Ducks Unlimited vs PostalCodes

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.

Postalcodes.info is a free postal-code reference for 123 countries and more than 1.8 million records. No key is needed. The JSON endpoint /api/v1/postal-code/{country}/{code} returns the place name, region and coordinates for one code. Per-country exports come as CSV, JSON or XLSX. The JSON API sends Access-Control-Allow-Origin: *, so a browser can call it directly. The /search autocomplete endpoint does not send that header.