Terraformer is a geo-toolkit designed to run in both the browser and server-side via Node.js. It includes the ability to operate on multiple types of primitives: points, lines, polygons, multi polygons and collections. It allows for several types of operations against those primitives such as determining intersections, within, and convex hulls. In addition, Terraformer provides tools for conversions between GeoJSON, Esri-JSON, and Well Known Text.
One of the most interesting aspects of Terraformer is the GeoStore. The GeoStore is a spatial database toolkit that works with multiple types of spatial indexes and database backends and allows developers to create bespoke spatial databases. The GeoStore ecosystem currently includes an RTree index, a BTree index, memory stores, and a leveldb store, with more being added on a regular basis.