Layer viewer: your data on the map
Open a GeoJSON file or a table with coordinates, combine it with public layers, filter by attribute and measure distances and areas. It's processed in your browser: nothing is uploaded.
WGS 84 (EPSG:4326) · geodesic distances and areas
How it works
- Add up to 4 layers: GeoJSON (points, lines or polygons) or CSV/Excel with latitude and longitude columns. If the names aren't recognised, you choose the columns.
- Click a feature on the map or in the table to see its attributes, centroid and measurements.
- Filter by attribute: the map, the totals and the download use only the filtered features.
- With “Measure distance”, each click on the map adds a point and the great-circle distance is added up.
Reference system and calculations
- Coordinates are read as WGS 84 decimal degrees (EPSG:4326), as GeoJSON requires (RFC 7946). If the file declares another system you'll be warned; coordinates outside ±180° / ±90° are discarded.
- Distances, lengths and areas are calculated on a sphere with the Earth's mean radius (6,371.0088 km). Compared with the WGS 84 ellipsoid the difference is usually under 0.5%.
- The centroid is the spherical centre of mass of the geometry; for very concave polygons it may fall outside them.
Sources of the public layers
- Earthquakes: United States Geological Survey (USGS), ComCat catalogue, read when the layer is loaded; magnitude 4.5 or above in the last 7 days. Public domain.
- Ports and airports: Natural Earth 1:10m, public domain.
Limits
- Up to 60 MB and 50,000 features per layer. It doesn't read shapefiles, KML or raster layers: convert them to GeoJSON first (for example, with QGIS).
- It doesn't transform between projections: if your data is in metres (UTM, ETRS89 / UTM), convert it to degrees first.
- Layers only live in this tab: they disappear when you close it. Download anything you want to keep.