Free · Local file processing · No account

Simplify KML Online

A GPS track or detailed boundary takes too long to open or contains more vertices than the map needs.

Loading the local file tool…

How to use this tool

1. Choose your KML and set a small tolerance, such as 10 meters.
2. Run simplification and compare coordinate counts.
3. Inspect the output in Studio before sharing; reduce tolerance if important details disappear.

Limits and checks before sharing

Uses Douglas–Peucker with a local planar approximation in meters, not a geodesic or topology-preserving algorithm.
Only LineString and LinearRing coordinate lists change. Points, attributes and style XML remain. Small rings are retained when simplification would collapse them.
Adjacent boundaries, holes and self-intersections need visual review. Dateline-crossing coordinate lists are rejected; polar and large-area geometry should use desktop GIS.

If processing fails, check the file extension and source contents. Use a smaller batch if memory runs low. The original files are never overwritten. Inspect known locations and attributes before sharing a result.

Frequently asked questions

Is simplifying the same as ZIP compression?

No. Simplification removes vertices and changes geometry. KMZ compression preserves the original KML bytes and is reversible.

Does this guarantee valid polygon topology?

No. Ring closure is retained, but shared borders, holes and self-intersections are not topology-checked. Inspect your output and use a GIS topology validator for production boundaries.

Are my files uploaded, and do I need an account?

No. This file operation runs in your browser and needs no account or payment. The page and processing libraries need an initial network load. Opening a map preview can request external map tiles; linked resources in your original KML are not fetched or embedded by this tool.

Continue with your result

Inspect outputs directly using the result button above. Choose a compatible next operation in the result panel to continue locally without downloading again. These related links open a fresh task. Share the downloaded file through your own channels; local files are not published to a hosted URL.