Convert TopoJSON to GeoJSON locally - expand the topology for Leaflet, QGIS and tools. No upload.
Running locally on your device ...
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Your files never left your device
No. Everything runs in your browser - your file never leaves your device. How this is verifiable
TopoJSON is compact because it stores shared boundaries once as arcs, but most tools - Leaflet, Mapbox, QGIS, and almost every GeoJSON library - expect plain GeoJSON. This tool reads your TopoJSON, expands the arcs back into full geometries and writes a standard GeoJSON FeatureCollection you can use anywhere.
Every object in the topology is rebuilt: the arc references are resolved into complete rings and lines, and the quantized coordinates are turned back into normal longitude/latitude positions. If the topology holds several named objects, their features are merged into one FeatureCollection in order.
Everything runs entirely locally in the browser - your possibly sensitive location data never leaves your device. Honestly framed: the coordinates come back at the precision the TopoJSON stored (its quantization grid), not necessarily the original full precision. An invalid or empty TopoJSON is rejected with a clear message.
| Input formats | TOPOJSON, JSON |
|---|---|
| Output format | GEOJSON |
| Batch processing | No |
| Processing | Locally in your browser (JavaScript) |
| File upload | None |
Limitations: Converts TopoJSON to a GeoJSON FeatureCollection: the shared arcs are expanded back into full geometries for every object in the topology. Coordinates WGS84. Properties are preserved. An invalid or empty TopoJSON is rejected with a clear error.
It resolves the shared arc references back into complete rings and lines, rebuilding full standalone geometries for every object.
Yes, the feature properties stored in the topology are carried over.
Their features are merged into one GeoJSON FeatureCollection, in order.
No, the conversion happens entirely locally in the browser; location data never leaves your device.