What Is TopoJSON?
TopoJSON is an extension of GeoJSON that encodes geographic topology using shared arcs rather than duplicate coordinate arrays. By storing boundaries only once, TopoJSON files are typically 80% smaller than their GeoJSON equivalents while preserving all geometry information.
This is used for:
- Web Map Optimization: Reduce map loading times by serving TopoJSON, then converting to GeoJSON on the client for rendering.
- Data Compression: Archive large geographic datasets in TopoJSON format to save storage space and bandwidth.
- Interoperability: Convert TopoJSON from data portals or D3.js visualizations into plain GeoJSON for use in tools that don't support TopoJSON natively.
How to Use the TopoJSON to GeoJSON Converter Online
- Paste your TopoJSON: Enter your TopoJSON topology object into the editor.
- Click Convert to GeoJSON: The tool expands shared arcs and reconstructs each geometry object as a standard GeoJSON Feature.
- Get standard GeoJSON: Copy the output for use in any mapping library — no TopoJSON parser needed.
Frequently Asked Questions
Does this tool preserve properties?
Yes. Any properties attached to geometries in the TopoJSON objects collection are preserved in the resulting GeoJSON Feature objects.
Is this tool safe?
Yes. All processing happens 100% client-side in your browser. Nothing is uploaded to any server.
Is this tool free?
Yes, completely free with no usage limits or registration required.
Real-World Examples
A data journalist using D3.js to create a choropleth map often starts with TopoJSON from a government data portal. After generating the visualization, they convert the TopoJSON back to GeoJSON using this tool so the raw data can be shared with readers as a standard downloadable format.
Related Tools
- WKT to GeoJSON — Convert Well-Known Text geometry strings to GeoJSON.
- GeoJSON to KML — Convert GeoJSON to Google Earth KML format.
- GeoJSON Viewer — Visualize GeoJSON data on an interactive map.