Best Buy vs eBay

Best Buy's public REST API exposes product, store, category, and recommendation data behind a free API key registered through its developer portal. Responses can be returned as either JSON or XML for most endpoints, though the newer Recommendations endpoints are JSON-only. Live probing shows the gateway actively validates keys server-side but returns no CORS headers, so it is built for server-side integration rather than direct browser calls.

eBay's REST platform — Browse, Sell, and related APIs — requires an OAuth2 client-credentials or authorization-code token, confirmed live by a standard invalid_client error from its token endpoint, and is built for server-side integration rather than in-browser calls. New developer accounts get a free daily call allowance with no published paid tier, and higher volume comes from an approval process rather than a fee.