Real-Time Real Talk

Real-Time Real Talk: Prebid.js

“Real-Time Real Talk” is an ongoing blog series that seeks to clarify the “what”, “why”, and “how” behind ad-tech innovations.

Blog Post
The AppNexus Team

Prebid.js is a free header bidding wrapper developed and incubated by AppNexus. But before we tell you all about it, let’s take a step back and talk about what header bidding wrappers are and why publishers use them in the first place.

Publishers began adopting header bidding way back in 2015 with great results, but there was one key problem: There was no simple way for publishers to manage their header bidding integrations with all the demand partners they wanted to work with. For each new partner, publishers had to add new code their site, keep it bug-free and updated, and make sure it wasn’t adding latency – all very difficult and time-consuming.

Enter the header bidding wrapper. The wrapper is a single piece of code that holds the tags for all of a publisher’s header bidding demand partners, making it easy for publishers to add partners according to their needs and manage the integrations on an ongoing basis.


Makes sense. Have publishers had any trouble with header bidding wrappers?

When header bidding first started, most publishers were building their own wrappers from scratch and reverse engineering adaptors for every demand source they wanted to work with. But even when they got a wrapper from a third party vendor, many publishers found that these vendors were unreliable at keeping their adaptors updated.

Trust has been another issue with header bidding wrappers. Publishers are rightfully wary of putting another provider’s code on their page, especially if they can’t see that code for themselves. What if it has bugs? What if it slows down their site? What if it favors some demand sources over others, thereby negating header bidding’s promise of open competition between all demand sources? These are all questions that have publishers sweating as they evaluate wrappers.

Finally, consider the fact that we’re still in the early days of header bidding. Publishers need a wrapper with a strong product road map that’s poised to remain relevant in the industry for the long term. Otherwise, they could find themselves having to implement all over again with a new provider.


So, how is Prebid different from any other header bidding wrapper?

The biggest difference between Prebid and other header bidding wrappers is that it’s open source. Anybody can view, edit, or build on top of the code, which means publishers can be sure that it won’t hurt their site’s performance or create an uneven playing field for their demand partners.

Open source solutions are also known for the developer communities that form around them, and Prebid is no different. Since we launched Prebid, over 130 people have contributed to its codebase–that’s 130 pairs of eyes scouring for bugs and building improvements, so publishers can have a higher degree of confidence that Prebid is technically sound.

Prebid is also designed to be easy to use. It doesn’t take as much custom coding to set up as other wrappers, and there’s extensive documentation to help publishers get started. Prebid also has the biggest repository of pre-built adaptors, most of which are maintained by the demand partners themselves, so publishers are spared the extra work of maintaining them on their own.


What are Prebid’s plans for the future?

At the latest AppNexus Summit in London, we announced that Prebid users can now implement server-to-server header bidding with the launch of Prebid Server. Server-side integration is the latest evolution of header bidding technology, and should be a great way for publishers to further reduce latency. Beyond that, we’re setting the stage for Prebid to bring header bidding and its associated benefits to formats like video, native, and mobile app.

We’re also excited to say that some of the biggest players in the industry are supporting this project. Facebook, Index Exchange, and Pubmatic will all be making their demand available through Prebid, giving publishers access to the largest header bidding marketplace available. With the resources of four well-established ad tech companies, a commitment to remain open and transparent, and a constantly-evolving product road map, we’re confident that Prebid is here to stay.


Whether you use Prebid or not, download our newest white paper to learn everything you need to know about header bidding, including how to choose your demand partners, what server-to-server can do for you, and why header bidding makes sense for formats like video, native, and mobile.