Definition
A supply-side platform (SSP) is the software a publisher uses to offer its ad inventory to programmatic buyers, manage floor prices, connect to multiple ad exchanges and DSPs at once, and maximise the yield it earns per impression. When a user loads a publisher's page, the SSP packages the available impression with data about the page and user, sends it to the exchanges, runs or participates in the auction, and returns the winning ad.
The SSP is the sell-side counterpart of the DSP. Its job is to get the publisher the highest sustainable price for each impression while maintaining demand and ad quality.
SSPs differ in the demand they connect to, the controls they give publishers over which advertisers and categories can buy, their fees, and their transparency about the auction mechanics and the take rate between what the advertiser pays and what the publisher receives.
In context
For an iGaming advertiser, the SSP layer matters mainly as the reason inventory quality and brand-safety controls vary. A publisher's SSP settings determine whether gambling ads are allowed on that inventory at all, and open SSP supply — sold with minimal publisher curation — is where much of the low-quality, fraud-prone and brand-unsafe programmatic inventory sits.
Buying through curated deals and allow-lists means transacting with a known set of publishers and their SSPs rather than the open pool.
For affiliates who also own web properties, the SSP is a direct revenue tool: a content or comparison site with display inventory uses an SSP (or a managed alternative) to monetise the traffic it does not send to affiliate offers. The trade-off is between programmatic display revenue and affiliate-link revenue for the same visitor, and a site that fills its best placements with low-yield programmatic ads instead of high-EPC affiliate offers is usually leaving money on the table.
Worked example
An affiliate comparison site enables an SSP to fill display slots on its lower-intent pages while keeping its high-intent review pages purely affiliate-monetised. The split lifts total revenue per visitor by monetising traffic that would not have clicked an affiliate link, without cannibalising the pages where affiliate EPC is high.
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Frequently asked questions
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