The downside was that making all of those ad calls at the same time slowed down page load times since the original format of header bidding hosted the ad calls on users’ browsers.
To mitigate these latency problems, a little over a year ago, several ad tech vendors created header bidding products that hosted the ad calls on web servers. Moving ad calls from people’s browsers to servers significantly reduced page load times. Industry insiders speculated that this new form of header bidding, called server-side bidding, would replace browser-side header bidding.
Rather than replace browser-side header bidding with its server-side cousin, many publishers are adopting both technologies. The growth in server-side bidding is being driven by Amazon’s Transparent Ad Marketplace, which is the most popular server-side product in the ad industry, according to ServerBid.