The best supply-side platforms (SSPs) for publishers in 2021

SSP featured image

There are many ways to monetize your website content. Using the optimal mix of programmatic deal types is one method. Today, we’re going to be talking about supply-side platforms (SSPs). Also known as seller-side platforms.

By working with SSPs, you’re able to unlock incremental revenue potential. They’re used to connect publishers with multiple ad networks, exchanges, and demand-side platforms (DSPs) simultaneously, with the potential of better yield, improved fill rate, and unified revenue reporting.

Sounds great! But you might be asking yourself, what’s the catch?

Well, there are many SSPs for publishers to choose from. Also, as they offer similar features, it can be hard to differentiate them. That’s why we’ve selected 9 SSPs for you to review and highlighted what makes them special.

However, at the end of the day, only you know what technology works best for your needs. So we’ve also included a few tips on how to choose the best SSP for your website(s).

But first, let’s first start with the basics.

What is an SSP?

Like most publishers, you probably started monetizing with AdSense at the beginning of your journey. When you use AdSense, you’re sending bid requests to one demand partner, Google.

With SSPs, publishers can send bid requests to multiple demand partners using a single platform. These include ad networks, exchanges, and DSPs that the SSP is connected to.

A visual explainer on what a supply-side platform (SSP) looks like
A visual example of how publishers can connect to different Ad Ops stakeholders via an SSP

Why would you want to work with an SSP? Well in one move, you’ve diversified your revenue channels by opening up the inventory to more buyers. Therefore, increasing your chances of achieving a better fill rate and overall yield.

They also help with analyzing and sharing your audience insights. For instance, demographics like their age and gender. Or psychographics like their interests. In a previous guide on activating first-party data, we talked about making your inventory more valuable by showcasing your audience insights to advertisers.

What is a DSP?

The complete opposite of an SSP.

Publishers use SSPs to access more buyers. Similarly, advertisers use DSPs to access more sellers (like yourself). They’re used to buy ads from various ad exchanges at scale.

Let’s use an example by comparing the process to the stock exchange. Instead of buying and selling ad inventory, we’re buying and selling company shares.

  1. Your company (website) has shares (ad inventory) that they can sell.
  2. Your buyers (advertisers) want to buy shares from companies similar to yourself.
  3. To reach the widest range of potential buyers on the stock (ad) exchange, you enlist the help of a broker (SSP).
  4. Similarly, your buyers also use a broker (DSP) to access shares they wouldn’t necessarily get on their own.

These are just two technologies that are meant to maximize revenue for both advertisers and publishers.

How do SSPs work?

We know that SSPs communicate with DSPs to select the highest bidder interested in reaching your audience.

But how exactly does this process work?

  1. After selecting which SSP(s) you want to work with, you make your inventory available through them.
  2. A user lands on your website.
  3. An ad request is made to multiple ad exchanges and DSPs through your SSP, along with the Deal ID.
  4. The SSP looks for all relevant buyers or deals that will match your inventory.
  5. In the open auction, DSPs bid on your ad unit with the price and creative to be delivered.
  6. Your SSP determines a match by looking at the advertiser’s audience requirements, the highest bid price, and your ad unit configuration settings.
  7. A winner is decided by the ad server.
  8. The winning bid is sent to your website and displayed to your website visitor.
A visual explainer on how supply-side platforms (SSPs) works
A visual example of how SSPs work

9 best supply-side platforms

Choosing which SSP makes the most sense for you can be tricky as they generally have similar product offerings.

Let’s focus on what makes them stand out.

Index Exchange

Available ad formats: mobile, video, native
Deal types: direct and PMP

As noted in their name, IX is an ad exchange that offers its SSP services to publishers. Services that go past their available ad formats and deal types.

For instance, publishers who manually review their content for malvertising know that process is time-consuming. IX gives you the ability to automate this process based on your requirements. Know specific industries or creative types that shouldn’t show up next to your content? Block them.

If you read our last guide on first-party data monetization strategies, you may recall that we talked about Data Management Platforms (DMPs). For those using DMPs, IX offers server-side integrations with specific partners for select publishers on user segmentation and audience targeting.


Available ad formats: mobile, video, native
Deal types: direct and PMP

Like IX, OpenX is also an ad exchange that offers SSP services.

They specifically offer OpenAudience, which gives publishers the ability to gain audience insights and learn more about their own users. Insights that can help create custom audiences with demographic, first-party, and third-party data segments.


Available ad formats: mobile, video, native
Deal types: direct and PMP

Rubicon Project and Telaria finalized their merger in April 2020 to create their own SSP. They rebranded themselves to become Magnite. Since then, Magnite has gone on to acquire SpotX to expand its services into the video advertising space. Enabling them to offer a Connected TV (CTV) platform.

For publishers who heavily rely on video advertising, this may be an interesting opportunity for you to explore.


Available ad formats: mobile, video, native
Deal types: direct and PMP

On top of being a Google Open Bidding partner, Sovrn also offers email and commerce monetization amongst its advertising products. You can either directly or indirectly monetize your hashed emails with Sovrn. And if you’re involved with affiliate marketing, you can benefit from their commerce monetization option.


Available ad formats: mobile, video, native
Deal types: direct and PMP

TripleLift now offers a beta CTV platform for publishers working with video advertising. They are also an ad server that allows publishers to power their direct native deals.

If you tend to use native display advertising more than other formats, you might be interested in Dynamic Templating. It adjusts an advertiser’s creative to create native ads that match your content layout in real-time.


Available ad formats: mobile, video, native
Deal types: direct and PMP

In June 2018, AppNexus was acquired by AT&T and rebranded as Xandr. AppNexus’ SSP product was rebranded as Xandr Monetize. More recently, in December 2021, Xandr was acquired by Microsoft.

Like most SSPs, Xandr offers a header bidding wrapper with access to premium demand. They are also venturing into TV advertising to help capture Over-The-Top (OTT) demand.

Xandr also works as an ad server to help publishers optimize their inventory and maximize their yield.


Available ad formats: mobile, video
Deal types: not known

While they do support desktop, mobile, and video ad formats, they also offer ad quality control and compliance. ConnectAd takes the manual effort of reviewing your website for bad ads off of your hands.

This gives you more time to work on other aspects of your business, or website monetization goals.

Improve Digital

Available ad formats: mobile, video, native
Deal types: direct

Improve Digital’s main solution, 360 Polaris, includes the Classic SSP. Here, you can manage your direct deals (not including PMP deals). You can use video, native, rich media, display ad formats across devices like TV, mobile, tablet, and desktop.

Smart AdServer

Available ad formats: mobile, video, native
Deal types: direct and PMP

As noted from its name, Smart AdServer is an ad server that’s integrated with an SSP. Similar to ConnectAd, they also offer ad quality and brand safety checks. With unified reporting, preset auction packages, and curated deals, publishers can reach new buyers with minimal effort on their end.

How do you choose the best supply-side platform?

As you can see, there are many SSPs for you to choose from. And as you’ve learned, they’re great for diversifying the number of buyers to bid on your inventory.

However, just before you go out and start partnering up with every single SSP known to publishers, you need to think about your site speed. Generally, an SSP will give you a piece of code to add to your website to add the partners they’re associated with. More code may slow down your site.

Also, it’s not guaranteed that your fill and win rates will exponentially go up just by adding more SSPs to your ad tech stack.

So, how do you know who’s right for you?

Start by asking yourself the following questions when researching SSPs:

  • What analytics and reporting do they offer?
  • How customizable is their reporting for my needs?
  • What demand partners are they working with?
  • Can I easily integrate their technology with different ad exchanges or existing demand relationships?
  • What can I control – price flooring, inventory and campaign management, etc.?
  • How reliable is their support (documentation vs timely customer service)?
  • How simple is the setup?

As with anything in ad tech, always test different SSPs to compare their performance. What works for some, may not work for all.

In summary

SSPs are a great way for publishers to uncover new revenue by reaching a wide variety of advertisers. They work as your intermediary to access ad exchanges, ad networks, and DSPs.

We have discussed a few examples of SSPs. However, at the end of the day, it comes down to selecting the partner(s) that make the most sense for your needs. Once you’ve selected your SSP(s), ensure that you’re testing and monitoring their performance.

Which demand partners are participating and winning during the auction? Are they providing incremental lift?

Through these tests, you will be able to maximize your revenue potential.

While you're here...

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