GeoJSON viewer

What the viewer checks

Points need a position of at least two numbers, with longitude between −180 and 180 and latitude between −90 and 90. Lines need at least two positions. Every polygon ring needs at least four positions. A file that breaks these rules stops with a message naming the problem, so you know the file, not the viewer, needs fixing.

How to use it

1. Drop your .geojson or .json file onto the box, or click to choose it.
2. Features appear on the map, which zooms to fit them. Multi-part geometries are drawn as their parts.
3. If the file is invalid, a notice names the problem, such as bad coordinates or a ring with too few points.
4. Press KML or GPX to convert, or GeoJSON for a cleaned copy.

GeoJSON in brief

GeoJSON is a JSON format for geographic features, specified in RFC 7946. A FeatureCollection holds Features, and each Feature has a geometry and a properties object. Positions are written longitude first, then latitude, in decimal degrees on WGS84.

The most common mistake in hand-made files is swapping the order to latitude, longitude. US points then land in Antarctica or off the map. If your shapes appear in the wrong hemisphere, check the order.

Multi-part and collection geometries

MultiPoint, MultiLineString, MultiPolygon, and GeometryCollection are split into simple parts so each can be drawn and exported. Each part keeps the feature's properties. Features with a null geometry are skipped, as RFC 7946 allows them.

Property values are converted to text for display and export. Nested objects do not survive that step, so flatten them first if you need them in the KML or GPX file.

Converting to KML or GPX

KML export writes one Placemark per part, ready for Google Earth. GPX export writes points as waypoints and lines as tracks for GPS units. Both are built in your browser. For a spreadsheet of points instead, the CSV to map tool reads the other direction.

Getting a GeoJSON file

Many open data portals offer GeoJSON downloads for boundaries, parks, and transit stops. QGIS exports any layer as GeoJSON. If a portal offers only shapefiles, convert them in QGIS first; the viewer does not read .shp files. Files larger than 8 MB need to be simplified or split before loading.