Convert TopoJSON files to GeoJSON format instantly — free, private, and entirely in your browser. Supports all TopoJSON geometry types and transform matrices.
Drag & drop your .topojson or .json file here
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TopoJSON is a compact geographic data format created by Mike Bostock (creator of D3.js). Unlike GeoJSON, it encodes shared borders only once using "arcs", which makes files typically 80% smaller. It is widely used in D3.js choropleth maps and data visualization projects.
GeoJSON has near-universal tool support — QGIS, Mapbox, Leaflet, PostGIS, and virtually every GIS tool can read it. Converting TopoJSON to GeoJSON lets you use your data in any of these tools without the topojson-client library.
A single TopoJSON file can contain multiple named geometry collections called "objects". For example, a US atlas file might have "states" and "counties" as separate objects. When multiple objects are detected, you can choose which one to convert.
Yes. This converter fully handles TopoJSON's delta-encoded arc coordinates and applies the transform matrix (scale + translate) to produce correct geographic coordinates in the output GeoJSON.
Completely. All conversion happens in your browser — your TopoJSON file is never uploaded to any server.
TopoJSON files typically use the .topojson or .json extension. Both are accepted by this converter. The key identifier is the "type": "Topology" field in the file.
Want to visualize your converted GeoJSON on an interactive map? Try the full GeoDataTools app.
Open GeoDataTools App