Short answerA DSP works for advertisers and buys ad impressions; an SSP works for publishers and sells them. They meet in an auction: the SSP offers an impression, DSPs bid on it, and the highest valid bid wins. The DSP tries to pay as little as possible for results, the SSP tries to get the highest price for every impression.
"DSP and SSP" is one of the most searched pairs of terms in ad tech, and for good reason: the two platforms are mirror images of each other. This article puts them side by side.
The SSP sends a bid request describing the impression to many buyers.
Each DSP checks the request against its campaigns and replies with a bid or a pass.
The auction selects the highest valid bid above the publisher's floor.
The winning DSP delivers its ad, and the SSP counts the impression and pays the publisher.
Between them there may be an ad exchange, or the SSP may run the auction itself. In both cases one impression travels from the publisher to the advertiser in a fraction of a second.
Do they compete or cooperate?
Both. They need each other — without supply a DSP has nothing to buy, without demand an SSP has nothing to sell — but their incentives pull in opposite directions on price. That tension is healthy: it is what makes the auction work.
Transparency standards keep the relationship honest. Publishers declare authorized sellers in ads.txt, SSPs and networks publish sellers.json, and every impression can carry a SupplyChain object that lists each company it passed through. Buyers use them to avoid spoofed or resold inventory.
Why do some companies run both a DSP and an SSP?
Running both sides on one platform has practical advantages:
Shorter supply path. Fewer intermediaries between advertiser and publisher means less margin lost on the way.
One quality standard. Traffic is filtered once, with the same anti-fraud rules for both sides.
Direct relationships. Advertisers reach verified publishers directly, and publishers get demand without extra resellers.
This is the model Wizads uses: its own DSP for advertisers, its own SSP for publishers and its own ad server. External DSPs and SSPs can also connect to the platform through OpenRTB to buy or sell traffic.
Which one do you need?
You want to promote a product or service and buy traffic → you need a DSP or an ad network with a DSP. Start with our guide on buying website traffic.
You own a website and want to earn from its traffic → you need an SSP or an ad network that monetizes sites. Start with the website monetization guide.
You run an ad platform → you probably connect to both through OpenRTB.
Frequently asked questions
Is an ad network a DSP or an SSP?
It can be either or both. Classic ad networks aggregate publisher inventory and sell it to advertisers; many of them now run a DSP, an SSP or both under one brand.
Who pays the SSP and the DSP?
Usually each platform takes a share of the media spend that passes through it. The exact model depends on the contract and is not standardized.
Can a publisher buy traffic or an advertiser sell it?
Yes, and many do both: a content site may monetize its pages through an SSP and buy traffic for its own growth through a DSP.
Need a quick definition while reading? Check the ad tech glossary.
Wizads is an advertising network with its own DSP, SSP and ad server. Our team writes about programmatic advertising, website monetization and buying traffic.
