A supply-side platform is an advertising technology platform used by publishers to manage, sell and optimize their ad space (or inventory), via websites and mobile applications. These ads can be video or display ads.

Supply-side platforms connect directly to ad networks, data-management platforms, demand-side platforms and ad exchanges to sell ad inventory for websites and app owners.

Supply-side platforms are beneficial for publishers who may be managing complex and volatile programmatic ad purchases with different ad networks at one time. These platforms help ensure the various requirements and limitations for those ad networks are met.

Supply-side platforms may use advanced algorithms to predict which network provides the most effective results during a certain period.