TopoJSON to GeoJSON Converter
Expands a compact D3-style topology into the standard FeatureCollection almost every other tool expects.
Convert TopoJSON to GeoJSON now
Common issues converting TopoJSON to GeoJSON
- By default every 'object' in the TopoJSON becomes its own FeatureCollection feature. If you only want one (e.g. 'counties'), strip the others from the input first.
- Quantization is reversed during expansion, so absolute coordinates are restored — but the precision is whatever the original quantization allowed.
- File size grows 5-10x after expansion. If you're shipping to a browser, consider keeping the TopoJSON and expanding at runtime with topojson-client.
- Properties on each topology object ride along to the resulting features unchanged.
Frequently asked questions
Why is the output so much bigger?
TopoJSON deduplicates shared boundaries; GeoJSON doesn't. Expanding typically grows file size 5-10x, occasionally more on dense polygon networks.
Are all objects in the topology expanded?
Yes — every top-level object in the 'objects' field becomes a feature in the output. Strip unneeded objects from the input first if you only want a subset.
Is precision preserved?
The topology restores absolute coordinates from its delta-encoded arcs, but precision is bounded by the original quantization. For country-level maps this is usually indistinguishable from the source.
What libraries render GeoJSON directly?
Essentially all of them: Leaflet, Mapbox GL, OpenLayers, deck.gl, QGIS, ArcGIS, and D3-geo. GeoJSON is the universal default.