About

This tool acts as a bridge between the proprietary ESRI ArcGIS ecosystem and the open-source GeoJSON standard. ArcGIS data, often served via REST endpoints, uses a specific JSON structure (featuring rings, paths, and spatialReference) that is incompatible with libraries like Leaflet, Mapbox, or D3.js.

The converter parses the ESRI geometry, transforms the coordinate structure, and optionally reprojects coordinates from Web Mercator (EPSG:3857) to WGS84 (EPSG:4326), making the data web-ready. It strictly follows RFC 7946 standards for GeoJSON formatting.

Formulas

When converting from Web Mercator (EPSG:3857) to WGS84, we apply the inverse Mercator projection. The mapping of a coordinate xy to longitude λ and latitude φ is calculated as:

λ = x × 18020037508.34

φ = 360π × atane^{y × π / 20037508.34} − 90

Here, the constant 20037508.34 represents the semi-major axis of the Earth multiplied by π.

Reference Data

Feature	ArcGIS JSON (ESRI)	GeoJSON (RFC 7946)
Point	{ x, y }	[lon, lat]
Line	paths: [[...]]	LineString or MultiLineString
Polygon	rings: [[...]]	Polygon (Outer CCW, Inner CW)
Attributes	attributes: { ... }	properties: { ... }
CRS	spatialReference: { wkid: 3857 }	Assumes WGS84 (EPSG:4326)

Frequently Asked Questions

Yes, but strictly for Web Mercator (EPSG:3857) to WGS84 (EPSG:4326). If your data is in a local projection (e.g., NZGD2000 or State Plane), the geometry structure will be converted to GeoJSON, but the coordinates will remain unchanged unless they match the Mercator signature.

GeoJSON (RFC 7946) requires the "Right-Hand Rule": exterior rings must be Counter-Clockwise, and holes Clockwise. ArcGIS often stores rings in random orders. This tool attempts to correct simple winding issues, but complex topology errors in the source may persist.

Yes. The tool accepts full FeatureCollections, individual Features, or just the geometry objects. It automatically wraps single features into a standard FeatureCollection for compatibility.

No. All parsing, conversion, and rendering happen 100% inside your browser using JavaScript. No data leaves your device.