DSP and SSP in Programmatic Advertising: Who's Who, and Who Gets Paid

Two platforms, two different customers

A DSP and an SSP run on the same underlying auction, but they are built for opposite people and optimize for opposite things. A DSP is the advertiser's tool: log in, set a budget and targeting, and the platform bids into thousands of auctions a second on the advertiser's behalf, trying to buy the cheapest impression that meets the campaign's goals. An SSP is the publisher's tool: it takes a website or app's unsold inventory and offers it into as many demand sources as possible, trying to sell each impression for the highest price it can get.

Neither platform buys or sells anything on its own account. Amazon DSP is a demand-side platform — the Demand-Side Platform kind, not the Delivery Service Partner courier franchise that shares the initials — used by advertisers to buy display, video, and audio inventory both on Amazon's own properties and off them. On the sell side, publishers who want Amazon's demand connected to their own inventory work with Amazon Publisher Services, a separate product built for that role.

Where the money actually goes: a real worked example

Most explainers stop at the auction mechanics and never show what each side actually keeps. In 2020, ISBA — the UK's trade body for advertisers — and PwC ran the most detailed audit of the programmatic supply chain that has ever been made public: real invoices, real impression logs, and real fee data pulled directly from 15 advertisers, 12 agencies, five DSPs, six SSPs and 12 publishers, covering roughly £0.1 billion of actual UK programmatic spend.

Here is what they found, for every £100 an advertiser spent: an agency fee took about £7. The DSP's own fee and the demand-side technology around it — ad serving, brand-safety verification, and data costs — took roughly £18 combined. The SSP's fee took about £8. Publishers kept £51. And £15 — the "unknown delta" — could not be traced to any named party in the chain at all, roughly a third of every pound spent on technology and fees rather than working media. Individual publishers in the study ranged from keeping 49% to keeping 67% of the advertiser's spend, depending on how many intermediaries sat between them and the buyer.

What sits between them: the ad exchange

A DSP and an SSP don't talk to each other directly on the open market — an ad exchange sits between them, running the auction and enforcing its rules. Most exchanges run on OpenRTB, the bid-request standard published by the IAB Tech Lab, which is why a DSP built by one company can bid into an exchange run by a completely different one without custom integration work for every pair. The exchange itself doesn't buy or sell inventory; it forwards bid requests from the SSP to every connected DSP, collects the responses, and awards the impression to the winner, all inside roughly 100 milliseconds.

This is also where private deals live. Not every transaction runs through the open exchange's blind auction — a publisher and an advertiser can agree in advance on a private marketplace deal or a fixed-price programmatic guaranteed deal, still executed through the same DSP-to-SSP plumbing, just without the open bidding.

The mistake that keeps the unknown delta alive

The ISBA/PwC study's most useful finding wasn't the 51% headline — it was that the study could only match 31 million of the 267 million impressions it started with, about 12%. The rest couldn't be traced end to end because data formats, permissions, and logging conventions differed at every hop in the chain. That's the practical version of the DSP/SSP relationship most buyers never see: the fee structure is not opaque because anyone is hiding it, it's opaque because nobody standardized how to report it, and a buyer who never asks for a full-path reconciliation will never notice the gap.

The honest version of this question, applicable to any DSP including Amazon's: ask what percentage of your media budget actually reaches the publisher versus what pays for the platforms in between, and ask whether that number is measured or estimated. If a vendor can't answer that question with a specific figure, the honest read is that they haven't measured it either — which is common, not necessarily disqualifying, but worth knowing before you assume the number is small.

What to check when the math doesn't add up

If a campaign's delivered impressions or reach look lower than the budget should buy, work through the chain in this order. First, check the DSP's own fee structure — a percentage-of-spend technology fee compounds with every other fee in the chain, unlike a flat platform fee. Second, check how many resellers sit between the DSP and the actual publisher; SSP-to-SSP reselling was flagged in the ISBA study as one likely contributor to the unknown delta, because the same inventory can pass through more than one supply-side platform before it's sold. Third, check whether viewability and invalid-traffic filtering is happening pre-bid or post-bid — pre-bid filtering avoids paying for bad inventory at all, while post-bid filtering pays for the impression and then discounts it in reporting, which is a very different economic outcome for the same reported "clean" number.

Where Dr. DSP fits

Dr. DSP is Amazon DSP run as a managed product by Full Circle, which has managed more than $500M in revenue across 100+ brands. Across 27 advertisers over 31 days in summer 2026, our own Amazon DSP book returned 5.12x on $732,916 of spend — a number that, per the mechanics above, already has agency, DSP, and technology fees baked into the delivered result rather than sitting as a separate line a buyer has to go find. Whether or not that's the right setup for a given brand, the DSP/SSP relationship underneath it works exactly as described above, on any platform.