GeoJSON is an open standard format designed for representing simple geographical features, along with their non-spatial attributes. It is based on the JSON format.

The features include points (therefore addresses and locations), line strings (therefore streets, highways and boundaries), polygons (countries, provinces, tracts of land), and multi-part collections of these types. GeoJSON features are not limited to representing entities of the physical world only; mobile routing and navigation apps, for example, might describe their service coverage using GeoJSON.

The GeoJSON format differs from other geographic information system standards in that it was written and is maintained not by a formal standards organization, but by an Internet working group of developers.

A notable offspring of GeoJSON is TopoJSON, an extension of GeoJSON that encodes geospatial topology and that typically provides smaller file sizes.

The GeoJSON format working group and discussion were begun in March 2007 and the format specification was finalized in June 2008.

In April 2015 the Internet Engineering Task Force founded the Geographic JSON working group which released GeoJSON as RFC 7946 in August 2016.

Points are [x, y] or [x, y, z]. They may be [longitude, latitude] or [eastings, northings]. Elevation, in meters, is an optional third number. They are decimal numbers.

For example, London (51.5074° North, 0.1278° West) is [-0.1278, 51.5074]