Programmatic and trading
DSPs, SSPs, and DOOH Exchanges
What are DSPs, SSPs, and exchanges, and how do they connect buyers to screen owners in DOOH? Roles, the data partner concept, and a clear role table.
11 min readUpdated
DSPs, SSPs, and DOOH Exchanges
DSPs, SSPs, and exchanges are the three core software layers of programmatic advertising; they connect advertisers and agencies with screen owners automatically. This article explains what a DSP (Demand-Side Platform) and an SSP (Supply-Side Platform) are, how an exchange connects the two, how these roles work in digital out-of-home (DOOH) advertising, and the concept of the data partner.
What is a DSP?
DSP stands for Demand-Side Platform. As the name suggests, it represents the demand side — the advertisers and agencies that want to buy ad space. Through a DSP, a buyer defines its campaign’s target audience, geographic area, budget, bid strategy, and which kinds of inventory it will bid on.
A DSP’s job is to translate these rules into automated bids. When an ad opportunity arises (for example, an open play slot on a screen), the DSP evaluates in under a second whether the opportunity matches the buyer’s criteria, and bids if it does. A single DSP can manage simultaneous bids across thousands of screens and multiple exchanges, so the buyer never has to negotiate with each screen individually.
What is an SSP?
SSP stands for Supply-Side Platform. It stands opposite the demand side: it represents the sell side — the screen owners and media owners. In a DOOH context, the owner of a screen network connects its inventory to an SSP and opens that inventory to programmatic buyers.
An SSP’s core tasks are to offer inventory to auction, manage incoming bids, apply floor prices, and maximize fill rate. For the screen owner, an SSP is the way to open inventory automatically to a broad pool of buyers rather than selling to buyers one at a time. An SSP also lets the screen owner enforce rules about which ads may appear (brand safety).
How does an exchange connect the two sides?
An ad exchange is the marketplace between DSPs and SSPs. It receives bid requests from SSPs, distributes them to the relevant DSPs, collects the bid responses, and determines the winner. This matching can run on real-time bidding (RTB), just as in programmatic web advertising.
In practice, the SSP and exchange functions can sometimes merge into a single platform; some providers offer both a sell-side service and exchange functionality. What matters is seeing the conceptual distinction: the DSP represents the buyer, the SSP represents the seller, and the exchange is the neutral matching layer that brings them together. We cover how the whole chain works, and which deal types it supports, in the programmatic DOOH article.
How do the roles work in DOOH?
| Role | Side it represents | Core function |
|---|---|---|
| Advertiser / agency | The brand itself | Sets the campaign goal and budget |
| DSP | Demand (buyer) | Translates targeting rules into bids |
| Exchange | Marketplace | Matches bid requests and responses |
| SSP | Supply (seller) | Offers inventory to auction, manages fill |
| Data partner | Measurement provider | Supplies audience and attention data |
| Screen owner | Media owner | Operates the physical screen network |
In DOOH, this core architecture is borrowed from web advertising but requires an important adaptation. On the web, an ad is shown to one person, whereas a single play on a DOOH screen is seen by many people. So the bid request must carry not only the “this screen, this location” information but also an estimate of how many people that play will reach. We examine in detail how this estimate is placed into the bid stream in the OpenRTB and the impression multiplier article.
The data partner concept
An increasingly decisive component of the programmatic chain is the data partner. The data partner is neither a buyer nor a seller; it supplies audience and attention data that both sides can use. A DSP needs this data when it wants to base its bid decision not only on location but on data about “which audience profile is seeing this screen right now.”
Audience data in DOOH today is mostly modeled from mobile-location and panel data — that is, “who passed that point” is estimated. Computer-vision-based measurement providers (such as Mecrai) can add to this picture anonymous people counting in front of the screen, dwell time, and head-pose attention (face turned toward the screen). This method performs face detection, not face recognition; the output is only aggregate and anonymous.
The value of the data partner lies in how the data it supplies enriches buying. A location-based bid says, “this screen is in the city center”; a bid enriched with audience data can say, “this screen is being seen right now by an audience of roughly this size, with this much attention.” This enrichment is also the foundation for measurement turning into a pricing basis — what the sector calls a currency.
Summary
A DSP represents the buyer, an SSP represents the seller, and an exchange is the marketplace that matches them. In DOOH, this architecture is borrowed from the web but adapted because a single play reaches many people. The data partner layer adds audience data into this chain, making programmatic buying not just automated but grounded in audience information.
Frequently asked questions
- What is the core difference between a DSP and an SSP?
- A DSP represents the demand side — the advertisers and agencies that buy ad space — and bids on their behalf. An SSP represents the supply side — the screen owners that sell ad space — and offers inventory to auction. One buys, the other sells.
- Are an exchange and an SSP the same thing?
- Conceptually they differ: an exchange is the neutral marketplace that matches buyers with sellers, while an SSP represents only the sell side. In practice, however, some providers combine both functions in one platform, so the terms are sometimes used interchangeably.
- What does a data partner do in DOOH?
- A data partner supplies audience and attention data that buyers and sellers can use. This data makes it possible to bid based not only on location but on the estimated audience seeing the screen, which sharpens targeting.
- Can a buyer in DOOH purchase directly from the screen owner?
- Yes, traditional direct buying is still possible. But in a programmatic architecture, the buyer reaches thousands of screens simultaneously through a DSP rather than negotiating with each screen owner individually, which provides scalability and targeting flexibility.
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