Ducks Unlimited vs ViaCep

Ducks Unlimited publishes a public ArcGIS Feature Service listing its university and collegiate conservation chapters as geocoded point locations across the US and Canada. It's read-only and needs no API key — queryable with the standard Esri REST query syntax (WHERE clauses, field selection, spatial filters) and exportable as JSON, GeoJSON, CSV, KML, and several other GIS formats. The dataset is licensed under Creative Commons Attribution-NonCommercial 4.0, so results can be reused non-commercially with attribution.

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.