GeoJSON validator

Validate bounded GeoJSON geometry structure and WGS84 coordinate positions locally.

How it works & useful details

How it works & limits

Checks the core GeoJSON geometry types, finite WGS84 longitude/latitude positions and polygon ring closure. Parsing is local and inert; no linked data, URLs, maps or extensions are loaded.

Limit: 500,000 characters, 1,000 features, 20,000 positions and 24 nested geometry levels. It is a structural checker, not full schema certification.

Private local calculation

Coordinates and pasted data stay in this browser tab. These tools use no map tiles, geocoding, routing, elevation data or network requests.

About this tool

GeoJSON validator checks whether a GeoJSON document has valid geometry structure and whether its coordinates fall inside WGS84 latitude and longitude ranges. It catches the issues that make a map client silently fail.

Validation is bounded and local. The validator does not fetch referenced files or schemas, and it reports what it checked so you know which guarantees apply.

How to use it

Paste the GeoJSON document.
Validate to see structure and coordinate-position results.
Fix the reported geometry or coordinate problems.
Re-run validation until the document passes.

Worked example

This minimal FeatureCollection is valid:

{
  "type": "FeatureCollection",
  "features": [{
    "type": "Feature",
    "properties": { "name": "Sample point" },
    "geometry": { "type": "Point", "coordinates": [-0.1278, 51.5074] }
  }]
}

The validator reports the root type, one feature, one geometry, and one coordinate position. If the coordinates were swapped to [51.5074, -0.1278], the document would still be valid, but the point would move from London to the Indian Ocean. A validator can confirm structure, not intent, so check a sample on a map.

The most common GeoJSON errors

Latitude first: GeoJSON (RFC 7946) orders positions as [longitude, latitude], the opposite of how coordinates are usually spoken.
Unclosed polygons: a polygon ring's first and last positions must be identical, and a ring needs at least four positions.
Wrong nesting depth: a Polygon's coordinates are an array of rings, each an array of positions. It is easy to lose or add a bracket level.
Out-of-range values: longitude must be within −180 to 180 and latitude within −90 to 90. Projected coordinates such as metres in a national grid are not valid GeoJSON.
Missing geometry wrapper: a Feature needs "type": "Feature", a geometry object or null, and a properties member.

Frequently asked questions

Does it validate against a JSON Schema?

It performs structural checks on geometry types and coordinate arrays rather than full schema validation.

What coordinate order does GeoJSON use?

Longitude first, then latitude, as defined by the GeoJSON specification. Reversed pairs are a common cause of strange map output.

What is the limit?

Up to 500,000 characters of GeoJSON text.

Does it check ring winding order?

It checks structure, finite positions, ranges, and ring closure. RFC 7946 recommends counter-clockwise outer rings, but most software accepts either order, so winding is not enforced.