Which RFC 7946 rules are checked?

Valid top-level type, required members per type, longitude in [-180,180] and latitude in [-90,90], at least two numbers per position, lines with 2+ positions, polygon rings with 4+ positions that are closed (first equals last), and right-hand-rule winding.

Is winding order treated as an error?

RFC 7946 says exterior rings should be counter-clockwise and holes clockwise, but parsers must accept either. So winding issues are reported as warnings, not hard errors.

Does it validate the properties of a feature?

It confirms that properties is present and is an object or null, as the spec requires, but it does not impose any schema on the property values themselves.

Is my GeoJSON uploaded?

No. Parsing and every check run locally in your browser with JavaScript, so your geographic data never leaves your machine.

What if the JSON itself is malformed?

If the text is not valid JSON, the tool reports the JSON parse error first, because structural validation can only run once the document parses.

GeoJSON Validator — Gera Tools

Validate GeoJSON against RFC 7946 in your browser

This tool checks a GeoJSON document against the structural rules of RFC 7946, the specification that defines GeoJSON. It catches the mistakes that silently break maps — out-of-range coordinates, unclosed polygon rings, too-few points — and tells you exactly which feature is at fault. It is built for developers wiring up Leaflet, Mapbox or a spatial database.

How it works

The tool first parses the text as JSON. It then walks the document by type:

FeatureCollection must have a features array; each entry is validated as a Feature.
Feature must carry a geometry and a properties member (object or null).
Geometry is checked per type — every position needs at least two numbers with longitude in [-180, 180] and latitude in [-90, 90]; LineString needs 2+ positions; each Polygon ring needs 4+ positions and must be closed (first position equals last).

Polygon winding order (exterior counter-clockwise, holes clockwise per the right-hand rule) is reported as a warning, since RFC 7946 requires parsers to accept either order.

Notes

Everything is computed locally — nothing is uploaded. Errors name the feature index and the rule that failed so you can jump straight to the problem.