GeoJSON
GeoJSON (RFC 7946, published August 2016) is the IETF-standardized JSON format for geographic data, replacing the original 2008 spec and underpinning most modern web mapping toolchains.
What Matters
- RFC 7946 locks the CRS to WGS84; alternative CRS requires prior arrangement between parties, removing the earlier spec’s flexibility.
- Geometry types: Point, LineString, Polygon, plus Multi- variants; Features wrap geometry with properties; FeatureCollections group Features.
- TopoJSON adds arc-based topology on top of GeoJSON, significantly reducing point counts for curves; now largely supplanted by Vector Tiles/PMTiles for visualization.
- GeoPackage (SQLite-backed) is the common alternative: supports multiple layers, distinct schemas per layer, explicit CRS, and smaller file sizes.
- [HN: @Waterluvian] Used GeoJSON to map tens of thousands of warehouse robots in a flat CRS—tools that hardcode WGS84 assumptions will silently corrupt calculations.
- [HN: @Stratoscope] Shared-boundary simplification breaks in GeoJSON: adjacent polygon borders are stored independently, so simplification creates gaps and overlaps between US states.
- [HN: @jackconsidine] Getcho (logistics) uses zip-code GeoJSON polygons to draw zone maps and generate delivery rates; OpenDataDE repo has all 2010 census ZIP geometries.
