API Découpage Administratif (API Geo) vs ViaCep

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.

ViaCEP is a free, high-availability web service for looking up Brazilian postal codes (CEP): given an 8-digit CEP it returns street, neighborhood, city, state, and IBGE/DDD codes, with a reverse address-to-CEP search available too. It's run by WBX and widely embedded across Brazilian dev tooling — its own docs warn that heavy bulk-validation traffic against it can trigger an automatic, indefinite IP block.