Unlocking the Mystery-What Is a Supply Side Platform

Smart AD Selling – What Is a Supply Side Platform?

Digital advertising and information technology have become more and more intertwined as most campaign activities can be managed nowadays through a few clicks within an advanced platform. And that’s the case with supply side platforms as well.   

What is a supply side platform? Read on and find out! 

What Is a Supply Side Platform?  

What Is a Supply Side Platform?

A supply side platform (SSP) represents a specialized software that helps publishers to sell available ad inventory. Basically, SSPs take care of the distribution of ad space in a platform. 

In a way, supply side platforms can be considered the “suppliers” of the ad space selling process. SSPs supply DSPs, ad exchanges, and ad networks with advertising slots to use for delivering their campaigns. And this happens through a bidding process.     

SSPs do not offer available ad inventory on a “first-come, first-served” basis. Instead, such platforms use the RTB (Real-Time Bidding) process to get the most profitable deals for the ad inventory publishers list. Also, SSPs can negotiate a bid in a matter of milliseconds, managing to fill the available ad slots with relevant ads for the lowest price. 

What Are the Main Features of a Supply Side Platform?  

The supply side platform concept was developed to simplify the whole advertising process. Along with ad exchanges, ad networks, and DSPs, SSPs come with great features designed especially for publishers.   

One of the most important is that such software allows delivering ads to a target audience by capping it geographically and based on other critical factors. 

Supply side platforms allocate ad inventory based on bidding. Usually, several advertisers compete for a specific ad space automatically. And at the same time, there is a possibility that some ad spaces remain unused. This is where SSPs step in and ensure that every ad space is used in the most effective way, thus benefiting both publishers and advertisers.   

Thus, when an ad slot is available, advertisers automatically bid for it through a DSP, and the SSP sets a bid range. Afterward, the DSP offers a price that benefits both advertisers and publishers, and the SSP selects the most profitable bid.   

However, if the prices offered are too low, the supply side platform continues to keep the ad slot available until it finds a more profitable bid. Still, this process takes up to a couple of milliseconds; thus, even if it seems a little complicated at first, ad spaces will most certainly not remain unused when a user accesses a website/app.

Supply Side Platform vs Demand Side Platform (SSP vs. DSP)  


As we mentioned before, a supply side platform does not complete the advertising process on its own. The whole RTB process involves more platforms, such as ad exchanges, ad networks, and demand side platforms.   

Strictly referring to SSP vs. DSP, the supply side platform comes with a wide collection of ad slots for sale, while DSP comes with a collection of bids corroborated with the available offers. 

What Is a Demand Side Platform?  

DSP is short for demand side platform, and it is software advertisers use to purchase available ad space automatically. Advertisers can get traffic and impressions on a demand-side platform by using ad inventory from multiple sources at once. Usually, the DSP is looking for inventory from SSPs but also ad exchanges, ad networks, and more. 

SSP vs. DSP  

SSPs and DSPs are different but complete each other. 

First, the platforms have different end-users. While demand side platforms are developed for advertisers who want to place their ads on various websites, a supply side platform serves publishers and helps them sell available ad space to advertisers. 

Who Is a Supply Side Platform for?  

The concept of a supply side platform was developed to streamline the selling of ad space and make online advertising actions more straightforward.

SSPs are made for website and app owners who want to make money by selling ad space. This means they allow advertisers to use the available ad space on their websites or apps.

However, in some situations, SSPs can also help ad networks sell their own available ad inventory. This happens when an ad network cannot sell ad slots directly to advertisers. In this case, the ad network lists its available ad space on an SSP and waits for the platform to fill it with relevant ads.

How Does an SSP Help Publishers?  

SSPs help publishers sell their available ad slots. And usually, an SSP does this by automatically connecting publishers with multiple ad exchanges, ad networks, and DSPs.   

If you wonder how they do that, imagine that a publisher lists their ad inventory on an SSP. The SSP communicates with ad networks, ad exchanges, and DSPs to find ads to fill the ad slots. These platforms have specific ads listed by advertisers. 

The SSP negotiates with its complementary platforms to find the best ads for the ad slots it has to fill. When the SSP finds an ad that brings the publisher a significant bid, it displays the ad in the available ad slot.    

As a publisher, when you are connected with multiple advertisers at once, you can receive several biddings simultaneously, and the supply side platform decides which one is the most profitable for you.     

Also, the software sets the highest price possible for your ad space, thus ensuring that you maximize your revenue. Furthermore, this process usually takes some milliseconds, and this is another great benefit of SSPs.     

A supply side platform takes the work previously done by multiple marketers, making it easier, quicker, and more efficient. And besides streamlining the process, the SSP also contributes to delivering a better user experience, and this can also be helpful for publishers. 

After all, there is a possibility that some users are driven away from a website due to an inappropriate or misplaced ad. Thus, the SSP ensures that such unfortunate events are reduced as much as possible. 

Top Supply Side Platform Examples  

Top Supply Side Platform Examples

Usually, where marketing goes, Google follows. And the company has developed some pretty useful marketing tools. Google Ad Manager is one of the most popular supply side platforms in the world at the moment.    

SSP Google Ad Manager

Google Ad Manager supports multiple ad networks, including Ad Exchange, AdSense, and other third-party platforms. With a simple setup and an intuitive interface, Google Ad Manager includes valuable features, such as granular ad targeting, creating teams, highly detailed reports, and open bidding.   

ssp ad manager

Moreover, Google Ad Manager offers a pretty helpful feature called Protections. This allows you to set various rules so that the advertisers filling the available advertising inventory comply with your basic requirements, thus helping websites maintain relevancy.


Magnite is currently the largest and most popular independent supply side platform example. Although available for multiple channels, Magnite focuses on CTV (connected TV) demand.    

Previously called Rubicon, Magnite was launched in 2020 after a merger that aimed to develop innovative technologies for the buying and selling advertising inventory.     

Thus, the company has created a great real-time cloud and big data computing system, reaching trillions of monthly transactions with an extremely short transaction processing time.     

Magnite allows users to manage campaigns, check detailed ad campaign analytics, and manage ad inventory.

magnite ssp


Xandr (previously called AppNexus) is an extremely helpful platform for those aiming to connect with multiple DSPs to sell their ad inventories. Xandr uses prebid-powered header bidding technology, deal capabilities, and curated premium demand.     

Though some users believe the platform could be more user-friendly, Xandr still offers extremely detailed yield analytics, data-driven yield optimization, demand channel management, and many other advanced and valuable tools.   


PubMatic is usually recommended for independent publishers, helping them control and increase their revenue.     

The platform aims to match premium demand to a publisher’s ad inventory by optimizing audience access across screens, channels, and ad formats. Thus, PubMatic matches an advertiser’s needs to a publisher’s inventory.     

PubMatic has also developed innovative technology for omnichannel monetization, as well as built-in ad quality tools and private marketplaces for advertising inventory.     

PubMatic ssp

Final Thoughts  

  • Advertising has reached a point where several processes can be streamlined. And this is where a supply side platform can help.     
  • A supply side platform consists of software that enables publishers (website or app owners) to sell their available advertising space to those aiming to place their ads somewhere (advertisers).    
  • The entire process of real-time bidding (RTB) unites three types of platforms: ad exchanges, DSPs (demand side platforms), and SSPs (supply side platforms). Such software can help advertisers and publishers deliver ads in suitable places for both parties. Thus, advertisers get impressions, and publishers increase their revenue.     
  • Among the best supply side platforms available currently, some of the most popular are Google Ad Manager, Magnite, Xandr, and PubMatic.