Union GeoJSON
Combine overlapping GeoJSON polygons into one Polygon or MultiPolygon while preserving a predictable output structure.
Input
Properties from multiple source features cannot be merged automatically and are summarized in output metadata.
Review these warnings
GeoJSON
Map preview
Understanding Union GeoJSON
Spatial relationships and derived geometry
Combine overlapping GeoJSON polygons into one Polygon or MultiPolygon while preserving a predictable output structure.
Union GeoJSON evaluates where features lie relative to one another or creates geometry from that relationship. Geometry validity, boundary rules and compatible coordinate assumptions control the result.
How to verify the operation
Properties from multiple source features cannot be merged automatically and are summarized in output metadata.
Review Union GeoJSON with feature counts, empty outputs, boundary cases and a few known examples. Confirm units and CRS assumptions before treating the result as authoritative.