Shapefile Reducer — free & private
Reduce large Shapefiles in the browser: simplify geometry, clean coords, filter polygons, and split into batches. No uploads.
FAQ
Is my Shapefile uploaded to a server?
No. Parsing and reduction run locally in your browser (in a web worker). Your data stays on your device.
What should the Shapefile .zip contain?
At minimum: .shp + .dbf, and ideally .shx too. A .prj is recommended. Files should share the same base name and be included in the ZIP.
How big a Shapefile can I reduce in the browser?
There is a hard limit at 500 MB to avoid crashing the tab. Files above about 50 MB may take noticeably longer and the preview is simplified to keep things responsive.
What does “Clean coordinates” do?
It runs a cleanup pass to remove common geometry issues like duplicate points and small coordinate glitches. It is meant to make exports more reliable, not to fully repair every invalid polygon.
Will simplifying break my polygons?
It can if tolerance is too aggressive. Start small, check the preview, then increase gradually. High quality mode is slower but usually preserves shape better at the same tolerance.
How should I pick simplify tolerance?
Tolerance is in the same units as your data. If your Shapefile is WGS84 (degrees), values like 0.00001 to 0.0001 are common. If your Shapefile is in meters, tolerance is also meters, so you will typically use larger numbers.
What does “Keep only Polygon / MultiPolygon” do?
It filters out points and lines and keeps only polygons. This is useful for AOIs and boundaries. If your dataset is points or lines, turn it off.
How does batching work and why might my browser ask for permission?
Batching splits the output into multiple smaller Shapefile ZIPs (N features per batch). When “Download each batch individually” is enabled, the tool triggers multiple downloads, and some browsers will ask you to allow that.
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