026, 2:45 PM
- Tags
- Audience
- developersvibe_codersai_agent_users
What happened
Simon Willison built a GeoJSON Map Viewer that lets you paste GeoJSON objects (Feature, FeatureCollection, or Geometry) onto an interactive OpenStreetMap with adjustable fill color and opacity, then export as PNG. The tool was iterated using GPT-5.6-Sol, Claude Code for web, and Fable 5.1. He also notes that ChatGPT Work can assemble GeoJSON boundary polygons from government data sources on request.
Why it matters
If you work with geospatial boundaries (e.g., local council or district polygons), you can now ask ChatGPT Work to generate the GeoJSON directly and paste it into this viewer for quick visualization and PNG export—useful for anyone building maps of Malaysian administrative boundaries or community districts without writing custom rendering code.
Discussion angle
The workflow of asking an LLM to assemble GeoJSON from scattered government data sources and then piping it into a purpose-built viewer—how reliable is this for Malaysian boundary data, and where does it break?