Short answerA DSP (demand-side platform) is software that advertisers use to buy ad impressions automatically. It connects to many sources of traffic, evaluates every impression against the advertiser's targeting and budget, and bids on the ones that fit, all in real time.
If you buy online advertising for more than one website, you will meet the term DSP sooner or later. This article explains what a demand-side platform does, how it decides which impressions to buy and what to look at when you choose one.
What does a DSP do?
A DSP sits on the buying side of programmatic advertising. Its job is to spend an advertiser's budget on the impressions that are most likely to bring results. To do that, it:
Connects to supply. A DSP receives bid requests from SSPs, ad exchanges and publishers, often millions per second.
Evaluates each impression. It compares the request with the targeting, schedule and budget of every active campaign.
Bids. If the impression fits, the DSP answers with a price; if not, it skips it.
Delivers the ad. When the bid wins, the DSP returns the creative or a tag that loads it.
Reports. Impressions, clicks, spend and conversions are collected in one dashboard.
Without a DSP an advertiser would have to negotiate with every site separately. With it, one campaign can run across thousands of placements.
How does a DSP decide what to buy?
Every bid request carries information about the impression. A DSP checks it against the campaign settings, usually in this order:
Format and placement. Is it a banner, a video slot, an interstitial or a popunder, and does the campaign have a creative for it?
Targeting. Country, platform (desktop or mobile), operating system, browser and other parameters. Our article on ad targeting options describes them in detail.
Quality filters. Fraud and bot filters, domain black and white lists, brand-safety rules.
Frequency. Has this visitor already seen the ad too many times? A frequency cap prevents that.
Price and budget. What is the bid for this segment, and is there budget left today?
Only impressions that pass all checks receive a bid. That is why a narrow targeting setup can spend slowly: most requests are filtered out before the auction.
What pricing models does a DSP use?
Programmatic auctions are almost always priced in CPM, the cost of one thousand impressions. Some DSPs also offer optimization toward clicks or conversions, but under the hood they still bid per impression and adjust the CPM bid to reach the goal.
For performance campaigns the key number is not the CPM itself but the cost per result. A cheap impression that never converts is expensive; a higher CPM in a segment that converts well can be the best deal in the account. That is why conversion tracking, for example postback (S2S), matters as much as the bid.
Self-serve or managed DSP?
Self-serve DSP
Managed service
Who sets up campaigns
You
A manager on the platform side
Speed of changes
Immediate
Depends on the manager
Best for
Teams with media-buying experience
Brands and teams new to programmatic
Control over bids and lists
Full
Shared
Many platforms offer both. In the Wizads DSP, for example, you can run campaigns yourself or let a personal manager set them up and manage them for you.
What should you look for in a DSP?
Traffic sources and GEOs. Where does the supply come from, and does it cover the countries you need?
Ad formats. Banner, video (preroll, autoplay), interstitial, popunder — check that the formats you plan to run are available.
Targeting depth. At minimum country, device, operating system and browser; ideally retargeting and placement lists.
Traffic quality. Own anti-bot and anti-fraud filtering, verified publishers and the option to block sources yourself. Our guide on ad fraud lists the warning signs.
Tracking. Postback support, reporting by placement and an API for exporting data.
Support. A real person who answers when a campaign behaves strangely.
A way to test. A free or low-budget test shows the real quality of traffic faster than any presentation.
DSP, ad network or ad exchange?
The terms overlap. An ad network traditionally aggregates inventory from many publishers and sells it to advertisers, often with its own DSP. An ad exchange is the marketplace where the auction happens. A DSP is the buying tool. A company like Wizads combines several roles: it runs a DSP for advertisers, an SSP for publishers and its own ad server. If the difference between the two sides is still unclear, read DSP vs SSP.
Frequently asked questions
Is a DSP only for big brands?
No. Self-serve DSPs and ad networks with a DSP let small advertisers start with modest budgets. What matters more is the ability to measure results and cut sources that do not work.
Can a DSP buy video ads?
Yes. Video impressions are requested through a VAST tag, and the DSP answers with a video creative. See VAST vs VPAID for the details.
How does a DSP connect to traffic?
Usually through the OpenRTB protocol. The SSP or exchange sends bid requests, and the DSP replies with bids within a strict time limit.
Wizads is an advertising network with its own DSP, SSP and ad server. Our team writes about programmatic advertising, website monetization and buying traffic.
