What Is a Supply-Side Platform: Importance and How to Create a Great One

The programmatic advertising ecosystem can often feel like a labyrinth, and it’s easy to see why. Between ad exchanges, networks, DSPs, DMPs, and countless other acronyms, publishers frequently find themselves stuck among intermediaries, struggling to sell their ad inventory at its true value. The complexity can slow things down, dilute revenues, and take control away from the publishers.

But what if there was a way to simplify the process, cutting through the middlemen and giving publishers more control over their ad sales while maximizing revenue?

Good news: that’s exactly what an SSP, supply-side platform, is designed to do: allow publishers to sell their ad space in real time, either through ad exchanges or, what’s even better, by connecting directly with demand-side platforms (DSPs).

The importance of SSPs becomes clear when you consider that, as we noticed in our dive into demand-side platforms, if you’re building a DSP from scratch, having your own SSP is a must. But if you’ve already got an SSP up and running, creating your own DSP isn’t really needed.

Why is that, how do they work, and why are they such a key piece of the programmatic ad puzzle? Let’s break it down and explore the real value they bring.

What is a supply-side platform?

At its core, an SSP is a technological platform that enables owners of websites, apps, and other online media to manage their advertising space inventory, fill it with ads, and receive revenue through automated auctions. This happens on an impression-by-impression basis for display, video, and native ads, ensuring that every ad placement is sold to the highest-paying advertiser.

We won’t dive into specific supply-side platform examples here, primarily because many publishers often partner with multiple SSPs, as each one may bring its own unique connections to agencies and DSPs, often representing different markets, deal types, and even geographic specialties that help publishers reach buyers targeting specific regions.

And secondly, larger publishers may prefer building custom solutions tailored to their specific needs. This gives them more control over their inventory and revenue while accounting for all the unique features they require.

What we’ll focus on in more detail are the facts that help SSPs become the major strategic asset for any publisher.

Fact 1. Real-time bidding power

SSPs rely on real-time bidding (RTB), allowing advertisers to bid on individual ad impressions as they happen. These auctions occur in milliseconds, and the highest bidder wins the spot. This process ensures that a publisher gets the best possible price for every impression, with SSPs running millions of these auctions per second.

Fact 2. Flexible programmatic advertising techniques

Most SSPs often use header bidding, a popular method where multiple advertisers can bid on ad space simultaneously, however, SSPs can also operate through alternative methods:

• Waterfall method: where SSPs prioritize demand sources one by one, passing opportunities sequentially.
• RTB without header bidding: SSPs can run auctions directly with demand-side platforms (DSPs) or ad exchanges using the SSP’s auction process.
• Server-side header bidding: here, the auction happens on the server, not the user’s browser, reducing latency.
• Direct deals & programmatic guaranteed: SSPs also support exclusive deals and guaranteed sales for a more controlled buying process.

Each of these methods can offer flexibility depending on specific monetization goals.

Fact 3. Turning information into effective action

While selling ad space is at the heart of what SSPs do, the best platforms offer a range of features that let SSPs do much more than simply auction off ad space: from budgeting and frequency capping to ad targeting and real-time reporting. They allow publishers to monitor performance, optimize campaigns, and even uncover growth opportunities.

SSPs analyze user data to prioritize ads based on real-time demand, past performance, and user behavior, driving optimal results for both publishers and advertisers.

Fact 4. Access to a vast network of advertisers

One of the standout features of an advertising supply-side platform is its’ ability to connect publishers to a large ecosystem of demand sources. Instead of relying on a single buyer or ad network, SSPs plug publishers into DSPs, ad networks, agencies, and more. This ensures that every impression is seen by a wide range of potential advertisers, maximizing revenue potential.

Fact 5. Direct connections with the demand side

SSPs don’t just stop at ad exchanges (marketplaces where buyers and sellers meet). Some advanced SSPs can connect directly with DSPs, cutting out intermediaries and creating a more transparent and efficient process. This direct integration often leads to higher revenue for publishers by reducing the number of middlemen involved and lowering costs for advertisers, making it a win-win for everyone.

Additionally, SSPs can integrate with private marketplaces (PMPs), ad networks, and agency trading desks (ATDs), giving  even more options to reach premium advertisers through direct deals. This flexibility helps publishers tap into high-quality, controlled demand for their inventory.

Fact 6. Benefiting everyone, from big to small publishers

SSPs aren’t just for large-scale publishers with massive traffic; they offer value across the board. For big publishers, SSPs provide smarter selling tools and an additional revenue stream by offering SSP services to smaller, less tech-savvy publishers — taking a commission in the process. This opens up new business opportunities by allowing large publishers to help others monetize their traffic while simultaneously boosting their own ad revenue.

For smaller publishers, SSPs are a gateway to premium demand that would otherwise be out of reach. By tapping into the expertise and infrastructure of larger players, smaller publishers can access top-tier advertisers and unlock better monetization opportunities.

How does an SSP work?

To make the supply-side platform meaning easier to grasp, imagine a publisher as the owner of a bustling hotel, with each room representing a valuable asset, just like an ad space on a website. In this scenario, the supply-side platform steps in to serve as the concierge, responsible for managing the occupancy and revenue of each room.

Step 1: Inventory is the room list

First, the concierge gathers all the rooms in the hotel — the ad inventory. They take note of which rooms have a great view (premium ad spots), which ones are smaller but cozy (lower-tier inventory), and categorize everything. This detailed room list is key to attracting the right guests, or in this case, advertisers.

Step 2: The auction house

Now imagine a publisher has a dynamic auction running for each room. The SSP takes the room list to an open marketplace, much like placing the rooms on a hotel booking site. Advertisers (guests) see the rooms and start bidding in real-time for the right to place their ads in these spaces. The highest bidder gets the keys to the room, or the ad slot, right away. Everything is fast, transparent, and automated.

Step 3: Connecting multiple marketplaces for more bids

To ramp up competition and ensure the publisher is getting the best deal for every room, the SSP doesn’t just list the rooms on one marketplace — it connects to multiple platforms. Think of it as being listed on all major booking websites, driving up demand. More guests (advertisers) bidding on the rooms creates  fierce competition, driving up the price. It’s not just about selling the room; it’s about selling it to the highest bidder.

Step 4: Optimizing for maximum value

Finally, the hotel manager (publisher), is still in control. He decides the minimum price he’s willing to accept for each room, whether to accept only certain types of guests (ad filters), or even negotiate private, direct deals with premium clients.

The power of SSPs for publishers

Earlier in this article, we examined the concept of supply-side platforms in general and highlighted their overarching benefits. Now, let’s turn our attention to the distinct advantages SSPs provide.

1. Automation of ad inventory sales

SSPs streamline the process of selling ad inventory by automating transactions between publishers and advertisers. This eliminates the need for manual negotiations, allowing publishers to focus on other aspects of their business, confident that their ad space is being sold optimally and quickly.

2. Yield optimization

SSPs are designed to maximize revenue for publishers through intelligent bidding and auction mechanisms. By leveraging advanced algorithms, an SSP can automatically adjust ad placements and rates based on factors like audience behavior, content type, time of day and more.

On top of that, a good SSP reduces interactions with ad exchanges and minimizes their number, or connects publishers with DSPs directly, leading to more efficient and transparent operations. The key advantage here is that the platform doesn’t resell the inventory multiple times, ensuring everyone’s revenue isn’t reduced. Additionally, it enables faster ad loading, providing a better user experience where ads appear almost instantly.

3. More control

Custom supply-side platforms place publishers firmly in the driver’s seat when managing their ad inventory and auction strategies, empowering them to exert greater control over which ads are displayed and how they fit the needs and preferences of their audience.

• Auction rule customization: Publishers can set key parameters for auctions, such as minimum bids, priority levels for certain advertisers, and filters to block undesirable content. This ensures that the ads displayed match the publisher’s quality standards and audience preferences, even in an automated environment.
• Inventory optimization: SSPs offer sophisticated algorithms that optimize ad placements based on audience segmentation, content, and timing. This allows publishers to maximize engagement and revenue by showing the right ad at the right time.
• Selective access to inventory: Publishers can control which DSPs and advertisers are allowed to bid on their inventory. By limiting access to high-quality advertisers, they can protect their brand integrity while still benefiting from automated auctions.
• Ad verification: SSPs can integrate with third-party verification tools that scan and audit traffic for legitimacy. These solutions analyze ad viewability, fraud, brand safety, and invalid traffic across inventory.
• Bot detection and prevention: One of the largest threats to traffic quality is bots or non-human traffic. Bots can drive fake impressions and clicks, which waste advertisers’ budgets and artificially inflate publisher revenues. Advanced SSPs use anti-bot solutions to minimize this issue.
• AI-driven fraud detection: AI algorithms offer immense value by recognizing traffic anomalies and suspicious patterns at scale. Through behavioral analysis, they can monitor key metrics like unusual click-through rates or engagement behaviors, allowing for the timely identification of fraudulent activity. This proactive approach helps SSPs maintain trust, optimize performance, and protect against revenue loss.

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Ensuring you select the highest-performing SSP strategy

While some publishers choose to work with multiple SSPs at once — a solid strategy, as we’ve mentioned before — Oxagile offers solutions to streamline the integration and unified management of these SSPs, like consolidating data into unified dashboards, enhancing cross-SSP performance and more.

We also support our clients in taking the next step in optimizing their supply paths by enabling greater traffic control and cost-effective traffic quality management by building tailored SSP software solutions.

Additionally, we upgrade SSP platforms with tools to ensure privacy law compliance, offer in-depth reporting, expand integrations, improve user interfaces, and implement AI-driven automation. These enhancements lead to better performance, scalability, user experience, and brand safety, all of which contribute to steady revenue growth.

If you are eager to discover more on elevating your ad inventory monetization, good news: we are eager to share our expertise, use cases, and insider knowledge on latest best performing SSP tactics with you right away.