Flipkart Marketplace vs OLX Poland

Flipkart's Marketplace Seller API issues OAuth2 bearer tokens through either a client-credentials or an authorization-code grant, for self-access and third-party seller applications respectively. Its own documentation explicitly requires HTTPS and states plain HTTP requests are rejected, with tokens typically valid for around 60 days before they must be renewed.

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.