In programmatic advertising, sales have long relied on client-side implementations, where the auction and ad serving take place in the browser. This has enabled relatively easy adoption and effective targeting, but at the same time has given a lot of power to browsers and third parties. Server-side implementations can change this dynamic: the auction and the attachment of the ad to the content move to the server, either in the publisher’s environment or one managed by a partner.
This setup gives the seller more control, better technical performance, and a safer environment from a data privacy perspective. Despite the positive promises, many have not yet tested server-side solutions or hesitate to adopt them — likely in part due to the resources required for implementation and maintenance.
We spoke with Petri Kokkonen, CEO of Relevant Digital, about the current state of server-side technology, the significance of the Trusted Server standard, and the opportunities and risks these bring to publishers now and in the future. Below are the key takeaways: why server-side has not yet reached the same commercial benefits as client-side, what advantages it already offers, what is needed for broader adoption, and what the future looks like.
Why doesn’t server-side yet deliver the same commercial benefits as client-side?
“From a technical perspective, server-side works very well in programmatic advertising. The challenge, however, is that the commercial outcome usually does not yet reach the level of the client-side. One reason is the limited availability of targeting data. On the server side, it’s not possible to leverage the third-party data familiar from the browser side, which still operates at sufficient scale. The situation is improving all the time, though — first-party data is being used more and more, ID technologies are evolving, and contextual targeting is making at least a modest comeback,” Petri explains.
“From a targeting perspective, client-side remains stronger, at least as long as familiar and easy-to-use third-party cookies provide significant added value. But in mobile apps and CTV, the situation is different: there, server-side has always been the only implementation option, since a ‘browser’ is not available. Server-side, however, already offers other advantages whose importance will likely grow in the future, and which some publishers are already making use of in their daily operations.
For publishers operating in browsers, the winning setup in terms of revenue is still a combination of client- and server-side. Programmatic may move entirely to servers in the future — which would also bring the bonus of slightly faster setups and a more hygienic environment from a data perspective — but for now, it’s best to use both whenever possible.
Moving programmatic sales to the server side can cause technical challenges and add costs. If you want to handle everything yourself, you need expertise and continuous maintenance. But there are good partners who make implementation, daily operations, and optimisation easier.”
Trusted Server – more than just programmatic auctions
Recently, IAB has started talking about the Trusted Server standard – but what is it really about?
Trusted Server and Prebid Server are two different things and should not be confused. “Prebid Server is an open-source solution that moves the auction from the browser to the server, but it focuses specifically on executing the programmatic auction. The IAB Tech Lab’s Trusted Server initiative, on the other hand, is not only about auctions. At the moment, the ad is attached to the content in the browser, whereas the idea of the Trusted Server standard is to manage all ad-serving operations on the server side,” Petri explains.
This approach is already commonplace in, for example, CTV and retail media. Ad breaks are constructed on the server and delivered as complete packages to the smart TV. In retail media, ads are combined with search results server-side before being shown to the customer.
“Trusted Server brings this logic also to traditional display advertising. It speeds up the entire delivery chain and returns control to the publisher, since ad placement, measurement, and optimisation all happen entirely in an environment managed by the publisher – not in the browser. This way, the publisher controls the quality of the entire delivery chain,” Petri notes.
What does the adoption of Trusted Server require?
“We are still at an early stage. The standard is at a proof-of-concept level, and for example, the details of campaign measurement have not yet been solved,” Petri notes.
Widespread adoption requires, above all, solving measurement issues, ensuring data mobility, and securing industry-wide support. A potential shift to the server side may face resistance, especially from players who see their current position or business model threatened. In addition, new technical expertise, development resources, and infrastructure will be needed. For smaller players, this may become a critical barrier unless ready-made service packages or partnership models are available.
Is the future of programmatic advertising server-side focused?
“If browser-side challenges such as cookie restrictions, the rise of ad blocking, and technical limitations continue to grow, it’s worth asking whether client-side is still worth the effort. I believe that in a few years, the focus will shift even more strongly to server-side. Running Prebid server-side is already becoming fairly common, but whether we’ll also see display ad servers moving to the server side remains to be seen,” Petri reflects.
According to Petri, the most significant risk is a poorly executed transition, which would strengthen the power of the walled garden giants. The most important opportunity, on the other hand, lies in returning control to sellers, improving inventory quality, and increasing its volume. Server-side and Trusted Server are therefore not just technical answers to today’s challenges – they have the potential to define the direction of the entire ecosystem. When ad delivery and measurement move to the server, publishers can take back control and build higher-quality, smoother, and fairer advertising.
At Relevant Digital, we are closely following these developments. Our CPO, Ronny Linder, is part of IAB Tech Lab’s Trusted Server task force, giving us first-hand insight into how the standard is progressing. We’ve been involved in Prebid’s server-side development from the very beginning, and our tools enable you to easily implement server-side, test it, and determine the best setup for your specific environment.
If you’re considering server-side testing or want to spar on the topic, don’t hesitate to get in touch – we’re happy to help.