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Tags: Programmatic, Publisher, Header Bidding, Ad Serving, Relevant Yield

More than 70% of publishers use header bidding to boost eCPMs, increase fill rates, and maximize revenues. These calls can be made either client-side or server-side; or even as parallel calls. Here we explain how it works, and what the benefits are; with a focus on the server-side header bidding.

What is the difference between Client-side Header Bidding vs Server-side Header bidding?

In server-side header bidding, the publisher chooses a server-side bidding technology partner to implement and host the solution; or they build this server structure themselves - often using the Prebid Framework.

A single call is made from the web page or application to a server, which then continues making calls server-side to all integrated demand sources. The “wrapper” sends all bids and prices back to the publisher, so pricing is transparent. This is especially great for mobile, where high bandwidth is necessary to sustain the connection and ensure the ads are properly delivered. This is different compared to a client-side call, where all calls are being made from the users browser, which in most cases take slightly longer. 

Several ad tech providers developed their own wrappers for client-side header bidding, and a few also support server-side header bidding. The Relevant Yield solution can do both, and it is done quite easily by clicking a button, and selecting if you want to do a client-side call, a server-side call - or both in parallel. It might seem counterintuitive to call both client- and server-side with the same call, but different SSPs are focusing bid strategies on different call types, and some are just stronger in one call type, than the other; so it is certainly a good idea about testing the performance, in all options. More about performance uplifts later on though!

One major difference is of course also that if there is no client browser, the prebid server is the natural solution. Relevant Yield wrapper HB Manager supports server side, working with the prebid framework, and supports all of the server-side components in the framework:

  • Prebid server
  • Prebid Mobile
  • Prebid Video

Where the latter two are extensions for the core prebid server basically.


What are the advantages of server-side header bidding through HB Manager?

  • A solution for latency issues - faster loading of ads. 
  • Why does it work better for Rich Media: Videos are often slow to load, so switching to server-side bidding greatly improves user experience. A server-side implementation is also the only way to show ads on Over-the-top (OTT) devices.
  • Unified Header bidder reporting through our HB Analytics solution, which covers both client-side and server-side header bidder reporting.
  • Easy set-up: Identical setup as the client-side and no extra mapping; just activate with a single button if you want to run with the same settings as client-side. You can also differentiate your demand sources based on which call type you utilize, making sure you work with the best sources in each individual case and mediatype.
  • Switch between methods by pressing a button, or even run in parallel. You can mix load types on a placement level, really customize your website, to utilize the perfect call structure on each individual level.

What are the drawbacks of server-side header bidding?

  • Lower levels of users that are cookie synced in the server-side-calls might be seen in the beginning after enabling prebid server as during the first auction synchronization of cookies has not been completed yet.

Uplift revenues with HB Manager

Page speed in general is a highly important factor in generating a good user experience and in order to make sure your ad stack performs well. Advertisers and agencies are willing to pay higher prices and bid more often on inventory that has high viewability levels, and with a slow site that becomes difficult to achieve.

In order to maintain good site speed, there is a limit of how many bidders you can run client-side as all add a bit of latency to the setup. With server-side setups such limitation does not exist as the auction is held on a separate server, which enables you to have a larger number of demand partners running without a negative impact.

The HB Manager enables you to do flexible testing and experimenting with different options; You can easily change the configuration from the UI on whether a bidder should run client-side or server-side. This enables you to find out what the optimal setup is for you; how many bidders should I run client-side vs server-side? What impact does it have on page speed if I decrease the number of client-side bidders and does it generate a desired uplift in KPIs? 

Interested in a free consultation on how your company will benefit from using Relevant Yield?

Read more about our solution: Relevant Yield

If you are interested in hearing more about our services, you can leave a contact request here.

Suvi Leino
By: Suvi Leino

Responsible for marketing and communications at Relevant Digital.


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