GeoJSONVT

GeoJSON-VT is a lightweight JavaScript library for converting GeoJSON data into vector tiles suitable for client-side rendering. It ingests a GeoJSON object and, using a set of options, builds a tile index that can be queried for any tile at a given zoom, x, and y coordinate. It is designed to handle very large GeoJSON datasets efficiently by streaming and indexing features across a tiled grid, rather than decoding the entire dataset for every tile.

It uses a fixed tile extent (default 4096 units) and can clip and simplify geometries to fit tile boundaries. Options include maxZoom (maximum zoom level to index), indexMaxZoom (number of zoom levels to index for faster tile retrieval), indexMaxPoints (limit on point count per feature before it is indexed), extent (tile extent), and buffer (extra surrounding area around the tile to avoid clipping).

The API provides a factory geojsonvt(geojson, options) that returns an object with a getTile(z, x, y) method. A returned tile includes a features array; each feature carries a geometry in tile coordinates, a type, and a copy of original properties. This enables rendering with vector tile-aware libraries, such as Mapbox GL JS, Leaflet with vector tiles, or other MVT consumers.

GeoJSON-VT is used to render dense or large-scale geographic datasets efficiently in browsers without pre-tiling on the server. It is open-source and widely referenced in web mapping workflows.