The Facebook Marketplace Partnership Program will enable eligible third-party partners to distribute listings on Facebook Marketplace. Third-party partner inventory will appear side-by-side with other third-party inventory and Facebook user listings in Marketplace Search and Feed. This will encourage Facebook users to discover new content and products on the partner’s website and purchase any products on that partner’s website.
Product Item API - How to upload, update, or delete products on Facebook Marketplace
Seller API - How to upload, update, or delete sellers on Facebook Marketplace