Header bidding is a programmatic advertising technique that allows publishers to offer their ad inventory to multiple demand partners simultaneously, maximizing revenue and increasing transparency in the bidding process.

What is Header Bidding?

Header bidding is a programmatic technique that allows publishers to offer their inventory to multiple ad exchanges at the same time before making ad calls to their servers. This is the opposite of the traditional waterfall method, which involves offering the same impression to a chain of ad networks in sequence.

How Does Header Bidding Work?

Header bidding relies on a piece of JavaScript in the publisher’s header tag, which enables buyers to bid while the rest of the page content loads. When a user visits a web page, the header tag connects the user to multiple ad networks (exchanges, SSPs, DSPs), which place their bids. The winning bid is returned to the user, who passes the bid to the publisher’s ad server, and the final creative is displayed. This entire process occurs within fractions of a second.

Benefits of Header Bidding for Publishers

  1. Increased choice of demand: Header bidding allows publishers to integrate with multiple demand partners and SSPs more quickly and easily, increasing the range and variety of demand available to them.
  2. Transparency on what was bid: Header bidding provides increased transparency into how much impressions are worth, as publishers can sell their inventory on a per-impression basis.
  3. Eliminates ‘passback’: Header bidding eliminates the need for pushing inventory back and forth, which can be inefficient and wasteful.
  4. Better yield management & revenue increase: By letting multiple bidders bid simultaneously on the same inventory, publishers increase their yield and their revenue.

Benefits of Header Bidding for Buyers

  1. Access to more inventory: Header bidding code enables buyers to see a publisher’s entire inventory, providing a better understanding of their reach and access to more audiences.
  2. Forecasting avails: More consistent inventory over time means better and more accurate forecasting for campaigns and media planners.

Open Bidding vs. Header Bidding

Header bidding, or pre-bidding, is an advanced programmatic technique that opens your inventory to multiple demand partners before sending the call to the ad server. Google’s Open Bidding, on the other hand, is a server-side unified auction where ad exchanges and SSPs compete alongside Google’s Ad Exchange (AdX) to win impressions, similar to header bidding. The key distinction is that the auction takes place on the server-side instead of the client-side.

Header Bidding

In the header bidding process, ad requests from your ad server are sent simultaneously to several demand partners. Each time an ad request is sent, the header tag initiates the auction, collects bids from all demand partners, and passes the highest bid to the ad server. The ad server then compares the highest bid with sponsored, direct, or programmatic deals and serves the ad creative to the user. This competition with the ad server’s demand increases eCPM and revenue substantially.

Implementing header bidding helps avoid the waterfall setup of ad servers and Google AdX privilege, leading to better revenue and a level playing field. As a result, publishers have seen improved ad revenue without increasing the number of ad units.

Open Bidding

Google’s Open Bidding is a server-side unified auction, where Ad Exchanges and SSPs compete with Google’s Ad Exchange (AdX) to win impressions. The main difference is that the auction occurs within the GAM (ad server), not on the user’s browser. 

Client-Side vs. Server-Side Header Bidding

Client-side header bidding can increase the latency of page and ad load times due to multiple advertisers connecting to the header bidder wrapper directly, running JavaScript on the page. Server-side header bidding, like Google’s AdX, tackles the latency problem by hosting the auction process in the cloud on an external server. Luna Media supports server-side header bidding and uses solutions such as Prebid Server to Server (S2S) to provide an efficient and effective bidding process for their clients.

Luna Media implements both client-side and server-side header bidding to take advantage of higher cookie-match rates, higher CPM rates, increased transparency, better-targeted ads, and an overall higher fill rate.


Header bidding has revolutionized the ad ops space, offering publishers more control, transparency, and higher revenue from their ad inventory. Advertisers also benefit from header bidding as they gain access to premium inventory that was previously only available through direct sales. 

Even though header bidding increases the revenue by up to 60 percent, publishers still need to partner with the SSPs to get the results.  Luna Media provides header bidding solutions for digital publishers worldwide, helping them capitalize on the benefits of this advertising technique.

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