eBay vs OLX Poland

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.

OLX Poland's Partner API lets approved integrators create and manage classified-ad listings and handle buyer/seller messaging programmatically. Access runs on an OAuth2 client-credentials flow, confirmed live by an invalid_client error from the real token endpoint, and the older v1 REST resource has been explicitly deprecated in favor of this OAuth-secured surface. Developer access comes through an application and approval process rather than a published self-serve fee.