SSP What is Supply Side Platform - Admixer blog

SSP — What Is a Supply-Side Platform? A Guide for Publishers

Author: Elena Storchak, Director, Supply Partnerships at Admixer
6 August 2020

Programmatic is becoming a prevailing model for monetizing media assets for digital publishers. Despite the slow adoption of programmatic in the developing markets, globally, publishers recognized the benefits of automatically selling their ad spaces through real-time auctions. This method eliminates the redundant manual process of establishing direct advertising contracts, and allow publishers to manage ad spaces effectively, and get the best price for their inventory.  

Joining the programmatic ecosystem allows publishers to speed up their inventory sales and adopt data-driven strategies to manage and monetize their audiences. The key to success in this marketplace is choosing a reliable supply-side platform (SSP). Let’s get to the bottom of this solution, review SSP definition, and outline how to select an SSP partner.

What is an SSP?

What is an SSP - Admixer Blog

A supply-side platform (sometimes referred to as sell-side platform or SSP) is an adtech solution for publishers to monetize traffic from their site, app, game, or any other digital platform. A supply-side platform is a gateway into the programmatic ecosystem that enables automatic auctions for the ad inventory and connects publishers to multiple ad exchanges, demand-side platforms (DSPs), and networks at once.

The SSP’s main goal is to optimize yield for publishers and ensure the most profitable placements with timely reporting and analytics. 

Why do publishers need a supply-side platform? 

Frequently regarded as sell-side platforms, SSP is a critical piece of the programmatic ecosystem that enables publishers to auction off their audience’s impressions. Supply side platform connects publishers with multiple potential buyers and offers ad placements for bidding. The functionality of the SSP goes beyond its definition, and offers a whole range of services for publishers and app developers. 

Supply-side platform offers publishers a dashboard for ad inventory management and campaign supervision. It is a complete interface that allows to assess the campaign details in real-time, change the format of ad spaces, and control cost per thousand impressions or CPM. 

Instead of juggling multiple advertising arrangements, SSP grants publishers a platform to work with multiple campaigns and several demand partners in one place. SSP seamlessly integrates with agency trade desks, demand-side platforms, ad networks, and even data exchanges. 

How were SSPs invented?

Before SSPs, the media buying happened through ad networks, which aggregated thousands of advertisers and offered their inventory to advertisers. Networks did all the ad inventory management, negotiate with advertisers, and boosted publishers’ revenue by attracting diverse demand. 

Ad network was an adequate arrangement for advertisers until it faced the problem with scaling. Global advertisers needed audiences across various geos and content niches, while most networks had limited scope. Furthermore, various ad networks had different integration methods and issues with inventory sales to external sources. 

Supply-side platform became a natural solution for this scaling platform. It allows advertisers to use an auctioning marketplace, instead of negotiations with multiple ad networks with fragmented audiences. Advertisers can now buy impressions at scale, centrally, without the need to engage with relationships with various ad networks. 

Ad network - Admixer blog

What is the difference between SSP and Ad exchange? 

Supply side platform works on behalf of publishers, analyzes their audiences, organizes the inventory into thematic packages to sell it to advertisers. The SSP meaning is to maximize revenue for publishers. Similarly to DSP, which works for the benefit of advertisers to get the most cost-effective ad placements. 

In contrast, ad exchange does not have a goal of maximizing the revenue for any side. It’s a mediator that receives a commission for the connection of different parties. Nowadays, there are only a few classic ad exchanges, and most of them have some of their inventory. Thus, the line between SSP and ad exchange is blurred. 

How SSP works

Supply-side platform acts on behalf of the publisher in the programmatic marketplace and automatically negotiates deals for them. Publishers put SSP ad tags on their web pages, and media buying happens automatically through one of the programmatic buying methods. Mobile SSP uses SDK to identify audiences in the app environment. 

Things revolve around the concept of bid – price for an ad impression. In the bid request publisher is sending the information about ad opportunity, while in the bid response advertiser sends information about the ad they would like to show. The highest bid in the auction is granted the ad impression.

Bid request:

  • Info on ad opportunity 
  • (type, size, etc.)
  • desired price for an ad
  • Info on the user (country, IP, device, etc.)

Bid response:

  •  bid price advertiser is ready to pay for this ad opportunity
  • ad markup (the actual creative)
  • info on the ad (type, size, duration, tracking tools, etc.)

Sell side platform evaluates the ad request, matches it with the appropriate inventory, and conducts a negotiation that takes up to 30 milliseconds.

Even though trading happens automatically, publishers have several procedures to ensure profitable placements. Supply side platfrom protects the publisher’s revenue with a pre-set minimum for impression price. Publishers can establish the price floor for the inventory, and the bid responses will never fall below it.   

Additionally, SSP has several provisions to protect the integrity of its supply partners. Publishers can utilize whitelists and blacklists of advertisers to safeguard their site from ill-suited ads and fraud. For example, a publisher focusing on adolescent content can prohibit alcohol or gambling brands from displaying ads on websites. 

How SSP sells the inventory

SSP provides options for publishers to sell their inventory programmatically. Publishers may have some premium inventory, which they can reserve for direct deals, sell specific placements in the private marketplace to large-scale advertisers, and auction off the remnant traffic through real-time bidding, either oRTB or header-bidding. More on that, you can read in our guide to programmatic. 

Programmatic Buying Methods - Admixer Blog

5 key features of supply-side platforms 

Let’s go over the main benefits of sell side platform for publishers and how they can boost performance, revenue, and accountability in media buying. 

Format variety

SSPs significantly ease the integration with advertisers since they provide a common procedure and ad serving protocol, and don’t require additional adjustments. They can specialize in a particular ad format, for instance, video SSP or mobile SSP. However, most supply-side platforms strive to provide the work with diverse ad formats. 

Previously, SSPs mostly worked with web banners; right now, they serve ads in different environments from in-app and in-game to CTV and DOOH. Usually, they support most of the IAB advertising formats, such as native ads, video ads, and playable ads, etc. 

Ad formats - Admixer Blog


SSP opens the door for publishers into the new era of media trading – programmatic. According to estimates by eMarketer, more than 86% of display ads in the US in 2020 will be traded programmatically.

Programmatic prevailed due to its data-centric approach – audience segmentation and management. Instead of offering blocks of advertising in particular resources, it provides deep insights into the consumers of content and offers audiences instead. Trading individual impressions proved to be beneficial for both sides, publishers with unique audiences get a real-value for the ad placements, while advertisers got much more precise targeting options. 

The auctioning model gives SSP meaning,  facilitates transparency in the media marketplace, and enables advertisers to get a clear picture of the ad placement they are buying, and flexibly manage their campaigns and reach. 

Data-rich impressions

Supply-side platform organizes publishers’ data to offer precise targeting options for brands and companies. With the help of the supply side platform, publishers offer impressions with extensive context based on user behavior, affinities, and preferences. 

For instance, the user is a hiking enthusiast, who is just dipping the toes in this hobby, and checking reviews for tents and hiking equipment. SSP will label this impression, place it into the coherent audience segment, and offer it to the camping shops and tent dealers. 

SSPs also add the geographical dimension to impressions by supplying them with geolocation data. Users from desktop devices can be traced through the IP, while their data is usually accurate only on a country level, you can’t target them based on city or region. 

Mobile SSP  can provide a more precise geotargeting depending on the type of connection of the device to the web:

Ad geotargeting - Admixer Blog

Audience profile

Supply side platform not only adds another layer of meaning with geographical and behavioral data but also helps to build a comprehensive portrait of the audience. Leveraging demographic information with intricates of user behavior allows advertisers to understand the intent of users better, and define potential customers.  

With information on users’ activity, favorite content categories, frequency of interaction with particular topics, allow advertisers to understand how to approach specific segments of the audience, and tailor ad specifically for their tastes.

At the same time, publishers can get a higher CPM for in-demand impressions and niche audiences. SSPs usually enhance their data management capabilities by partnering with a reliable data management platform (DMP). This platform has additional instruments and connections to external sources of data for advanced traffic analysis, audience segmentation, and upselling impressions with additional data. 

Data safety 

Privacy is becoming a central issue for digital advertising. Legislators across the world raise concerns regarding tracking user behavior and collecting personal data. A wave of regulations, such as GDPR and CCPA, undermined traditional data collection and targeting instruments. 

However, the supply side platform has a couple of features that can help with this issue. For instance, a supply side platform can craft anonymous personas based on the publisher’s data, without invoking any personally identifiable information. It consists of demographic information paired with the broader context, content habits, daily activities, that give insight into the user character and intent. Personas allow SSP to disclose exhaustive user information to prospective buyers without compromising their anonymity and privacy. 

Benefits of SSP for publishers 

Reporting: SSP provides the publisher with extensive information on the demand for their inventory. Supply side platform can give details on how much the inventory was bought for, what kind of advertisers are bidding, and what type of placements convert the most. Granular reporting on the audience on audience performance and yield from ad placements allow publishers to get profound insights into their worth on the market, and optimize their strategy accordingly. 

Flexibility: While working with SSP, publishers do not have to commit to a single source of demand. Instead, they can mix and match their inventory between auctions on Ad exchanges, preferred deals, or private marketplaces. By connection to different sources of monetization, publishers can maximize their yield. For instance, the publisher has an audience segment that is in-demand for beer brands. He can sell this audience through preferred deals and monetize the remaining inventory through an oзRTB auction. 

Yield Optimization: Frequently, publishers witness price depreciation of their inventory, if there are not enough bidders from a particular ad network or ad exchange. Modern SSPs support header bidding technology that allows them to receive bids from multiple advertisers simultaneously, in contrast to openRTB or waterfall where they go into the auction in turns. By instantly connecting diverse advertisers, the sell side platform helps publishers to achieve the maximum possible yield. 

Issues with SSPs 

In 2019, about 1 in 100 ad impressions were malicious or disruptive for the viewers. Despite the fact that publishers are rarely responsible for bad ads, they are the last stop in the supply-chain and frequently get the blame. Those ads can compromise publishers’ reputation, encourage the use of ad blockers, hurt overall yield from advertising, and cause sanctions from regulators.

In the complex programmatic ecosystem, it is often hard to determine the origin of the harmful impression. Supply side platform, as the main point of contact of the publisher with the programmatic ecosystem, is responsible for filtering those ad requests. However, various SSPs have different mechanisms for checking traffic quality and may lack the capability to recognize malicious impressions. 

Publishers should choose SSP, wisely, and assess its controls and safety practices. For instance, Admixer.SSP is partnered with 4 renowned ad quality/verification vendors to ensure brand safety for publishers: 

  • Ad lightning 
  • The media trust 
  • Geoedge 
  • Pixalate 

How to choose SSP

Supply side platforms is a competitive market, with thousands of vendors trying to make a difference and offering additional value. On average, publishers use 3-4 different SSPs to get diverse sources of demand. 

Most of all publishers value the volume of demand that a sell side platform can provide, as well as a comprehensive interface with reporting and detailed analytics. Another critical thing is the quality of ads, SSPs usually partner with outside vendors to filter out spam, contentious ads, and fraud. 

How to choose SSP - Admixer Blog


DSP or demand-side platform is another critical piece of programmatic infrastructure that works as a gateway for advertisers. It allows ad networks, brands and agencies to buy media across multiple channels through the real-time actions. 

DSP put forward a bid response with the advertiser’s requirements price, audience, and context. DSP is also a data-centric solution that can track and optimize marketing campaigns and adjust creatives in real-time.

How DSP and SSP work - Admixer Blog


Adoption SSPs as a new standard for digital advertising resolved some critical scaling issues of the ad networks. Supply side platform is the next mature stage of the market that enables data-driven media trading. 

Advertisers now can buy audiences across multiple channels, platforms, and geos, without complex integrations and negotiations. Publishers got access to a truly international market and can offer their supply at market prices to global players. SSP live up to its definition and represents publishers in the most effective way. 

Supply side platform, as well as DSP, is a new word in the automation of media buying that streamline the ad placements and remove complex negotiations through RFPs. By significantly limiting behind-closed-door deals, SSPs strengthen accountability and trust in the marketplace.

SSP is not only a marketplace but also a data-driven instrument that enables precise audience segmentation, user analysis, and data management. With SSP, publishers can derive a deeper understanding of the audience, letting advertisers better target campaigns and find the most potent audiences. 

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