DSP vs SSP: demand-side and supply-side platforms explained
A DSP buys ad impressions for advertisers, an SSP sells them for publishers, and they meet in a real-time auction. Here is what that means for iGaming affiliates.
In programmatic advertising, a demand-side platform (DSP) is the software advertisers and media buyers use to bid on ad impressions. A supply-side platform (SSP) is the software publishers use to sell them. The two meet in an automated auction for every single impression, settled within a deadline measured in milliseconds.
For an iGaming affiliate the short version is this: you buy through a DSP, the publisher sells through an SSP, and gambling rules apply on both sides before your ad can run.
What is a demand-side platform (DSP)?
A demand-side platform is the buying tool. A brand, an agency or a media buyer connects one account to many exchanges and SSPs, then sets the rules in advance: audience, placements, maximum price, daily budget, frequency cap and the conversion that counts as success. After launch, the DSP applies those rules to every impression it is offered and decides whether to bid and how much.
That split is the point of a DSP: people set strategy, budget and creative, and the software prices each impression, at a volume no buying team could handle by hand.
DSPs differ in two ways that matter to an affiliate:
Access. On a self-serve DSP your own team builds and runs campaigns. On a managed service, the DSP's staff or an agency runs them for you, usually with a minimum spend. Enterprise DSPs often grant self-serve seats under a contract rather than to anyone with a card.
Specialism. Omnichannel DSPs buy display, video, audio and connected TV from one seat. Others focus on mobile apps or on CTV alone.
What is a supply-side platform (SSP)?
An SSP is the selling tool a publisher (a website, an app or a streaming service) uses to auction its ad space to as many buyers as possible. The supply-side platform turns each impression into a bid request, sends it to the DSPs and exchanges the publisher has approved, and accepts the best bid that clears the publisher's rules.
Those rules live in the SSP:
Price floors. The lowest price the publisher will take for an impression, which can differ by placement, format or buyer.
Header bidding. Code on the page asks several demand partners for bids before the publisher's ad server makes its final choice, so more buyers compete for each impression. Prebid is a widely used open-source framework for this.
Deals. Besides the open auction, a publisher can offer private marketplaces or fixed-price programmatic deals to selected buyers.
Ad quality controls. Blocklists for advertisers, domains and whole ad categories. This is where a publisher can switch gambling off.
How a DSP and an SSP work together
A DSP and an SSP work together through a real-time auction: the publisher's SSP offers each impression to connected DSPs, each DSP decides whether to bid and how much, and the best eligible bid wins within milliseconds. Follow one impression in the open auction:
A user opens a page or an app that has an ad slot.
The publisher's SSP builds a bid request. It can include the slot size and format, the site or app, approximate location, the device and any audience signals the publisher is allowed to share.
The request goes out through an exchange to connected DSPs, usually in OpenRTB, the IAB Tech Lab standard for communication between ad buyers and sellers.
Each DSP checks the request against its advertisers' campaigns. When one matches, the DSP prices the impression, typically by estimating how likely it is to convert and multiplying that by what the advertiser says a conversion is worth, then returns a bid with a creative.
Late bids are dropped. Google's exchange, for example, waits 80 to 1,000 milliseconds, depending on format and auction type.
The highest eligible bid above the floor wins, the ad is served, and the winning DSP logs the cost against the campaign.
How much the winner pays depends on the auction rule. Many exchanges used to run second-price auctions, where the winner paid roughly the runner-up's price. In 2019 Google announced that Ad Manager would move to a unified first-price auction, where the winner pays exactly what it bid.
Under first-price rules every cent of overbid is paid, so DSPs shade their bids: a model predicts how the odds of winning fall as the price drops and lowers the bid where the saving outweighs the lost wins. A 2021 KDD paper on the Verizon Media DSP documents one such system and links it to the move to first-price auctions that most exchanges and SSPs made from 2019. Different shading models are one reason two DSPs can pay different prices for the same audience.
DSP vs SSP: the key differences
The key difference is whose side each platform works for: a demand side platform bids for advertisers and tries to buy the right impressions at the lowest price that still wins, while a supply-side platform sells for publishers and tries to get the most for each impression.
| DSP (demand side) | SSP (supply side) | |
|---|---|---|
| Job in the auction | Bids on impressions | Offers impressions and picks the winning bid |
| Used by | Advertisers, agencies, media buyers | Publishers: sites, apps, streaming services |
| Counts as a win when | It buys the right impressions at the lowest price that still clears | Each impression sells for the most the market will pay |
| Settings | Audiences, bids, budgets, frequency caps, conversion goals | Price floors, demand partners, deals, blocklists |
| Data it leans on | The advertiser's audience lists and conversion data | Page and app context, the publisher's own audience data |
| Where gambling rules bite | Platform policy, advertiser certification, geo-targeting | Category blocks and the publisher's own ad standards |
| Examples | The Trade Desk, Amazon DSP, Google Display & Video 360 | Magnite, PubMatic, OpenX, Google Ad Manager |
"DSP" and "SSP" describe a role, not a business model. Some large ad-tech companies run both sides: Google sells a DSP (Display & Video 360) and a sell-side platform (Ad Manager). Every platform in the chain is paid out of the media spend, so get the fee structure of any DSP or managed-service provider in writing.
Where ad exchanges, ad networks and DMPs fit
Ad exchanges, ad networks and DMPs sit around the DSP and SSP: the exchange hosts the auction, a network resells publishers' space at its own price, and a DMP supplies audience data. Walled gardens skip third-party DSPs and SSPs altogether.
Ad exchange. The marketplace where the auction actually runs. Many SSPs operate their own exchange, so the two terms often overlap in practice.
Ad network. A reseller that represents many publishers and sells their space at its own price, often per click or per thousand impressions, so you see the network's rate, not each auction. Many push, pop and native traffic sources work this way.
DMP. A data management platform holds audience segments for targeting and passes them to a DSP. It never buys media itself.
Walled gardens. Meta, Google Ads and Reddit Ads sell their inventory through their own ad managers and auctions, so you buy there directly rather than through a third-party DSP and SSP.
What this means for iGaming affiliates
In affiliate marketing you buy traffic, so your tool is a DSP. You would only touch an SSP if you also run a publisher site or app and sell its ad space. Most affiliates reach programmatic through a self-serve seat, a managed service or a network that resells programmatic inventory.
Gambling changes the setup in five places.
Platform policy comes first. Google's Display & Video 360 applies the Google Ads gambling and games policy. For the United States, that policy lists sports betting, online casinos and horse racing as eligible with Google certification, and says advertisers must be licensed by the state entity in certain states where gambling is legal. It also sets age and state limits (no targeting of users under 21 or outside the states where the advertiser is licensed) and requires a warning about compulsive gambling with help information; read the current text to see which product each limit covers. Content that promotes gambling is certified separately and may only target the states named in that certification, so check which category your landing pages fall into. Other DSPs publish their own rules; check the current policy before you plan spend.
Inventory shrinks. Publishers can block gambling in their SSP, and streaming services set their own terms. Netflix, for example, requires pre-approval for every gambling advertiser, asks sports betting and online casino advertisers for valid operator licences, and allows targeting only in states where they are pre-approved, with no national campaigns. Expect less reach than the DSP's headline numbers suggest.
Geo-targeting is a compliance control. State targeting has to match where the operator you promote is licensed, and each creative needs the licensed brand and the responsible-gambling message that the operator and the platform require.
Conversion data closes the loop. A DSP can optimise for impressions or clicks from day one, but to bid toward depositors it needs conversions sent back from your tracker, usually through postback (S2S) tracking. Set the conversion value from what the operator actually pays you under CPA or RevShare, and compare cost per first deposit against it.
Breaking the rules ends accounts. Running gambling creatives without approval, or declaring the wrong ad category, gets creatives rejected and seats suspended.
This section summarises platform policies as published on October 28, 2026, not state law. State advertising rules for sportsbooks and casinos apply on top, and nothing here is legal advice.
Examples of DSPs and SSPs
Well-known DSPs include The Trade Desk, Amazon DSP and Google Display & Video 360, and well-known SSPs include Magnite, PubMatic, OpenX and Google Ad Manager. They are listed neutrally below, not ranked or endorsed.
Demand-side platforms
The Trade Desk: an independent demand-side platform, not tied to one publisher's inventory.
Amazon DSP: Amazon's demand-side platform for buying Amazon-owned and third-party inventory.
Google Display & Video 360 (DV360): Google's enterprise DSP; its users must follow the Google Ads gambling and games policy.
Supply-side platforms
Magnite: an independent SSP for display, video and CTV inventory.
PubMatic: an independent SSP for web, app and CTV publishers.
OpenX: an independent SSP that also runs its own exchange.
Google Ad Manager: Google's publisher platform: an ad server plus its own exchange.
There is no best demand-side platform for every affiliate. When you compare DSPs, ask four questions: will it accept gambling advertisers in your states, how much inventory is left after category blocks, can it take your postback conversions, and what are the minimum spend and fees?
FAQ
What is an SSP in advertising?
An SSP, or supply-side platform, is software that publishers use to sell ad impressions automatically. It offers each impression to many buyers at once, applies the publisher's price floors and ad rules, and accepts the best bid.
What are examples of SSPs?
Magnite, PubMatic, OpenX and Google Ad Manager are common supply-side platforms. Publishers often run several at once through header bidding.
What is the difference between a DSP and an SSP?
A DSP works for the buyer and aims to win the right impressions at the lowest winning price; an SSP works for the seller and aims for the highest price. They meet in a per-impression auction.
Do affiliates need a DSP, or is an ad network enough?
Many affiliates start on ad networks or walled gardens because they are self-serve and cheaper to test. A DSP makes sense when you need reach across many publishers or CTV, or more control over data and placements, and can meet its minimums and policy checks.
Can you advertise gambling through a DSP?
You can advertise gambling through some DSPs, with approval. Google's DV360 follows the Google Ads gambling policy, which in the US requires certification and state licensing, with state-level targeting limits. Other DSPs set their own rules, so check the current policy before you spend.
Is a DSP the same as an ad exchange?
A DSP is not the same as an ad exchange. The exchange is the marketplace that runs the auction; the DSP is the buyer's software that bids in it, usually across many exchanges at once.
Sources
IAB Tech Lab, OpenRTB 2.6 specification
Google Authorized Buyers, Real-time Bidding guide
Google Ad Manager blog, first-price auction update, May 10, 2019
Prebid.org, Introduction to header bidding
Google Ads Help, Gambling and games policy
Netflix, Ads policy: gambling
