About TopoJSON
An extension of GeoJSON that encodes topology!
TopoJSON
https://github.com/topojson/topojson
The TopoJSON Format Specification
https://github.com/topojson/topojson-specification
TopoJSON Client
https://github.com/topojson/topojson-client
TopoJSON Simplify
https://github.com/topojson/topojson-simplify