Full SSP Guide: what is Supply Side Platform (SSP)?

Full SSP Guide: what is Supply Side Platform (SSP)?

Advertisers are increasingly using DSPs and exchanges to purchase their online advertising, but what about publishers? Here’s the Pragmaspace SSP guide on what is SSP, how it works, what features it has and how to choose the suitable one for your business.


Supply Side Platform (SSP) is a technology platform created for publishers to sell, manage, and optimize online advertising space (ad inventory programmatically).

Publishers can sell ad space to Ad Exchanges, Ad Networks, and DSPs and monetize their website and apps.

SSP is an equivalent of the DSP. The main difference is that SSPs used by publishers, and DSPs used by advertisers. Advertisers use DSPs to buy ads as efficiently and cheaply as they can, while publishers do the opposite and use SSPs to maximize the prices of their inventory they’re going to sell.

SSP is an indispensable part of the programmatic ecosystem. With SSPs, publishers can do three big things: open up their inventory to a larger range of potential buyers through real-time bidding, say which advertisers can or can’t purchase their inventory and set the minimum prices for which their inventory can be sold to certain buyers.


Publishers work with SSPs to sell their inventory programmatically. They often have several SSPs set up so that they can create competition between SSPs and drive up the price they sell inventory for. On average, publishers work with around 4-5 SSPs.

  • The publisher signs up with the SSP, and defines the inventory they'll sell through the SSP. This will include parameters such as site names, sections, any data, floor pricing, ad sizes, etc. This can be as simple or as complicated as the publisher likes.
  • The SSP puts the ad request into an auction, which DSPs are invited to participate in. 
  • The DSPs respond with bids, and the SSP returns the winning bid to the publisher.

The publisher will have a few different methods to deal with the bid:

Internal ad-server SSP - ad servers have an SSP built into the ad server, so a winning bid is turned into an ad impression without intervention from the publisher.

Prebid - publishers use prebid or other header bidding technologies - to receive bids from several different SSPs at once, and to choose the best SSP to serve that impression. prebid.org for more information.

Waterfalls and passback - publishers use their ad server to make a request to the SSP, then if the SSP fills with an ad they display it; if not, they run a 'passback' tag, and send the impression off to another SSP to attempt to fill it. Publishers may repeat this several times. Many publishers have moved away from this in favor of the above 2 options.


Supply Side Platforms are constantly expanding their capabilities, but at their core should provide a few key features. So, here they are:

Multiple Demand Sources: The amount of connected DSPs, ad exchanges and ad networks are critically important. This makes your inventory available to the tens of thousands of advertisers. As a result, greater demand brings a higher inventory price. 

Real Time Bidding: It's one of the core Supply Side Platform components. Implementation of RTB algorithms into the platform allows publishers to optimize revenues based on performance, provide transparency and scale while meeting the stringent requirements of response times.

Whitelisting and Blacklisting: This feature allows publishers to control selling their ad space. If for some reason the publisher doesn't want to let certain advertisers buy their inventory there is an ability to block them. It's an important feature to help publishers to protect their inventory from unwanted displays and decide who they want to trade with.

Price Floors Settings: It's a way to help publishers to protect their position on the ad market by closing the gap between the winning bid and the close and, also, forcing ad tech companies to take their fees out of this gap rather than passing it back to advertisers. This entails increasing revenue by pushing the close CPM closer to the winning bid in the second-price auction environment.

Ad Formats Variety: The variety of ad formats gives publishers the ability to achieve their purposes (increase yields, better user experience, higher in-app purchases, etc.) So, the more formats are available on SSP, the faster publishers reach their business goals.

Advanced Reporting: A suite of reports to enable the publisher to see who is bidding, what they are paying, and how much they are buying: reporting is a key for any SSP to understand who values their inventory, and what it is worth on the open market.


What you need will depend on your specific use case, but there are some things you can keep in mind. 

  • The platform should be reliable and have all the control features that you need.
  • It must provide accurate and real-time reporting numbers about your ad sales. 
  • You should also check if the SSP allows you to onboard your existing demand and partnerships, as this may be invaluable to an existing publisher. 
  • Your tech provider may have high entry requirements and may not be able to give you the kind of personalized support.

Finally, how simple or complicated is the setup process? Is the user interface intuitive or does it have a learning curve? All these things should factor in your decision-making process when choosing an SSP.


So, SSPs enable publishers to sell their advertising inventory automatically and in real time. The main goal is to sell inventory for the highest possible price, thereby maximizing your profits and optimizing the process. Changing fill rates, yields, price floors, brand safety – all of this wouldn’t be possible without a fully automated platform.

Here is the basic information for a better SSP understanding from Pragmaspace. We've highlighted the main questions and hope you enjoyed this post.

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