What is a .TopoJSON file?
TopoJSON is a GeoJSON extension that stores shared borders only once, making map files smaller.
- Did you know
- TopoJSON encodes topology so neighbouring regions share their boundaries instead of repeating them.
- TopoJSON stitches shapes from shared line segments called arcs, so a border between two regions is stored only once.
- With delta-encoded integer coordinates, files are often around 80 per cent smaller than the equivalent GeoJSON.
- What Analyser reads
- Inspect geospatial and GIS files without a map: TopoJSON, OpenStreetMap XML, Esri Shapefile siblings (SHP/SHX/DBF/PRJ/CPG), world files, GML, NMEA GPS logs, IGC flight logs, MapInfo TAB/MIF, GDAL VRT, PMTiles, DTED terrain, Esri ASCII grids and SRTM .hgt - surfacing CRS/EPSG, feature/record counts, bounding boxes and elevation ranges. GRIB/NetCDF/GeoPackage/MBTiles/MrSID/ECW identified.
- Depth of analysis
- .TopoJSON is an identification-grade format: Analyser recognises it from its bytes and decodes the header metadata it carries, rather than opening it in a full viewer. Formats that do get a full viewer are marked "Full" on the formats page.
- Open a .TopoJSON file
- Drag a .TopoJSON file onto the Analyser home page (or tap to pick one). It is identified entirely in your browser - nothing is uploaded, there is no account, and it works offline once installed.