Header Bidding Wrappers – All you need to know

Header bidding, the latest buzzword in the digital advertising industry, has been here for a while though many publishers still struggle to understand the terminologies involved. We have already talked about the basics in our previous blogpost “Project Agora Header Bidding: The Evolution of Header Bidding”. It is time to dig a bit further, and discuss about the header bidding wrappers —an essential part of the process.


What is a Header Bidding Wrapper?

A header bidding wrapper, also known as a container or a framework, is a technology that organizes all buyers and sets the rules for efficient programmatic auctions (e.g., how many bidders will participate on the auction, auction timeout, floor prices). It is a javascript code that resides on the publisher’s webpage and provides a set of key technical and operational benefits that help publishers to run, test and optimize the header bidding process.

How do Wrappers streamline the header bidding process?

Header bidding wrappers exist to streamline the header bidding process and make the overall implementation easier for publishers. Using a wrapper, publishers are able to manage any number of demand partners and set the necessary auction rules (e.g., centralized timeout) without the need to set up auctions individually for each bidder. This eliminates the complexity and the extra code introduced with each new demand partner.

Additionally, wrappers allow you to include services such as tracking, analytics, consent collection and viewability without dealing with unnecessary technical complexities and errors. Last but not least, many wrappers are able to simplify the problem of the line-item creation by translating the header bidding values from each partner into a common parameter for the ad server.

How do Wrappers work exactly?

A header bidding wrapper acts as an asynchronous container triggering the bid requests to all demand partners at the same time and in a timely manner.

How header bidding wrapper helps publishers run and optimize the header bidding process

As shown in the above simplified workflow, the main steps involved in how the wrappers work, are:

      1. User requests the webpage, where the wrapper’s code is included.
      2. Header bidding wrapper triggers bid requests to all integrated demand partners simultaneously.
      3. Demand partners respond with their bids and wrapper determines the winning bid and send it to an ad server (such as Google Ad Manager).

Finally, the Ad server makes its final decision and serves the ad.

Key Header Bidding Wrapper features and benefits

Header bidding wrappers, apart from their primary function to generate bid requests, collect bids, and communicate them to the ad server, they also provide the following key functions and benefits:

  • Revenue uplift. Using header bidding wrappers publishers can easily manage the auction, making the inventory available to more demand partners at the same time, fostering the competition and earning higher CPMs and revenue uplift.
  • Less operational overhead. Instead of having to manage the code for each demand partner individually, like in the case of waterfall, wrappers help publishers to easily add/remove demand partners for the auction, eliminating a lot of tedious setup and maintenance work.
  • Low discrepancy. Header bidding wrappers provide an easier and streamlined header bidding implementation, helping publishers to have close to zero discrepancy and avoid impression leakages from the demand partners within a waterfall monetization stack.
  • Asynchronous auction. Wrapper ensures that all demand partners have their bid requests triggered at the same time, creating this way a unified auction. The asynchronous code keeps the overall ad experience asynchronous, preventing bidders to delay another bidder’s code from loading. Additionally, ads can be loaded in sequence without blocking the rest of the publisher’s webpage content to load, optimizing the user experience.
  • Universal timeout management. To manage how long the browser waits for bidders to respond. This helps reduce latency by enforcing a deadline to the auction and avoid any delays on bid returns.

Learn how Newsauto.gr significantly decreased inventory leakage and discrepancies up to 70% (from 5.7% to 1.7%) using Project Agora’s Header Bidding solution here.

Challenges of Header Bidding Wrappers

Though the advantages of using a wrapper outweigh the downsides, before investing the time and resources to implement one, publishers should know the challenges that may come up on the way:

  • Technical Complexity. Skilled development resources are needed in order to understand wrapper tag technology, configure it and troubleshoot potential issues. Additionally, each wrapper has its own implementation and configuration setup, which means that it would be costly and difficult to repeat the process for every new vendor. This is what makes publishers resistant to wrapper changes.
  • No User Interface. Many header bidding wrappers (e.g., Prebid.js) do not support every user interface, and any configuration needs to be done directly in the wrapper code.
  • Configuration challenges. If the wrapper is not configured properly, it can affect the page load and cause revenue loss.


Most popular Header Bidding Wrappers

There are multiple vendors that offer header bidding wrappers. Some of them use open-source platforms from other vendors to build their own wrappers and others use closed system solutions. Based on their function, header bidding wrappers can be client-side, server-side or hybrid. The most sophisticated publishers don’t just use one type or the other. They are using both earning the benefits from both types. Let’s have a look at the most popular ones:


Prebid.js is one of the most popular open-source client-side wrappers in the ad tech market. It is free to use and has been the foundation for every header bidding strategy since 2018. Prebid.js provides a code set for publishers and developers to set up and run header bidding themselves. While it may be free and easily accessible for everyone, it requires development resources in order to have it integrated properly. It comes with a wide list of demand partners, analytics adapters, and built-in modules to help with important functions and services, such as currency conversion, GDPR and User ID Modules.

Some additional benefits of Prebid.js is the flexible technology, working with multiple formats including display, native and video on both mobile and desktop. Last but not least, Prebid has its own community network providing professional help from experts anytime.

According to some recent figures, around 69.8% of publishers who use client-side header bidding wrappers are using Prebid instead of a proprietary solution.

Header bidding wrapper is a javascript code that organizes all buyers and sets the rules for efficient programmatic auctions.

Source: Kevel Header Bidding 2020 Tracker

Google’s Open Bidding

Open Bidding, also known as Exchange Bidding in Dynamic Allocation (EBDA), is Google’s answer to header bidding. Open Bidding is a server-side wrapper solution available only for Google Ad Manager 360 users. It enables a unified auction where ad exchanges and SSPs can compete along with Google’s Ad Exchange (AdX) for an impression, just like header bidding.

The main differences with Prebid.js is that it is not open source, but has less technical overhead. Open Bidding runs in Google Ad Manager, working with the existing tags on the website, so publishers do not need to install or maintain any complex header codes on their website. The auction takes place on the ad server and not on the user’s browser this way decreasing the page latency and improving the UX experience. One additional benefit is that Google aggregates the payments from all demand partners improving the payment process for the publishers.

On the other hand, Open Bidding is a feature of Google’s ad server and the auction process remains hidden from publishers and the demand sources, other than Google. It allows publishers to add their own demand partners along with AdSense and AdX, but they need to have direct relationships with each demand source they need to activate. One more difference or downside has to do with the number of the bidders available for usage. Open Bidding allows only a limited number of bidders, while in the case of Prebid.js the list of compliant bidders is longer and fast-growing.

Amazon Publisher Solutions

Amazon is not only one of the most popular bidders, it also provides one of the most popular server-side header bidding wrappers, Transparent Ad Marketplace (TAM) and Unified Ad Marketplace (UAM). Both of these solutions work on a server-side model similar to Google Open Bidding, but offered to different users.

The UAM (Unified Ad Marketplace) is a cloud-based marketplace which allows mid-size publishers, who don’t usually have direct SSP relationships, to monetize their websites via Amazon product ads and also using demand from various SSPs. UAM is an invitation-only solution and is compatible only with publishers using Google Ad Manager (GAM). While UAM provides an easy plug-and-play solution and access to buyers unreachable for small publishers, it lacks on log level data and transparency.

TAM on the other hand, is intended for enterprise publishers. It is also a server-side header bidding wrapper with direct demand from Amazon and the ability to onboard additional demand partners (per publisher request). It provides full control of setup details and auction-level reporting, but still has limited integrated demand partners comparing to Prebid.js.

What to look in a Header Bidding Wrapper

One of the major questions publishers eventually face: Open Source and in-house or outsourcing with a paid solution? Which is the way to go?

In-house or Outsource?

The answer depends on the current situation of each publisher. Is there enough resources and time available to get started with an open-source wrapper, like Prebid.js?

For a publisher who is struggling to answer yes, then the option of a vendor providing managed wrapper sounds ideal. The best part of this approach is outsourcing almost all setup, optimization and troubleshooting work to the provider. On top of this value-add features and automations, such as automated line-item creation, Lazy Loading functionality, advanced analytics and continuous support are some additional services a vendor can provide and persuade a publisher towards a managed wrapper. The only sure thing is, there’s no single method with no drawbacks.

Project Agora’s Header Bidding solution

Project Agora Header Bidding, our meta-header bidding solution, aims to provide the best for each publisher by integrating the most promising demand sources available, combining multiple header bidding implementations. We support client-side along with server-side header bidding using Prebid.js and other header bidding wrappers (e.g., Amazon). Being technologically neutral (and not relying on a single header bidding solution or method) we are working to either develop or integrate the best of technology solutions available out there, to help publishers take control of their advertising future.

Still thinking about this? Take charge of your advertising future today and see how your business can benefit from Project Agora.