What Is a Supply-Side Platform (SSP)? Definition, Features, Companies, and Examples

A supply-side platform (SSP) is defined as a tool used to coordinate the supply and distribution of ad inventory to and from advertisers. It is used by publishers and digital-out-of-home (DOOH) media owners to optimize inventory usage so that no space is wasted and views for each are maximized.
Digital ads comprise nearly half of the world’s total advertising spends and much of this depends on supply-side platforms. This article will get you familiar with what a supply-side platform is, the best SSP providers to consider, and future trends in this space.
Global digital advertising spends are expected to cross USD 333 billion in 2019, according to eMarketer’s Digital Ad Spending 2019 report. This means, for the first time ever, advertising technology investments are inching closer to non-digital advertising media. And a large portion of this depends on supply-side platforms (SSPs). SSPs are responsible for mediating the allocation of ad content on publishing space. So, does it work? And how can you benefit from the many supply-side platform companies out there? Let’s find out.


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What Is a Supply-Side Platform?

A supply-side platform (also known as a sell-side platform) is a type of advertising technology (adtech)Opens a new window that helps publishers optimize their ad inventory. An SSP is a tool or software that holds publisher’s ad space information and enables them to sell various ad types, including display, video, native, digital-out-of-home (DOOH)Opens a new window , etc.

Traditionally, web publishers would use manual means to assign an ad to each space. But with the rising number of digital marketers and large audiences competing for ad space, this has become unviable in the last decade. That’s where supply-side platforms come in. Working together with and on a similar technology as demand-side platformsOpens a new window (DSP), they take stock of a publisher’s total inventory, evaluate the advertisers and content available, and recommend the best match for every space.

For example, a publisher like Google has an ad space that’s coveted by multiple advertisers. Its supply-side platform will tell the ad exchangeOpens a new window that the space is available and wait for the different demand-side platforms to send their bid. Specifically, Google waits for approximately 120 milliseconds to confirm the selected bid. Based on the bid price, the space is allotted to the advertiser and the content is immediately published.

So, how do supply-side platforms work?

Supply-side platforms evaluate advertisers, set the bidding range, and place the content in real-time. This happens through several micro-transactions across the digital advertising supply chain:

Pro Tip: A typical supply-side platform works on a waterfall model – it checks each bid until it arrives at the perfect fit, passing from one to the next.

Learn More: What Is Programmatic Advertising? Definition, Types, Channel, and AdvantagesOpens a new window


Why Do You Need a Supply-Side Platform?

A supply-side platform performs a critical function for digital advertisers and publishers. Without it, publishers would be limited to a small set of advertisers as it isn’t possible to evaluate so many bids without automation. Plus, there are other challenges of not using an SSP:

From the introduction of real-time bidding in the late 2000s to the rapid evolution of programmatic ads, and now to intelligent ad targeting – SSP technology has come a long way. Let us now look at some of the key features of a supply-side platform.

The 4 Key Features of Supply-Side Platforms

Representation of the 4 Key Features of Supply-Side Platforms

The ad exchange is a highly fluctuating space, with parameters such as audience views, ad space demand, engagement levels, and so on, constantly changing. This makes it critical to be aware of what a supply-side platform is and how it selects an ad to be displayed on a specific ad inventory. Essentially, the process depends on the following features of a supply-side platform:

1. Target geographic selection: An SSP allows publishers to manage their ad slots as per the needs of specific localized audiences and advertisers. For example, an article on the publisher’s site can be read across a variety of cities and countries.Using an SSP, the publisher can ensure that different vendors in different countries have access to the same ad space. This boosts profits from a single space by a significant margin.

2. Real-time ad transactions: Compatibility for real-time bidding (RTB) is possibly the most important feature of a supply-side platform. For example, advertisers can use their DSP to bid for an ad space on a popular article or video. The SSP defines the bid range, the DSP automatically offers a price that’s mutually beneficial, and the SSP looks at the available bids to select the best ad – all in real-time. The SSP may choose to do one of the following for the article or video at hand:

  • If all the prices are too low and there is no winning advertiser, the slot will be kept vacant
  • After going through several bids, the highest one is selected
  • It negotiates with that advertiser to get the desired ad, but at a lower price

3. Bidding for the best ad space: Despite so many entities competing for space, there’s often a mismatch between requirements and availability. For example, an article which has historically proven to enjoy a lot of engagement may have a high bidding range. But for a particular session, there is no bid available in that range.In such a scenario, the SSP will modify the parameters so that there is minimal possibility of the inventory going unutilized. The supply-side platform will leverage historic data from the advertiser (such as average bids) to fine-tune parameters accordingly.

4. Network optimization: Every ad networkOpens a new window comes with its own latency level – latency refers to the time it takes for data to reach its destination. High latency will lead to a slow ad load, and consequently, a poor user experience for the ad consumer. For example, if a space is assigned to a video ad from a high latency network, the ad will take a long time to load, and the consumer might close the ad. TheSSPfunctions as a network optimizer by choosing the best latency level possible for the publisher.

Learn More: Ad Network vs. Ad Exchange: Key Differences and SimilaritiesOpens a new window


The Benefits of Using Supply-Side Platforms

The above list of supply-side platform features also imply the many benefits to publishers. Let’s look at the advantages of an SSP in detail:

1. Increase your ad fill rates

This is the first and most obvious benefit of using a supply-side platform. A website’s fill rate is indicated by the number of ad spaces on a publisher’s inventory and whether they are filled or vacant. Fill rates are directly linked to revenues, as the profit generation process begins only when a customer views an ad or clicks on a CTA.

Supply-side platforms ensure the available ad spaces are sold to the highest bidder, bringing in more revenue per space. It also encourages participation from more advertisers, so that each instance of space-filling is perfectly optimized.

2. Choose the best (not necessarily the highest) price

SSP technology isn’t meant to make the most money out of a space in the short term. A supply-side platform institutes checks and balances so that bids which aren’t relevant are rejected. In the long term, this feature of supply-side platforms raises the overall market reputation and inventory value of the publisher’s website.

For example, if the same ad continues to be displayed in the same space, and consumed by the same audience, impressions will start to drop, and fatigue will set in. There could be an advertiser from a completely different geographic region, with content not relevant to the publisher’s marketing strategies, who is willing to make a high bid. The SSP wouldn’t choose this as it’s irrelevant.

3. Expand your ad reach

Often, publishers would give out ad spaces at throwaway prices simply to fill the inventory. A supply-side platform prevents this by defining a floor price – a minimum price below which no bids are accepted.

Also, the floor price can be negotiated if an advertiser provides distinctively attractive content. The SSP offers a new price point, expanding ad reach, as fresh content will help engage new audiences who haven’t interacted with the website before. Again, this drives the publisher’s inventory value in the long run.

4. Limit impression frequency

In today’s crowded digital marketplace, it is likely that a customer will see the same ad content repeatedly. This will significantly bring down the impact of impressions, as the consumer is likely to avoid any further content from that advertiser.

A supply-side platform collaborates DSPs to define an ad frequency cap, limiting the number of similar impressions. Some publishers may even ask the consumer if they found an ad relevant, feeding this data into the SSP for better targeting, next time around.

Given these compelling benefits of SSP, ad-tech providers across the world are eager to innovate and deliver better outcomes via new and emerging technologies. If you are looking to choose from the best supply-side platforms, let’s talk about the platforms available.

Learn More: Top 5 Programmatic Advertising Platforms for 2020 and BeyondOpens a new window

The 4 Top Supply-Side Platforms

Representation of the 4 Top Supply-Side Platforms

While the definition of supply-side platforms may be extremely clear and specific, most providers have a wider service portfolio spanning SSPs as well as ad exchanges and reporting facilities. This allows for easier integration and ready access to an expansive demand-side network.

Here is a quick checklist of the best supply-side platforms you could consider.

1. Google Ad Manager

Google’s Ad Manager includes several component services such as its ad server – Google DFP, and ad exchange – Google AdX. Together, they allow publishers to switch between different ad networks and sell their inventory in real time. Google’s Ad Manager offers built-in support for video, customized ads, and native advertising – however, you may need to meet certain eligibility criteria to leverage Google SSP technology.

2. OpenX

OpenX ranks high on any list of supply-side platform companies, and with good reason. It boasts a powerful solution that goes above and beyond pure-play SSP. There is an ad exchange, a real-time bidder, mobile app monetization solution, as well as audience reports via OpenX’s proprietary technology. There’s also support for private marketplaces and premium inventory, making OpexX popular among high-value publishers.

3. AppNexus

AppNexus is another popular contender on any list of SSPs. It’s similar to OpenX, but boasts transparency as its primary selling point. AppNexus comes with header-bidding support (more on that later) and has worked with leading publishers, including Microsoft. Like most large SSP companies, AppNexus comes with its own ad exchange called the AppNexus marketplace (but isn’t limited to this community).

4. Rubicon Project

Rubicon was inspired by the necessities of the digital era, with advertising technology for both publishers as well as advertisers. It is among the most recognized SSPs out there, used across one million websites and 60,000 apps. From global giants such as Conde Nast, and The Wall Street Journal, to digital disruptors – Spotify and SoundCloud, some of the world’s best digital real estate is managed by Rubicon. Its unique selling proposition is probably a high degree of customization, in addition to real-time bidding support.

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Given the powerful features offered by all these providers, how do you make the right call when selecting a vendor? Here is an easy guide for you to follow.

How to Choose the Best Supply-Side Platform?


Ask yourself the following questions when reviewing SSP options.

1. Is the provider’s ad-server ready to integrate with new demand platforms?

It is the job of a supply-side platform to connect with the largest possible advertiser base, but rapid onboarding of new demand channels will make it most efficient and sustainable.

2. Does the platform include brand safety?

Publishers will often have specific rulebooks and parameters to protect their brand. The selected SSP must be in-sync with this – for example, Rubicon Project claims that it has blocked 20 billion bad ads and 420 billion threats to improve ad experiences.

Learn More: What Is Display Advertising? Definition, Targeting Process, Management, Network, Types, and ExamplesOpens a new window

What is the Future of Supply-Side Platforms?

We expect existing SSP software to be heavily impacted by next-gen technologies including AI and Blockchain. This will also bring in more efficient capabilities like header bidding, expanding ad reach like never before.

The future of SSP will be shaped by the four following trends:

Despite being around for over a decade now, supply-side platforms continue to be an exciting and rapidly evolving landscape. They are now a must-have for any publisher’s toolkit and the foundation for breakthrough new ideas such as AI-based programmatic ads.

Are you leveraging a supply-side platform? Tell us about your experience and recommendations on TwitterOpens a new window , FacebookOpens a new window , and LinkedInOpens a new window We’d love to hear from you