Check and preview polygon GeoJSON

Paste a GeoJSON FeatureCollection, Feature, or Geometry that includes at least one Polygon or MultiPolygon.

• A bare Feature or Geometry is wrapped in a FeatureCollection
• Mixed collections can be previewed when at least one polygon geometry is present
• The map is fitted from the collection's computed bounding box

Validation is intentionally basic: the JSON must parse, expose a GeoJSON type, include Polygon or MultiPolygon geometry, and allow a bounding-box calculation.

• It does not verify every coordinate's semantic validity
• It does not detect or repair self-intersections
• It does not confirm winding order, projection, licensing, or boundary authority

The download wraps accepted input as a FeatureCollection when necessary but preserves the geometry rather than simplifying, closing rings, snapping vertices, or fixing topology.

• A success message is not a specialist GIS validation result
• Compare the preview with the authoritative source
• Use longitude then latitude in WGS84 for normal web-map display

If the preview is missing or appears in the wrong place, inspect the source before assuming the renderer is broken.

• Confirm the top-level JSON and geometry type names are spelled correctly
• Check for latitude-longitude reversal
• Make sure the polygon has coordinates from which a finite bounding box can be calculated
• Use a topology-aware GIS tool when the boundary must be operationally exact

This tool inspects existing polygon data. Use Draw on a Map for a temporary one-polygon draft, or the MapsMaker editor for saved shapes, styling, additional records, and publishing.

• The pasted data and result are not saved as a project
• Download before refreshing if you need to keep the FeatureCollection
• The editor separately supports GeoJSON, KML, and GPX imports within safety limits