A small web tool called GeoJSON Map Viewer was created to render GeoJSON files on a map and export the rendered view as a PNG. The development originated from a practical need to assemble maps for the Granada Community Services District and the Midcoast Community Council.
Beginnings and development
Natalie received help collecting the map materials for those local entities. The initiator asked GPT-5.6-Sol for tool suggestions; the model proactively produced a working solution. That initial build was refined through iterations using Claude Code for web and Fable 5.1, resulting in the current functional tool.
Obtaining GeoJSON boundaries
Many of the required GeoJSON boundaries were obtained with the assistance of ChatGPT Work. Specific requests produced polygons such as the GeoJSON representing the exact boundary of the El Granada GCSD and a GeoJSON for the MCC - Midcoast Community Council that operates near Half Moon Bay, CA. By extracting and combining data from various government sources, the process produced the necessary boundary files.
What the tool does
GeoJSON Map Viewer allows multiple GeoJSON files to be displayed simultaneously on a map and lets the user export the displayed view as a PNG image. This is useful for mapping local administrative boundaries, community councils, and similar territorial units when a static image is needed for documentation or presentations.
Notes
The development illustrates how automated tooling and large language model assistance can be combined to solve practical geospatial tasks. ChatGPT Work was used to pull together and merge data from different government sources to build the GeoJSON files required for the project.
