Convert GML to TopoJSON online for free — right in your browser. No upload, no sign-up, batch conversion, coordinate systems and attributes preserved.
Efficiently convert from GML to TOPOJSON format
All processing is done locally in your browser
Output standard TOPOJSON format
Convert gml to topojson online for free — right in your browser. No upload, no sign-up, batch conversion, coordinate systems and attributes preserved.
GML (Geography Markup Language) is an XML-based geospatial data encoding standard defined by the Open Geospatial Consortium (OGC). GML provides rich geospatial data modeling capabilities, supporting complex geometry types, topology, coordinate reference systems, and spatiotemporal data. GML is widely used in European and government sectors, often for national spatial data infrastructures (SDI).
TopoJSON is a GeoJSON extension developed by Mike Bostock that encodes topology to eliminate redundant shared boundaries. Unlike GeoJSON where each polygon independently stores all vertices, TopoJSON uses arcs to share common boundaries between adjacent features, reducing file sizes by over 80%. TopoJSON is particularly suited for rendering large numbers of adjacent areas such as administrative district maps.
Converting GML to TopoJSON is one of the most common workflows in GIS. GML data usually comes from desktop GIS software, government open-data portals, or data exchange with partners, while TopoJSON is what modern tools, web maps, and platforms expect. This converter bridges the two: it reads your GML files, keeps geometry and attributes intact, and writes clean TopoJSON output — entirely in your browser, so your data never leaves your device.
No. The conversion runs entirely in your browser using WebAssembly — your files never leave your device.
Yes, completely free with no sign-up and no usage limits.
By default the output keeps the source coordinate system. If your GML file uses a projected CRS (like UTM), you can search any EPSG coordinate system by keyword or code and reproject in one step. Note: output formats that require WGS84 by specification (KML, KMZ, GPX) always reproject to WGS84 automatically.
Yes — drop several GML files at once and each one produces its own TopoJSON output.
Upload your GML file — drag and drop it onto the page, or browse from your device. You can add several files at once for batch conversion.
The conversion runs automatically in your browser. No upload, no server — your data stays on your device the entire time.
Download the TopoJSON file. Each input produces its own output, ready to use in your GIS, web map, or archive.