Advertisers face a hindrance as Prebid disables its real-time bidding tracking system, potentially disrupting the process of buying online ad spots.

In a move that has sparked controversy within the advertising industry, Prebid.org, a leading open-source advertising technology organisation, has decided to disable the cross-exchange functionality of transaction IDs on August 27, 2025.

This decision, which represents the first major public disagreement between Prebid.org and a key industry implementation, has far-reaching implications for demand-side platforms, publishers, and advertisers alike.

Transaction IDs, a tool that allows demand-side platforms to recognise duplicate auction opportunities and prevent wasteful spending, have been an integral part of many bidding algorithms and optimization strategies. The removal of this feature will significantly impact the industry, particularly for publishers using Prebid Server integration, where implementation options remain limited.

The change has revealed the magnitude of auction duplication, with one Roku device in a household receiving 1.7 million bid requests in a single day. However, this duplication of bidding increases the volume of bid requests that demand-side platforms must process, potentially straining technical infrastructure.

Advertisers who had begun incorporating transaction ID data into their programmatic operations must now rely on less precise alternative methods. The removal of transaction IDs affects advertisers' ability to optimize their bidding strategies and understand supply chain mechanics that influence auction dynamics and pricing.

The IAB Technology Laboratory, a global industry organisation that develops standards for digital advertising, has condemned the change as violating established specifications. Michael Sullivan from The Trade Desk, a prominent figure in the industry, mentioned that 59% of bid requests included transaction IDs before the change.

The incident raises questions about governance processes in open-source advertising technology development. Some publishers, who benefit from auction duplication as it increases their effective yield by creating additional bidding opportunities, have expressed concerns that transaction IDs threatened this advantage.

Publishers who invested engineering resources in transaction ID support based on OpenRTB specifications now face technical debt from the standards change. On the other hand, Brian O'Kelley, another industry leader, predicts that the development could accelerate direct supply relationships between demand-side platforms and publishers, potentially bypassing traditional programmatic intermediaries.

Notably, major publishers like The New York Times, CNN, Forbes, Fox News, BBC, and Reuters implemented transaction ID functionality. However, beyond these names, no other major publishing groups were specifically named by Michael Sullivan in a recent Marketecture podcast episode regarding the use of Transaction IDs. The discussion focused broadly on publisher resistance and market impacts without listing additional large publishers by name.

The breaking change nature of this decision means existing implementations cease functioning as intended, requiring publishers to evaluate whether continued transaction ID support provides any remaining value under the new limitations. The IAB Tech Lab's direct challenge to a major implementation decision has also created industry uncertainty about how similar conflicts will be resolved in the future.

Advertisers face a hindrance as Prebid disables its real-time bidding tracking system, potentially disrupting the process of buying online ad spots.