eBay vs WooCommerce

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.

WooCommerce's REST API isn't a centrally hosted service — every self-hosted WooCommerce store exposes its own instance, authenticated by a consumer key/secret pair sent as HTTP Basic Auth credentials over HTTPS, per WooCommerce's own documentation. Because CORS support depends entirely on each merchant's own server configuration rather than the protocol itself, it can't be verified as a single blanket property of "the API." The protocol ships free with the open-source plugin; the only cost is whatever the merchant already pays to host their own store.