What is a Supply-Side Platform?

Naomi Khor
January 27, 2021
May 16, 2024

Advertisers are increasingly using DSPs and exchanges to purchase their online advertising, but what about publishers? What are supply-side platforms (SSPs) actually for? And why are SSPs commonly referred to as yield-optimization platforms?

Let’s take a closer look and find out.

Table of content:

• What Are Supply-Side Platforms (SSPs)?

• How Do Supply-Side Platforms Support the Ad Selling Process?

• What Are the Main Features of an SSP?

• How Does A Supply-Side Platform (SSP) Work?

• What Is the Difference Between an SSP and DSP?

• How Do SSPs Help Publishers?

• What Are the Main SSP Companies in the Programmatic Ecosystem?

What Are Supply-Side Platforms (SSPs)?

What Are Supply-Side Platforms (SSPs)?

A supply-side platform (SSP), or sell-side platform, is an advertising technology (adtech) platform used to coordinate and manage the supply and distribution of ad inventories. SSPs help digital media owners and publishers sell ad space.

SSPs are a key part of the real-time bidding (RTB) process within programmatic advertising, enabling publishers to optimize yield by simultaneously connecting their inventory to multiple ad exchanges and demand-side platforms (DSPs).

By opening up impressions to as many potential buyers as possible, the publisher’s site can maximize the revenue they receive for their inventory. For this reason, SSPs are sometimes referred to as yield-optimization platforms.

‍How Do Supply-Side Platforms Support the Ad Selling Process?

SSPs play a key role in RTB media transactions. There are a number of processes and requirements SSPs handle, including:

  • Real-time bidding transactions. SSPs sell a publisher’s ad space to DSPs in an automated fashion via an ad exchange.
  • Ad-network optimization. Since SSPs sell individual ad impressions, they provide publishers with more control over their inventory. Publishers can see who is paying for their inventory on the impression level and optimize their ad requests accordingly.
  • Frequency capping. SSPs and DSPs work together to run frequency capping, which is the process of recording the number of times a specific visitor is shown a particular advertisement and then limiting the number of times that visitor sees that ad.
  • Relevancy. With an SSP, the publisher can make sure that only relevant ad networks are considered for their available ad space.

What Are the Main Features of an SSP?

  • User interface – allows publishers to leverage the SSP to their advantage as they sell impressions.
  • Analytics and reporting – enables publishers to get full transparency about the performance of their ad inventory, including fill rates, clicks, and impressions.
  • Header bidding – most SSPs incorporate header bidding functionality, allowing publishers to obtain bids from multiple DSPs, and manage their header bidding wrappers and demand partners.
  • Yield optimization – aims to increase revenue for publishers by improving fill rates, setting floor prices, and managing auction mechanics.
  • Inventory and campaign management – allows publishers to manage different types of ad inventory and block certain types of ads.

How Does A Supply-Side Platform (SSP) Work?

How does a supply side platform (SSP) work?

Traditionally, publishers worked with human sales teams and media buyers to manually assign ads to spaces. However, owing to large audiences and the rising number of digital marketers all competing for the same ad space, manual placement is no longer efficient.

Now, SSPs utilize programmatic advertising technology to pair with demand-side platforms (DSPs) to evaluate advertisers, take stock of publishers’ total inventory, set the bidding range, and then make recommendations for the best match for each space. 

SSPs allow publishers to filter digital ads by the advertiser, ad format, target audience, and other criteria, as well as set different rates for ad spaces.

The process takes place in multiple micro-transactions across the digital advertising supply chain. The SSP can make the inventory available to buyers directly or via ad exchanges, DSPs, and agencies.

Once agreed upon, a pixel code is placed on a publisher’s page to track audience data and visitor behavior. The code delivers anonymous data about visitors and the actions that they take. It is programmed to maximize the value that publishers receive from an impression of an ad. 

What Is the Difference Between an SSP and DSP?

The difference between supply side platforms (SSP) and demand side platforms (DSP)

As mentioned above, the supply-side platform (SSP) is an adtech platform used by publishers to connect their inventory to ad exchanges. An SSP allows publishers to filter ads by the advertiser and other criteria, as well as set different rates for ad spaces to define the cost.

DSP refers to the demand-side platform. It allows the buyers of digital ad inventories to manage multiple ad exchanges via one interface.

The buyers commonly include trading desks, agencies, or advertisers directly. The DSP must plug into an SSP to enable the buyer to bid on digital inventory. 

Simply put, a DSP and an SSP connect to different parts of the programmatic ecosystem. A DSP is a tool used by advertisers to help organize ad-buying, whereas an SSP is used by publishers to automate the sale of advertising space, which is the supply-side of the demand-side platform.

How Do SSPs Help Publishers?

Supply-side platforms (SSPs) help open advertising inventory for bidding to multiple ad buyers on various ad exchanges and networks and demand-side platforms (DSPs).

SSPs help establish a connection with a larger number of advertisers and manage the complexity of working with multiple ad networks or ad exchanges at once.

Additionally, a good supply platform should be making your inventory available to a wide variety of buyers in the market for the maximum price.

Your daily goal would be to sell all your inventories for the highest price.

Working with a high-quality supply-side platform guarantees a win for your business because multiple high-quality demand sources ensure inventory is sold at the highest price.

For publishers, the main advantages of SSPs include:

Granular Reporting

Reporting and data analysis is extremely important for a successful business to understand what is working well, and what is not.

To maximize profits, you need to know how much you are earning from your inventory and its value.

A good platform will provide you with an in-depth reporting system. This will help you make the right decision on how best to sell your inventory or how to optimize your yield.

Dynamic Price Floor

An exceptional SSP should give you the ability to set soft and hard price floors at a minimum CPM. This flexibility will allow you to maximize your revenue.

Aggregation of Multiple Networks

SSPs can connect to multiple networks, ad exchanges, and DSPs, allowing more buyers to take part in the real-time bidding process and enabling publishers to achieve better yield.

Simple and Transparent

The programmatic landscape is quite complex, although its purpose is to simplify the advertising process. A supply-side platform should be simple to use, easy to integrate, and provide all data to analyze your performance.

Brand Safety

Since SSPs can be set to only offer inventory to specific buyers or through certain channels, they can offer better brand safety by blocking unwanted ads from showing on your website.

What Are the Main SSP Companies in the Programmatic Ecosystem?

SSPs are one of the leading players in the online advertising ecosystem and play a key role in real-time bidding (RTB) media transactions.

They connect to ad exchanges, ad networks, data-management platforms (DMPs), and demand-side platforms (DSPs) to sell ad inventory on behalf of publishers, such as websites and app owners.

Those platforms help publishers manage the complexity and volatility of the programmatic ad-buying process, especially when managing multiple ad networks and their diverse requirements and limitations.

There are many SSP companies. Choosing an SSP company might depend on the strategy, goals, budget, type of campaign, and targeted audience. That said, finding the best one for your specific needs is extremely important to help your business succeed.

Throughout the years, Publift has worked with many different partners to test their performance and assess their value to publishers.

The SSPs that stood out to us as the most consistent performers were Google Ad Manager or AdX, Magnite, and Pubmatic.

Several attributes define a good SSP. When it’s time to choose which to use, unless you are an expert, it is beneficial to see what the professionals say. Publift offers this service to you. However, it is helpful to have a basic knowledge of how it works.

Below are some of the best companies currently offering SSP technology:

Google Ad Manager

Google Ad Manager Homepage

Google Ad Manager (formerly DoubleClick for Publishers), is a comprehensive, Google-hosted ad serving platform that streamlines your ad management.

App Lovin Max

AppLovin Max Homepage

Previously known as MoPub,  a Twitter company providing monetization solutions for app publishers and developers around the globe, this mobile focused SSP has now merged with App Lovin Max. Including all of MoPub’s previous features, such as flexible network mediation, App Lovin Max’s new features include universal creative reporting, ad review banner support, support for native ads, and built-In GDPR consent flow


Xandr Homepage

Previously AppNexus, Xandr is an American multinational technology company operating a cloud-based software platform that aims to enable and optimize programmatic online advertising. They have an open, transparent marketplace and powerful enterprise technology that helps marketers connect and engage consumers on thousands of high-quality websites and apps and CCTV.

Magnite (formerly Rubicon)

Magnite homepage

Previously known as the Rubicon project, Magnite was formed in 2020 when it merged with fellow adtech  platform Telaria in mid-2020. Now one of the largest SSPs in the industry, Magnite also offers a DSP, a Private Marketplace (PMP) and Programmatic Guaranteed (PG).


Pubmatic Homepage

The PubMatic platform empowers independent app developers and publishers to control and maximize their digital advertising businesses. It enables advertisers to drive ROI by reaching and engaging their target audiences in brand-safe, premium environments across ad formats and devices.


Publift Homepage

Publift works with almost all the above companies as well as others. By having many SSPs, your business will be able to get insights from all the platforms to get the best deal. Publift uses Fuse to allow the option of adding header bidding that integrates with tags. Fuse is an all-in-one programmatic advertising solution for publishers, powered by a single piece of code.


Are you able to find the best SSP that ticks all the necessary boxes? Do you know which partner to trust?

Publift helps digital publishers get the most out of the ads on their websites. Publift has helped its clients realize an average 55% uplift in ad revenue since 2015,  through the use of cutting-edge programmatic advertising technology paired with impartial and ethical guidance.

If you’re making more than $2,000 in monthly ad revenue, contact us today to learn more about how Publift can help increase your ad revenue and best optimize the ad space available on your website or app.


Success stories