Processed locally — your file never leaves your device
GeoJSON Buffer
Grow or shrink GeoJSON features by a fixed distance — turn points and lines into polygons, entirely in your browser.
Drop a GeoJSON, TopoJSON, KML, KMZ, GPX, zipped Shapefile or CSV file hereor click to choose a file from your deviceNothing is uploaded — the file is detected and processed entirely on your device.
How it works
- Select or drop a .geojson, .kml or .gpx file.
- Enter a buffer distance and choose its units — a negative distance shrinks polygons instead.
- Click Buffer to compute the result locally and preview it on the map.
- Download the buffered GeoJSON.
Frequently asked questions
- Is my file uploaded anywhere?
- No. The buffer is computed on your device with Turf.js — nothing is ever sent to a server.
- Can I use a negative distance?
- Yes. A negative distance erodes polygons inward. Features narrower than twice that distance disappear entirely, and the tool reports how many were dropped rather than silently losing them.
- What happens to points and lines?
- They become polygons — a buffered point is a circle, a buffered line is a corridor. A negative distance has no meaningful effect on them.
- Which units are supported?
- Meters, kilometers, feet and miles. Distances are measured geodesically, assuming WGS 84 longitude/latitude input.