Command line tool to extract borders of GeoJSON Polygons into a non-overlapping set of LineString's. See https://github.com/topojson/topojson-client#mesh

npm install

geojson-mesh [--explode] < input.geojson > output.geojson

If --explode is set, multiple features of geometry type LineString are created, otherwise a single feature of geometry type MultiLineString is created.