Top Supply-Side Platforms: Which SSP Will Make You Rich in 2025? Let's Find Out!

Owning ad inventory is like having talent. You can succeed, but only if you play your cards right. For publishers, this means choosing the right SSP and setting it up properly.

If you’re skeptical about programmatic advertising’s earning power, just look at the numbers. In 2023, this market’s value was 049,25 billion. By 2029, it’s likely to reach $116,57 billion. Don’t you want a piece of this cake?

Less talk, more action, then! Let’s explore the depths of the programmatic advertising world and help you choose the best supply-side platform (SSP) for your needs.

What’s a Supply-Side Platform

Simply put, a supply-side platform is a programmatic tool that helps publishers sell their ad inventory to the highest-paying customers.

Before SSPs, publishers had to negotiate directly with advertisers. Now, the whole selling process takes milliseconds.

Why? Because an SSP connects publishers to multiple demand-side platforms (DSPs) and ad exchanges. The buying happens via automated actions, so there’s no need for the direct publisher’s involvement.

Besides convenience, here are some other SSP’s benefits for publishers:

• Higher profits. The real-time bidding (RTB) technology ensures the ad slot goes to the highest-paying auction participant.
• Wider reach. With an SSP’s help, publishers can access more advertisers because the platform connects them to various DSPs and ad exchanges. Reaching thousands of advertisers is no longer a fantasy.
• Increased fill rates. An SSP’s goal is to fill your ad slots. To achieve this, the platform uses complicated algorithms to maximize the probability of selling ad inventory.
• Enormous optimization potential. With SSPs, publishers have control over multiple settings, such as floor prices and ad quality.

Sure, an SSP isn’t the only option for publishers. For example, they can sell their inventory to an ad network and just get the profit. However, this option won’t provide them much control and may not be as cost-efficient as using an SSP. So, if you worry about brand safety and want to ensure the quality of ads appearing on your website or app, an SSP is the better choice. Also, if your goal isn’t just monetizing your ad inventory but doing it wisely — you should consider using an SSP.

Where Do SSPs Fit in the Programmatic Ecosystem?

The programmatic ecosystem consists of several essential parts working together smoothly as a perfectly synced orchestra:

• Publishers (owners of websites, apps, etc.) want to sell their ad inventory for the best price and maximize the fill rate.
• Advertisers (individuals, companies, or ad agencies) wish to buy ad inventory to show their ads to the relevant audience.
• Publishers use the best supply-side platforms (SSPs) to offer available ad slots to advertisers and ad exchanges.
• Advertisers use demand-side platforms (DSPs) to connect to ad exchanges, place their bids, and, hopefully, win the auctions and display their ads.
• Ad exchanges, as you can already guess, perform the auction mechanics. They connect DSPs with SSPs, allowing advertisers to bid on publishers’ ad inventory.

Due to automation, this digital universe operates at high speed, with thousands of open auctions happening every second. Obviously, SSPs play a significant part in programmatic advertising and can provide enormous benefits to publishers.

Are an SSP and an Ad Server the Same?

Since publishers can often see both options in the market, it’s crucial to distinguish between an ad server with SSP functionality and an SSP. The typical ad server manages and serves ads based on preset targeting rules. It ensures correct ads are displayed on the right websites or apps, tracks performance, and creates reports. Often, it’s used for direct deals and static campaigns. This type of ad server doesn’t connect to ad exchanges.

So, traditional ad servers can’t replace SSPs. However, some of them have embedded SSP features.

In this case, publishers can use them to sell their ad inventory to multiple demand sources.

Before we explore different SSP examples, let’s answer the question: what’s better, an SSP or an ad server with SSP features? As usual, it depends on your goals and intentions.

For instance, an SSP is enough if you focus only on programmatic sales and want a specialized tool. However, if a publisher prefers the full range of options, including direct and programmatic sales, they should consider an ad server with SSP functionality. In this case, when a high-revenue direct deal emerges, you can prioritize it and earn more.

It’s apparent that an ad server with SSP functionality provides more opportunities for publishers. Still, you must decide whether you need all its features or if a standalone SSP is enough to meet your needs.

What Are the Top Supply-Side Platforms in 2025?

Now that you know the basics of SSPs and can tell between an SSP and an ad server, let’s start discussing your options. But first, ask yourself: what are you looking for in an SSP? What makes an SSP perfect for your needs? With these answers in mind, analyze the following options.

Google Ad Manager (GAM)

This platform is an example of an ad server with SSP features. It helps publishers monetize their ad inventory and offers significant benefits, such as integration with various Google products (such as Google Analytics).

Google Ad Manager is a full-service platform that offers enormous functionality. In addition to selling ad inventory in open auctions, GAM allows publishers to make direct deals with advertisers. Users can access comprehensive reports and manage their inventory via a single dashboard. Moreover, publishers are permitted to set floor prices to ensure revenue.

These features make GAM a good solution for publishers who want integration with other Google products and an easy-to-use interface.

OpenX

It’s a strong choice for large publishers because this SSP can handle vast amounts of traffic. Another strong side is targeting: OpenX can deliver relevant ads to any target audience. Moreover, it controls ad quality and allows publishers to filter unwanted ads.

Publishers can customize reports, include multiple metrics, and receive insights to maximize their earnings.

Epom Ad Server

This is also the ad server with SSP functionality, so it helps publishers connect with various demand sources. But it’s only the beginning. Epom Ad Server offers many optimization tools. For instance, you can use automated CTR, CR, and eCPM optimization to get more money from each ad slot.

What’s more, Epom guarantees a great user experience, which means fast-loading ads, no disruption, and perfect integration into a publisher’s website. For those willing to experiment, Epom Ad Server provides various ad formats, including not-so-common video ads without a player and animated pop-up banners.

Another feature worth mentioning is customer support. If you have any questions, Epom’s team will answer them quickly. They can also advise you on ad optimization if you need help making the most of the platform.

All things considered, Epom can be one of the best supply-side platforms for publishers of any size and ad networks, especially for those looking for a customizable solution with strong optimization features.

PubMatic

This SSP is cloud-based, omnichannel, and supports multiple ad formats, from CTV to mobile and online video. Also, its strong side is transparency. PubMatic provides more control over data compared, for instance, to GAM.

With this SSP, you can stop worrying (“What’s under the hood?”) because it offers advanced reporting functionality. So you can keep track of every step of your programmatic advertising journey.

So, if transparency and control are your priorities, you may consider this platform. Additionally, PubMatic is a solid option for media companies.

Magnite

This SSP focuses mainly on CTV, OTT, video, and display advertising. Magnite works closely with broadcasters, such as Discovery and Disney.

Another essential feature of this SSP is its global reach. Magnite's vast network of connections helps publishers sell their ad inventory to advertisers all around the globe.

To summarize, Magnite is definitely worth trying if you’re looking for one of the top supply-side platforms for video and CTV monetization.

Sovnr

This SSP has been on the market for 10 years, which makes it an experienced option. It’s a common choice for bloggers, small media companies, and affiliate marketers.

The Sovnr platform is easy to work with, so publishers looking for new ways to monetize through affiliate links and ads can choose it for a simple start.

A helpful feature here is audience insights. With them, publishers can optimize their monetization strategies and achieve more with less effort.

Index Exchange

This SSP was a pioneer in implementing header bidding. This technology allows publishers to offer their ad inventory to demand sources before actually selling it, which may result in more active competition and, hence, higher revenue.

Moreover, Index Exchange has been in the programmatic advertising game for over two decades, so this SSP has collected vast experience.

In summary, this option is a good choice for premium publishers, such as big news websites. One of its strong areas of expertise is CTV, so if that’s your priority, Index Exchange can also be helpful.

Xandr

You may have heard its previous name, AppNexus. In 2021, Microsoft bought this platform, making it a part of the Microsoft ecosystem. So, here’s the first competitive advantage: if you want to leverage this ecosystem, Xandr is a strong option.

Xandr is more than just an SSP — it combines the functionality of an SSP, a DSP, and an ad exchange. Hence, its customers include both publishers and advertisers. Xandr may be especially useful to top-tier advertisers because this platform provides access to the private marketplace and premium deals.

Short Conclusions for Decision-Makers

We’ve analyzed the best supply-side platforms, and you’ve noticed that each offers a specific set of strengths. Before moving further, let’s summarize the key findings:

• Large publishers often choose PubMatic or OpenX platforms. Index Exchange is a good option for those interested in premium deals.
• Mid-sized publishers may find their perfect match in Epom Ad Server, especially if they value optimization features and excellent tech support.
• Small content creators often try out Sovnr but can also benefit from Epom’s functionality.
• Google Ad Manager is a solid option for those focused on the Google ecosystem, and Xandr is for publishers prioritizing the Microsoft ecosystem.
• For publishers focused on CTV and video advertising, Magnite is one of the main options.

Sure, these conclusions are too broad. No single solution fits all companies of a specific size or niche. When choosing among the top supply-side platforms, you should consider many other criteria. We’ll look into that a bit later, but first, let’s answer one intriguing question: are there any free SSP options?

What Are the Best Free Supply-Side Platforms?

If you’ve never tried to monetize your ad inventory through SSPs, it makes sense to start slowly. In this case, the desire to save money before seeing the real value is only natural. Luckily, there’s a way to do it, even though finding 100% free SSPs is challenging.

Usually, all the top supply-side platforms require publishers to pay fees or charge a share of the revenue. Still, there are two main options to use them for free.

Freemium model

The word “freemium” emerged from the combination of the words “free” and “premium.” It means that users can access the platform's basic features for free. However, if they need advanced tools in the future, they will have to upgrade to the paid version.

From this perspective, you can consider Google Ad Manager for small business as one of the best free supply-side platforms. Small publishers can use it for free to taste programmatic ad serving. Still, when their appetite starts growing, and the limited set of features isn’t enough anymore, they can upgrade to Google Ad Manager 360.

Free Trial

This model is the opposite of freemium: instead of giving limited access forever (unless a user wants to change it), the platform provides full access for a limited time. In this case, you can try all the features for free and find out whether this platform fits your needs.

A great example is Epom Ad Server, which offers a 14-day free trial. Two weeks isn’t a very long time, but it’s enough to understand how the platform works, try selling your ad inventory and optimize your performance. If you want to proceed after a trial period, it won’t be like buying a black box — you’ll know what to expect.

Another advantage of the free trial model is customer support. If you have trouble with some of the features, you can ask for help and save time searching for answers yourself.

Even though the choice of the best free supply-side platforms is limited, that doesn’t mean you can’t taste the water before jumping in. Try the freemium version or use the free trial option—in any case, you’ll find out what monetizing your ad inventory is like.

Factors To Consider When Choosing Your SSP

You want your SSP to be the best of the top supply-side platforms available. To ensure this, analyze the following criteria.

1. Content. Ask yourself: how many impressions does my website generate monthly? What type of content is there? Where does traffic come from (geographical location, device types, etc.)?

2. Technical requirements. What ad formats do you want to use? Do you need a platform with header bidding or other advanced features?

3. Quality requirements. How essential is brand safety to you? What ad formats are acceptable? Do you have expectations about advertisers (say, their niche)? How important is the loading speed to you and your visitors?

4. Revenue expectation. How much do you want to earn monthly by selling your ad inventory? How much are you willing to pay in the platform fees?

5. Future plans. How fast would you like to grow? Do you want to enter new markets? Do you plan to try new ad formats and advanced optimization features?

Consider these criteria when evaluating the best supply-side platforms. This will help you find the solution that matches your needs and goals.

Final Thoughts

Choosing the right SSP is like finding a business partner. This decision can influence your future success and define your revenues. That’s why it’s insufficient to go for the most well-known name among the top supply-side platforms. What you really need to do — is keep in mind your priorities, aspirations, and limitations.

The market offers many options, and each has strengths. Some SSPs specialize in premium inventory, while others provide a broad reach. Some of them, like Google Ad Market, allow you to use the basic functions for free, and platforms like Epom Ad Server offer a trial period with a complete set of advanced features.

FAQ

• What’s a supply-side platform?

  A supply-side platform is a programmatic tool that helps publishers sell their ad inventory to the highest-paying customers.

• What's the SSP's part in the programmatic ecosystem?

  An SSP connects publishers to multiple demand-side platforms (DSPs) and ad exchanges. The buying happens via automated actions, and the whole selling process takes milliseconds.

• Are an SSP and an ad server the same?

  The typical ad server manages and serves ads based on preset targeting rules. It ensures correct ads are displayed on the right websites or apps, tracks performance, and creates reports. So, traditional ad servers can’t replace SSPs. However, some of them have embedded SSP features. In this case, publishers can use them to sell their ad inventory to multiple demand sources.

• What’s better, an SSP or an ad server with SSP features?

  An ad server with SSP functionality provides more opportunities for publishers. Still, you must decide whether you need all its features or if a standalone SSP is enough to meet your needs.

• What are the top supply-side platforms in 2025?

  Large publishers often choose PubMatic or OpenX platforms. Index Exchange is a good option for those interested in premium deals. Mid-sized publishers may find their perfect match in Epom Ad Server, especially if they value optimization features and excellent tech support. Small content creators often try out Sovnr but can also benefit from Epom’s functionality.

• Are there any free SSP options?

  Even though the choice of the best free supply-side platforms is limited, that doesn’t mean you can’t taste the water before jumping in. There are two main options to get free access to SSPs: the freemium version or the free trial option. The first one means that the platform offers basic features for free with an optional upgrade to the paid version. The second one refers to providing temporary access to the full functionality.