Working with GeoJSON: Mapping and Geospatial Data in JSON

GeoJSON is a standard format for encoding geographic data structures using JSON. It's used by mapping libraries, GIS tools, and location-based services.

GeoJSON Structure

Every GeoJSON object has a type property:

{
  "type": "Feature",
  "geometry": {
    "type": "Point",
    "coordinates": [-73.9857, 40.7484]
  },
  "properties": {
    "name": "Empire State Building",
    "city": "New York"
  }
}

Geometry Types

GeoJSON supports seven geometry types:

Point — Single location:

{ "type": "Point", "coordinates": [102.0, 0.5] }

LineString — Path between points:

{ "type": "LineString", "coordinates": [[102.0, 0.0], [103.0, 1.0]] }

Polygon — Area with boundary:

{
  "type": "Polygon",
  "coordinates": [[[100.0, 0.0], [101.0, 0.0], [101.0, 1.0], [100.0, 1.0], [100.0, 0.0]]]
}

Other types: MultiPoint, MultiLineString, MultiPolygon, GeometryCollection.

Feature Collection

Group multiple features:

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "geometry": { "type": "Point", "coordinates": [-73.9857, 40.7484] },
      "properties": { "name": "Empire State Building" }
    },
    {
      "type": "Feature",
      "geometry": { "type": "Point", "coordinates": [-73.9851, 40.7589] },
      "properties": { "name": "Rockefeller Center" }
    }
  ]
}

Coordinate Order

GeoJSON uses [longitude, latitude] (x, y) order, not [lat, lng]. This is a common source of errors.

Popular Libraries

Mapbox GL JS — Interactive maps with GeoJSON

Leaflet — Lightweight map library

Turf.js — Geospatial analysis in JavaScript

GeoPandas — Python geospatial data analysis

Tips

Use "crs" property if not using default WGS84

Keep coordinate precision to 6 decimal places (~0.1m accuracy)

Validate GeoJSON with tools before using in production

Use FeatureCollections for multiple geometries

Validate your GeoJSON with our JSON Validator and explore structure with JSON Viewer.