What an SSP is
An SSP is a supply-side platform. It is the software a screen operator or media owner uses to sell their digital out-of-home inventory programmatically. Think of the company that owns the physical screens, the panels in a transit hub, the boards along a highway, the displays in a mall. Their screens are the supply, and the SSP is how they put that supply up for sale.
The supply-side platform does the work of packaging screens into buyable inventory: it groups them, attaches audience and location data, sets the rules for what can run, and sets a floor price below which a screen will not sell. Then it exposes that inventory to buyers, either through an open exchange where demand bids for it, or through direct and reserved deals arranged in advance. When a buyer wins a slot, the SSP is what tells the physical screen to play that ad.
In digital out-of-home the SSP represents the sell side, the operator's interest. Vistar Media, Place Exchange and Broadsign all operate here, connecting the screens they represent to programmatic demand. Blindspot is not an SSP. It never lists or sells screens; it buys across the supply that platforms like these make available.
What a DSP is
A DSP is a demand-side platform, and it sits on the opposite side of the same market. It is the software advertisers and agencies use to buy inventory. Where the SSP represents the operator selling screens, the DSP represents the brand that wants its ad on those screens. The demand side is the buy side.
A demand-side platform connects to supply, lets a buyer target the screens they want by location, audience and context, and then bids for those screens, usually priced per thousand impressions, or CPM. It runs the campaign, decides how much to pay for each opportunity, and reports on delivery. Basis and The Trade Desk are demand-side platforms that operate a trading seat: a licensed account, often set up and run by a trading desk or an agency team, that connects to the wider programmatic market.
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screens Blindspot buys across, buy-side
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countries of supply reached
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advertisers buying on Blindspot
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hours to go live, per play
A self-serve buying platform like Blindspot also sits on the buy side, the same side as a DSP. The difference is how you buy. There is no trading seat to license and no trading desk to run it for you. You plan and book directly, per play, on a map, so the buy side is open to a first-time advertiser as much as to an agency seat.
How they connect, and where Blindspot fits
The two sides meet in the middle. An operator lists screens through its SSP; a buyer expresses demand through a DSP or a self-serve platform; an exchange matches the two, clears a price, and the winning ad plays on the screen. It is the same buy-and-sell shape as the rest of programmatic advertising, applied to physical screens on real streets. The whole flow is what people mean by programmatic DOOH, covered in full in the programmatic DOOH guide.
Blindspot sits on the buy side, but as a self-serve platform rather than a seat. You open a map, pick screens across more than 3 million of them in 50-plus countries, set an hourly schedule, and book, with the per-play price and live availability shown on every screen before you commit. Because there is no seat and no minimum spend, a budget of any size buys the real exposure it needs rather than filler plays, so it works as hard on a first campaign as on a worldwide flight. If you would rather not build the plan by hand, Blinky, the free AI planner, will read a one-line brief and propose one across that supply, which you then adjust and publish.
So the honest answer to "is Blindspot an SSP or a DSP" is neither exactly: it is the buy-side, self-serve way to buy across the supply that SSPs represent, without operating a demand-side seat. If you buy programmatically at an agency, compare the field in the DOOH platform for agencies guide, or just start booking.
SSP sells the screens. DSP buys them. Blindspot buys them without a seat.
SSP vs DSP, in one line