Supply-Side Platform (SSP)
A supply-side platform (SSP) is the technology publishers use to sell their ad inventory programmatically "” packaging impressions, connecting to exchanges and DSPs, running auctions, and maximizing yield.
Key takeaways
- An SSP represents the sell side "” it works for publishers to monetize inventory.
- It connects publisher supply to multiple exchanges and DSPs and runs yield optimization.
- It is the mirror image of a DSP, which represents buyers.
- SSPs set floor prices, enforce ads.txt authorization, and manage private deals.
What an SSP does
An SSP aggregates a publisher's impressions, describes each one in an OpenRTB bid request, and exposes it to demand "” directly to DSPs and through ad exchanges. It manages yield through floor prices, demand mixing, and auction dynamics, and enforces authorization via ads.txt and sellers.json so buyers can trust the supply.
SSP vs DSP vs exchange
The three are often confused. A DSP buys on behalf of advertisers; an SSP sells on behalf of publishers; an ad exchange is the marketplace where their bids meet. In practice many companies operate several of these functions, which is one reason supply-path optimization exists.
Yield management
Beyond simply connecting demand, an SSP's value is optimization: dynamic floors, deal prioritization, traffic shaping, and increasingly first-party audience curation. In CTV, SSPs also handle ad-pod construction and competitive separation, which have no equivalent in display.
| Works for | Publishers (sell side) |
|---|---|
| Core job | Maximize yield on inventory |
| Connects to | Ad exchanges and DSPs |
| Buy-side mirror | Demand-side platform (DSP) |
Frequently asked questions
What is the difference between an SSP and a DSP?
An SSP works for publishers to sell inventory at the best price; a DSP works for advertisers to buy inventory efficiently. They sit on opposite sides of the same auction.
Is an SSP the same as an ad exchange?
No. An SSP represents publisher supply and often connects into exchanges; the exchange is the neutral marketplace that matches buy and sell bids. Many platforms blur the line by doing both.
What does an SSP do in CTV?
In connected TV, the SSP also assembles ad pods, enforces competitive separation, and manages frequency across a stream "” responsibilities that don't exist in standard display.