What on Earth is Prebid? What Publishers Need to Know

Prebid revolutionized the programmatic advertising industry when it burst onto the scene in 2015.

Still today, it remains the go-to header bidding solution for millions of publishers worldwide.

But what is it exactly and how does it work? That’s what we’ll explain in this article.

What is Prebid?

Prebid is an open-source suite of programmatic advertising technologies that empower publishers like you to efficiently maximize revenue through header bidding.

With header bidding, multiple advertisers can bid on your ad inventory simultaneously in real time, leveraging greater competition and increasing your revenue.

There are four different components of Prebid:

  • Prebid.js
  • Prebid server
  • Prebid mobile
  • Prebid video


Prebid.js, also known as a Prebid wrapper, is a free, open-source JavaScript library (hence the “.js”) that conducts auctions between various demand sources simultaneously.

The library operates directly in the user’s browser and manages the auction for ad slots in real-time, prior to making a call to the publisher’s ad server. It supports a wide range of ad units, demand partners, and features, making it a flexible and comprehensive solution.

Prebid.js is Prebid’s client-side heading bidding solution.

Prebid Server

Prebid Server is a server-side header bidding solution that conducts the auctions on a server, reducing the load on the user’s device and potentially decreasing latency.

You can read more here on the difference between client-side and server-side header bidding.

Prebid Mobile

Prebid Mobile is designed to bring the benefits of header bidding to the mobile app environment. It’s an SDK (Software Development Kit) that app developers can integrate directly into their iOS and Android apps.

Like the other Prebid offerings, Prebid Mobile conducts an auction among multiple demand partners before the ad server’s call, increasing competition and ad revenue.

Prebid Video

Prebid Video offers header bidding solutions specifically for video content. Prebid Video supports instream and outstream video ad units, allowing you to maximize their video ad revenue.

How Does Prebid Work?

Here’s how it works, step by step:

  1. User visits website: The process begins when a user visits a webpage or opens an app where Prebid is implemented.
  2. Bid request is initiated: Prebid.js, Prebid Server, Prebid Mobile, or Prebid Video (depending on your setup) sends out bid requests to all participating demand partners. These requests contain vital information such as the size of the ad, the location of the user, and details about the site or app.
  3. Demand partners respond: Each demand partner evaluates the bid request and decides whether and how much to bid for the ad impression. This decision is based on the demand partner’s algorithms, which consider factors such as the user’s profile, the context of the site or app, and the current demand for ad space.
  4. Bids are returned: The demand partners send their bids back to Prebid. Each bid represents a promise to deliver a specific ad at a specific price if the bid wins the auction.
  5. Auction is conducted: Prebid collects all the bids, and an auction is conducted. The highest bidder wins the auction.
  6. Winning bid sent is sent to ad sever: Prebid then sends the winning bid to the ad server. This process happens very quickly.
  7. Ad server makes a decision: The ad server then compares the winning bid from Prebid with other line items (such as direct deals and guaranteed contracts). If the Prebid bid is the highest, the ad server instructs Prebid to deliver the winning ad.
  8. Ad is displayed: Finally, the winning ad is served to the user’s device, whether it’s a display, video, or native ad.

There are a lot of steps, but it’s important to remember that everything occurs within a matter of milliseconds!

Benefits of Prebid

  1. Increased revenue
  2. Transparency
  3. Reduced latency
  4. Flexibility and compatibility
  5. Community support
  6. Greater control
  7. Improved reporting and analytics

Benefits of Prebid

Increased Revenue

The increased competition facilitated by Prebid’s header bidding results in higher bid prices, leading to improved revenue.

Open Source and Transparent

Prebid is completely open source, which means its code is freely available for anyone to view, use, modify, and distribute. This provides unparalleled transparency into the auction process, giving you complete control and visibility over how your inventory is sold.

Reduced Latency

Prebid.js operates directly in the user’s browser, and Prebid Server conducts auctions server-side, both designed to reduce latency and ensure a better user experience.

This can lead to improved page speed compared to traditional waterfall models, keeping users engaged with the content while the bidding process occurs in the background.

Flexibility and Compatibility

Prebid is compatible with all major ad servers and a vast array of demand partners. It supports multiple ad formats, including display, video, and native ads, across desktop and mobile platforms.

This makes it a highly versatile tool that can fit into virtually any publisher’s monetization strategy.

Community Support

As an open-source project, Prebid is backed by a robust community of developers and digital advertising professionals. They continually contribute to its development, keeping it updated with the latest features and improvements.

This community also provides extensive documentation and support resources, making it easier for you to implement and troubleshoot the technology.

Greater Control

With Prebid, you can customize settings according to their needs, such as setting price floors, selecting which demand partners to include in the auction, and controlling how long the auction lasts. This level of control is a key advantage of Prebid, as it enables you to tailor the technology to your unique objectives and constraints.

Improved Reporting and Analytics

Prebid also offers comprehensive reporting features, helping you track your performance, identify trends, and make data-driven decisions to optimize ad revenue.

How to Implement Prebid

Implementing Prebid involves a sequence of steps, each vital for ensuring the platform functions as intended.

While the precise steps can vary depending on your specific setup and requirements, the general process is as follows:

  1. Choose Your Prebid Product

Depending on your needs, you might choose Prebid.js for a website, Prebid Mobile for a mobile app, or Prebid Server for server-side header bidding. For video content, you can use Prebid Video.

  1. Download and Install

Download the appropriate Prebid library from the Prebid.org website. For Prebid.js, the file should be hosted on your server or a Content Delivery Network (CDN) and then included in the header of your webpages.

  1. Define Ad Units

Next, define your ad units within the Prebid script. You’ll need to specify the sizes of the ads and the bidders for each unit. This information is critical for demand partners to make their bids.

  1. Configure Demand Partners

Add your selected demand partners. Each partner might require additional parameters, like placement IDs or keys, which you’ll need to add.

  1. Set Up Your Ad Server

Prebid works alongside your ad server, which needs to be set up with line items corresponding to the different price levels your bids might fall into.

The ad server will make the final decision on which ad to serve based on the winning bid from Prebid and any other line items in the ad server.

  1. Enable User Syncs

User syncing allows demand partners to match users and serve more targeted ads, which can potentially increase your revenue. Prebid offers several ways to manage user syncing to balance revenue potential with user experience.

  1. Test Your Setup

After setting up, test thoroughly to ensure everything is functioning as expected. Check if bid requests are being sent and received properly, if the auctions are running correctly, and if the winning bid information is properly passed to the ad server.

  1. Optimize

Once live, monitor your performance and continually optimize your setup. You may want to adjust settings such as price granularity, timeout settings, or your roster of demand partners to improve performance.

Remember, implementation may require technical expertise, especially if you have custom requirements.

Prebid.org provides extensive documentation and a supportive community to assist with the implementation process. However, if your team lacks the necessary expertise, you might consider seeking help from a certified ad management company like Adnimation.

Hybrid Header Bidding

The question of whether to use the Prebid.js wrapper (client-side header bidding) or the Prebid Server (server-to-server header bidding) is a question that all publishers grapple with.

Some prefer the benefits that client-side has to offer, while others prefer server-to-server.

And true, they both have their pros…and cons.

That’s why we developed an innovative hybrid header bidding solution, which allows our partnering publishers to utilize both Prebid.js and Prebid Server to combine the advantages of both methods.

In fact, hybrid header bidding has been shown to outperform standard header bidding by an average of 18%.

To learn more and see how you can get started, please contact us today.

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