adresse.data.gouv.fr vs API Découpage Administratif (API Geo)

The Base Adresse Nationale's API Adresse geocodes and reverse-geocodes French addresses for free with no API key, backed by Etalab and IGN's data.geopf.fr infrastructure (the older api-adresse.data.gouv.fr host still answers directly and does not redirect). Requests and responses use the GeoJSON FeatureCollection format, with each result scored for match confidence and enriched with INSEE city codes, postcodes, and population. A live Origin-header probe confirms open CORS (Access-Control-Allow-Origin: *), so it works directly from browser JavaScript with no proxy.

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.