willhaben on the frontline of first-party data: Lessons from a changing industry

As advertisers, publishers, and agencies alike navigate the latest changes in digital advertising, the shift from third-party to first-party data is gaining momentum. willhaben, Austria’s largest digital marketplace, has taken a hands-on approach in adapting to this transformation. Through ongoing collaborations, the company is finding ways to make privacy-compliant, data-driven advertising drive positive business outcomes.

What did the deprecation of third-party cookies mean for willhaben, and how has this industry shift influenced your data strategy?

Schatz: This change was teased for quite a while, so since 2020, we’ve prioritized maintaining robust first-party data to ensure control over our data while upholding user privacy. But even though we were proactive on that front, cookie deprecation still brought significant uncertainty. Advertisers suddenly faced increased difficulties in targeting and measuring their campaigns effectively, and that extended to us as a classified portal. We had to rethink our holistic data strategy, striking a balance between providing advertisers with valuable insights while ensuring user trust.

It hasn’t always been easy — many advertisers were hesitant to change their approach. Some still rely on third-party data and are unsure how to maximize the potential of first-party data. But we’ve been working to bridge that gap, testing new approaches for working together and educating our partners along the way. Having access to a provider that offers not only data collaboration technology but also guidance in implementation has been invaluable in this process.

What led willhaben to adopt Decentriq’s data clean rooms?

Schatz: We recognized early on that if we wanted to move forward with first-party data, we needed a privacy-secure way to collaborate with advertisers. Decentriq’s data clean room technology helped us do that without exposing sensitive information. And let’s be clear — no data clean room, especially one that is very thorough when it comes to data protection — is a plug-and-play solution. There’s a learning curve, and it requires effort from both publishers and advertisers to get the most out of it.

One major factor in choosing Decentriq was the level of support we experienced when working with their team. Data clean rooms are still relatively new technology, and proper preparation is key. Decentriq demonstrated their dedication from the very beginning, guiding us and our collaboration partners through the technology and first-party data activations — quickly becoming more than just a platform provider, but rather a trusted partner on our side.

The partnership turned out to be very effective and efficient for us. Not only did we not need to develop technical expertise from scratch, as the usage of the technology is very intuitive, but with the provided support, we could concentrate on what really matters, which is the pragmatic use of first-party data.

Can you share more about the success willhaben has had using Decentriq’s data clean rooms?

Schatz: One of our strongest cases so far has been our collaboration with IKEA. We securely combined our data sets to refine audience targeting and enhance campaign performance. The results were very impressive, as they demonstrated significant performance improvements in regard to multiple KPIs such as lower cost-per-visit (CPV), reduction in cost-per-action (CPA), and higher return on ad spend (ROAS).

The campaign’s success was recognized industry-wide, earning a WebAd Bronze award for Best Cookieless Solution. But while this was a great case, it’s important to note that it’s no longer a one-off. This type of collaboration is quickly becoming a regular part of publisher-advertiser relationships. The industry is realizing that first-party data isn’t just a fallback — it’s a strategic advantage.

What do you see as the future of data collaboration in digital advertising?

Schatz: I recognize the key role data clean rooms will play here, as well as the essential shift the technology is undergoing as the industry matures with regard to the use of first-party data. Not only do I expect data clean rooms to continue evolving, but I also expect significant improvements in the infrastructure between the single technologies to allow better connectivity and enable seamless collaboration.

The challenge isn’t just technological, though. Many companies still don’t have a clear first-party data strategy in place. If advertisers want to use data clean rooms effectively, they need to understand their own data first. That’s something we still see as a major roadblock. This is where strong partnerships matter — having a provider that not only offers the infrastructure but also guides you and your collaborators through the strategy is a crucial differentiator.

What are the key takeaways from willhaben’s experience with data clean rooms?

Schatz: One major takeaway is that this shift requires effort. There’s no quick fix, and publishers as well as advertisers need to be willing to experiment and refine their approaches. That said, the benefits are clear — better targeting, greater control over data, and a future-proof strategy as the industry continues moving away from third-party cookies.

As more businesses recognize the power of first-party data, data clean rooms are becoming less of an experiment and more of a necessity. At willhaben, we’re still learning, but we’re also seeing real results. The future of advertising isn’t just data-driven — it’s privacy-conscious, and that’s a shift we’re committed to navigating.

About willhaben

willhaben is Austria’s largest digital marketplace, connecting millions of users with more than 13 million listings across real estate, jobs, cars and motors and the free marketplace for private users. With over 3.8 million unique users per month (source: ÖWA 01/2025), willhaben plays a significant role in Austria’s digital economy. As one of the most widely used internet services in Austria, it is continuously adapting to the evolving digital advertising landscape, prioritizing user trust while exploring innovative first-party data strategies to enhance advertising effectiveness.

Learn more about how willhaben and IKEA achieved impressive results in our on-demand webinar.