API Découpage Administratif (API Geo) vs OpenStreetMap

Etalab's Découpage Administratif API looks up and cross-references France's administrative hierarchy — communes, EPCIs, départements, and régions — by name, postcode, SIREN, or geographic coordinates, with no API key required. The stored api.gouv.fr/api/geoapi.html link had gone stale, 301-redirecting to a generic data.gouv.fr listing page instead of the live docs; the real service and interactive documentation are hosted at geo.api.gouv.fr. A live Origin-header probe against the real /communes endpoint confirms open CORS, reflecting back whatever Origin is sent.

The core OpenStreetMap API serves and edits the raw map database underlying OSM — nodes, ways, and relations — over HTTPS at api.openstreetmap.org. Reading map data requires no authentication at all, while creating or modifying data requires an OAuth 2.0 token tied to an OSM account (the older Basic Auth/OAuth 1.0a login methods were retired in June 2024). It's a general-purpose data API rather than a geocoding service specifically — OSM points address-lookup users to the separate Nominatim service, and bulk-read users to Overpass.