TopoJSON to GeoJSON

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.

The price of the conversion is size: because GeoJSON stores shared borders twice - each polygon carries its full outline even when the neighbouring polygon shares it - the GeoJSON output is often noticeably larger than the compact TopoJSON. In return it loads in every common mapping tool without any extra library.

Specifications

In 3 steps

1. Drop your TopoJSON file.
2. The conversion runs automatically.
3. Download the GeoJSON (e.g. for Leaflet).

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.

FAQ

Related tools

GeoJSON to TopoJSON · KML to GeoJSON · WKT to GeoJSON · GeoJSON to NDJSON · NDJSON to GeoJSON · DXF to GeoJSON