SupplySidePlatforms

SupplySidePlatforms (SSPs) are adtech platforms used by publishers to manage and sell digital advertising inventory programmatically. An SSP connects a publisher's ad inventory to multiple demand sources, including demand-side platforms (DSPs), ad exchanges, and ad networks, enabling automated auctions and direct deals.

Publishers implement an SSP on websites or apps. The platform aggregates available impressions with associated metadata such as format, size, audience signals, and context, applies price floors and deal terms, and submits bid requests to demand partners. On each impression, the highest eligible bid wins and the winning ad is served. SSPs typically support open auctions, private marketplaces (PMPs), and programmatic guaranteed arrangements, and many support header bidding to allow multiple demand sources to bid in parallel. The relationship to ad servers is usually complementary, with the SSP feeding inventory data to the publisher’s ad server and receiving creatives for serving.

Key features include yield optimization through floor control, deal management (including PMPs and direct deals), integrations with measurement and brand-safety services, reporting and analytics, and fraud prevention tools.

In the programmatic advertising ecosystem, SSPs give publishers more control over pricing, inventory allocation, and demand quality, while helping maximize revenue by connecting to a broad set of buyers. Compliance with privacy regulations and identity solutions continues to influence SSP design and data handling.