Convert GeoJSON files to TopoJSON format instantly — free, private, and entirely in your browser. Ideal for D3.js choropleth maps and compact geographic data.
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TopoJSON is a compact geographic data format created by Mike Bostock (creator of D3.js). It encodes topology by storing shared borders as arcs only once, making files typically 80% smaller than their GeoJSON equivalent. It is the preferred format for D3.js choropleth and thematic maps.
TopoJSON files are much smaller than GeoJSON, which is important for web performance. If you are building D3.js maps or any visualization that uses the topojson-client library, converting to TopoJSON is a common optimization step.
In TopoJSON, geometries are grouped under named objects inside the objects key. The default name is features. You can change it to match the data's purpose, such as states, countries, or roads.
All GeoJSON geometry types are supported: Point, MultiPoint, LineString, MultiLineString, Polygon, MultiPolygon, and GeometryCollection. Feature properties are preserved in the output topology.
Completely. All conversion happens in your browser — your GeoJSON file is never uploaded to any server. This is ideal for sensitive or proprietary geographic data.
GeoDataTools supports files up to 30MB. For larger files, consider splitting your data or using the full GeoDataTools app which uses Web Workers for optimal performance.
Need more powerful geospatial tools? Try the full app with interactive maps, filtering, and more.
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