Header Bidding: What Is It and How Does It Work?

Last Updated: May 23, 20246.8 min readCategories: Marketing, Programmatic Advertising

In the rapidly evolving landscape of digital advertising, header bidding has emerged as a transformative technique for maximizing ad revenue. By allowing multiple demand sources to bid simultaneously on ad inventory, this method enhances competition and transparency.

This article explores the header bidding definition, explains its mechanics, and highlights its benefits and implementation strategies.

What Is Header Bidding?

Header bidding is a programmatic advertising technique where publishers offer their ad inventory to multiple ad exchanges and demand-side platforms (DSPs) simultaneously before making calls to their ad server.

This process increases competition and transparency, leading to higher ad revenues for publishers. Unlike traditional methods, header bidding allows all bidders to compete equally at the outset.

Header Bidding vs Real-Time Bidding

Real-time bidding (RTB) is a programmatic waterfall model where ad inventory is offered to advertisers one at a time based on predefined priority levels.

The primary difference is that header bidding allows multiple advertisers to bid simultaneously, increasing competition and maximizing revenue. In other words, header bidding improved the process of real-time bidding.

Header Bidding vs Open Auction

Open auctions are public auctions where ad inventory is sold to the highest bidder in real-time, typically within an ad exchange.

The main difference is that header bidding conducts the auction before reaching the ad server, enabling simultaneous bids from multiple sources and potentially higher revenues.

Advantages of Header Bidding

Header bidding offers several advantages that can significantly enhance the revenue and efficiency of digital advertising. Some of its benefits are:

1. Increased Revenue

By allowing multiple demand sources to bid simultaneously, header bidding creates a more competitive environment. This competition can drive up the price of ad impressions, maximizing publisher revenue and ensuring better returns on their ad inventory.

2. Improved Transparency

Header bidding offers greater transparency in the bidding process. Publishers can see bids from multiple advertisers at once, making it easier to understand the true market value of their inventory and make more informed decisions.

3. Better Inventory Management

Header bidding allows publishers to have more control over their ad inventory. This provides the ability to manage and optimize ad placements more effectively, ensuring that the most valuable inventory is sold at the best possible price.

4. Access to Premium Demand

By opening up their inventory to a broader range of demand sources, publishers can attract more premium advertisers. This access to high-quality demand can lead to better ad placements and increased revenue from top-tier advertisers who may not have been accessible through traditional methods.

5. Cookie Matching

Since the bidding process typically occurs in the browser, AdTech vendors for both publishers and advertisers can synchronize their cookies. This synchronization allows advertisers to identify users on the publisher’s site, enabling more effective targeted and retargeted ad campaigns, which can lead to increased revenue for publishers.

Disadvantages of Header Bidding

Despite its benefits, header bidding comes with a few disadvantages that publishers need to consider.

1. Latency Issues

Although header bidding can reduce latency compared to sequential bidding, the increased number of simultaneous requests can sometimes slow down page load times. This can negatively impact user experience if not properly managed.

2. Compatibility Issues

Client-side header bidding must work with various browsers, including older versions, which can present challenges. Additionally, some browsers may limit or block connections to external pixels, potentially disrupting the efficiency of header bidding auctions.

3. Risk of Duplicate Bids

When a publisher uses multiple header bidding partners, the same impression might be offered for sale multiple times. This duplication can lead to processing multiple bids for a single impression, which can occur in both client-side and server-side implementations.

4. Limited Ad Requests

Browsers can only handle a certain number of requests at once, limiting the number of ad requests a client-side header bidding wrapper can send to around a dozen. This constraint can affect the overall efficiency of the bidding process.

5. Potential for Ad Fraud

The complexity of header bidding can also increase the risk of ad fraud. Without proper monitoring and fraud prevention measures, publishers may be vulnerable to fraudulent activities that can affect their revenue and reputation.

How Does Header Bidding Work?

Header bidding involves multiple components working together to create a more competitive and efficient bidding environment for digital ad inventory. Understanding the roles of these key components is essential for grasping the mechanics of header bidding.

Header Bidding Wrappers

Header bidding wrappers are JavaScript codes implemented in the header of a webpage. They manage multiple header bidding partners, streamline the auction process, and ensure that bids are collected and processed efficiently, ultimately deciding which bid is sent to the ad server.

Demand-Side Platforms (DSPs)

DSPs are platforms that allow advertisers to purchase digital ad inventory through automated, real-time bidding. In header bidding, DSPs place bids on ad impressions simultaneously, increasing competition and potentially driving up prices.

Supply-Side Platforms (SSPs)

SSPs are platforms that help publishers manage and sell their ad inventory programmatically. They play a crucial role in header bidding by sending bid requests to multiple DSPs at once, facilitating a more competitive auction environment.

Ad Exchanges

Ad exchanges are digital marketplaces where ad inventory is bought and sold in real-time auctions. In header bidding, ad exchanges facilitate the auction by receiving bids from DSPs and determining the highest bidder before the ad call reaches the publisher’s ad server.

Ad Servers

Ad servers are platforms that deliver ads to websites and track their performance. In header bidding, the ad server receives the highest bid from the wrapper and serves the ad, ensuring that the most competitive bid wins the impression.

Content Delivery Networks (CDNs)

CDNs are networks of servers that deliver web content to users based on their geographic location. In header bidding, CDNs can help reduce latency and improve the speed of ad delivery, ensuring a smoother user experience.

Types of Header Bidding

Header bidding can be implemented in different ways, primarily through client-side or server-side methods.


In client-side header bidding, the auction occurs in the user’s browser. JavaScript code in the webpage header sends requests to multiple demand sources simultaneously, but this method can increase page load times due to the additional network calls.


Server-side header bidding moves the auction process to an external server, reducing the load on the user’s browser. This method can decrease latency and improve user experience, but it may offer less transparency compared to client-side bidding.

Header Bidding Platforms

Numerous platforms utilize header bidding technology to enhance ad revenue and optimize bidding processes.

  • Amazon: Amazon’s Transparent Ad Marketplace (TAM) leverages the company’s vast infrastructure to provide low latency and high bid density, ensuring superior ad performance and maximized revenue.
  • Index Exchange: Known for its transparent and efficient operations, Index Exchange offers robust header bidding technology that focuses on yield management and ensuring fair market value for publishers.
  • Magnite: Formed from the merger of Rubicon Project and Telaria, Magnite delivers comprehensive header bidding solutions that integrate video and connected TV, catering to a diverse range of digital advertising needs.
  • PubMatic: This platform stands out for its cloud infrastructure, which offers scalable and advanced header bidding solutions that help publishers optimize their ad revenue and manage inventory more effectively.
  • Xandr: As a part of AT&T, Xandr, formerly AppNexus, combines robust header bidding technology with extensive data insights, enhancing the efficiency and effectiveness of programmatic advertising.
  • OpenX: OpenX is notable for its hybrid approach, integrating both client-side and server-side header bidding to increase competition and drive higher revenues for publishers.
  • TripleLift: Distinguished by its native advertising capabilities, TripleLift enhances header bidding by seamlessly integrating visually appealing native ads, boosting user engagement and ad performance.
  • Sharethrough: Specializing in native and video advertising, Sharethrough utilizes header bidding to deliver high-quality ad experiences, ensuring better visibility and revenue outcomes for publishers.

Header Bidding: Final Thoughts

Header bidding has revolutionized the digital advertising landscape, offering publishers a powerful tool to maximize ad revenue through increased competition and transparency. By understanding the key components and advantages of header bidding, as well as its potential drawbacks, publishers can make informed decisions about implementing this technology.

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