Real-World Impact of Cookieless Advertising Revealed in Latest highfivve A/B Testing using Pubstack’s Platform

In an era where digital privacy concerns are reshaping the advertising landscape, highfivve, a spin-off of gutefrage.net GmbH, one of the largest German publishers, has unveiled compelling evidence of the impact of cookieless advertising on revenue. Through an extensive A/B test on Pubstack’s platform, the partnership has provided concrete data demonstrating how the lack of identifiers affects Cost Per Thousand Impressions (CPM). 

The study, conducted from December 9th to February 7th, meticulously analysed ad performance across the gutefrage.net logged in and logged out traffic. By segmenting participants into four groups — from normal ad setups to those devoid of contextual signals or identifiers — the test revealed differences in advertiser bid rates and bid CPMs. The test environment was on Safari and Firefox, because these browsers already do not support 3rd party cookies. The browser Chrome was not part of the test. 

Key findings: 

For selective bidders: Advertisers strategically adjust bidding practices in response to limited data, prioritising certain impressions. 

For bidders' decreasing rate and CPM: A conservative shift in bidding strategy reflects heightened caution amidst data scarcity. 

For bidders focusing on quality: A trend towards higher-quality, albeit fewer, impressions emerges, particularly on browsers like Chrome, indicating a reassessment of value in a data-restricted environment. 

The comprehensive A/B testing conducted on Pubstack’s platform by highfivve revealed that reducing data availability to advertisers — via removing identifiers and contextual signals—significantly impacts bid rates, with a pronounced effect on Safari users. This finding underscores the high value advertisers place on such data for bid placement decisions. 

Furthermore, the observed variability in bid CPM and the differential impacts across websites and browsers underscore the complexity of advertising performance in a cookieless world, highlighting the intricate interplay of browser type, ad unit specifics, and advertiser behaviour. 

Martin Pichler, chief sales officer at gutefrage.net & highfivve, comments, “In cooperation with our parent company gutefrage.net, one of the leading German publishers, we successfully conducted a cookieless A/B test and analysed it in detail with the help of Pubstack. We are delighted to observe the affirmative influence of identity solutions on cookieless inventory. Anticipating a growing trend, we foresee the demand side increasingly embracing identity solutions and, as a next step, contextual signals throughout 2024 to effectively bridge the existing gap in a cookieless world.” 

Loïc Sfiligoi, co-founder and CEO of Pubstack, remarks, “Pubstack’s role in facilitating this crucial A/B test underscores our commitment to empowering publishers in the cookieless era. Our platform provided the robust infrastructure needed for our customers to explore and understand the intricate dynamics of advertising revenue without traditional identifiers, highlighting our dedication to innovation and data-driven solutions in ad management.”


Pubstack, established in 2018 in Paris, is a web publisher Ad Management platform collaborating with 100+ European premium publishers. It revolutionises Ad Management by using a data-driven approach to build, maintain, optimise, and monitor ad sta...
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