GeoJSON

GeoJSON, standardized as RFC 7946, is a JSON-based format for encoding geographic data structures — points, lines, polygons, and collections of them — alongside their non-spatial attributes. Because it is plain JSON, it drops straight into the request and response bodies of web APIs without any special serialization, which is why location, mapping, and routing APIs reach for it by default.

• Geometry primitives - Point, LineString, Polygon, and their Multi* variants cover the shapes most spatial data needs to describe.
• Features and collections - A Feature pairs a geometry with a properties object, and a FeatureCollection bundles many features into one payload.
• A fixed coordinate reference system - RFC 7946 mandates WGS 84 longitude/latitude order, removing the ambiguity that plagued earlier geospatial formats.
• JSON all the way down - It parses with the same tooling as every other OpenAPI-described API, so no separate geospatial stack is required.

In real API operations, GeoJSON is the lingua franca between mapping front-ends and the services behind them — a store-locator endpoint, a delivery-routing API, or a boundary-lookup service returns GeoJSON and a browser map renders it directly. Describing those payloads in OpenAPI keeps the geometry contract explicit and machine-checkable, and as agents begin consuming spatial APIs, a predictable RFC 7946 shape means an agent can reason about “where” without bespoke parsing for every provider.