I have a very large shape/geojson file with around 150 polygons. Some polygons has as many as 2700 points! This is overkill for my purpose of rendering outlines on a mobile device and I would simply like to downsample to a less fine resolution.

Is this possible and if so, what software to use? I have tried doing it manually (by dropping decimal places and eliminating duplicates) but I am not sure if I trust the result.

  • 1
    The method is called as "simplification" or "generalization". Make a web search, do some reading and if necessary come back with a less broad question.
    – user30184
    Commented Feb 21, 2017 at 14:00
  • I would like fewer points in my shape/geojson polygon and am not sure how to accomplish this - how is that too broad a question? "Make a web search" is hardly an answer, see ConstanceL's response for what constitutes an actual useful answer. Commented Feb 21, 2017 at 14:35
  • 2
    There are dozens of libraries and tools which can simplify. You did not tell for example that a web tool would be OK foe you.
    – user30184
    Commented Feb 21, 2017 at 14:48

1 Answer 1


The online tool http://mapshaper.org/ is a very good and simple way to simplify a shapefile. Just drag and drop your shapefile (with the .dbf if you don't want to lose the attribute table) in the window, simplify with the slider and export in the wanted format.


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