How to simplify GeoJSON files

When downloading GeoJSON files to create your own map in Flourish, they can have very large file sizes. This is usually because of the details within shape regions taking a lot of space. To make your map display well and load quickly, we recommend using GeoJSONs up to 5 MB in size.

To simplify GeoJSON files, we recommend using the free tool Mapshaper and following these steps.

    1
    Open mapshaper.org and import your GeoJSON files by using the upload link or dragging your files into the webpage.

    2
    Once the file has loaded into Mapshaper, click the "Simplify" link in the top right corner of the webpage.

    3
    A box will then appear, offering different ways to simplify your GeoJSON. Hover over the question mark next to the option to find out more information about what each option offers. "Prevent shape removal" is useful for small areas not disappearing when editing at a high simplification. Click apply after you have chosen the options you want.

    4
    A slider will then appear on the top of the webpage. Here, you can choose how much you would like to simplify your map. As you slide the slider, you can see the map becoming less detailed. This is an indication of how the final map will look. You can click the simplify option again to remove the slider and keep the simplification.

    5
    If you see a warning about Line Intersections in the top-left corner, simply click Repair. This will ensure that gaps are closed and can be useful when using our region grouping / highlighting feature. You are now ready to export your map! Click the export option and choose to export the file as a GeoJSON.

Your new GeoJSON file is ready to be imported into Flourish.