The IAB Tech Lab is pushing back against Prebid.org’s change to the transaction ID (TID) in Prebid.js.
In a statement issued by CEO Tony Katsur, the Tech Lab said the update—making TIDs unique for each bidder rather than consistent across exchanges—is “materially non-compliant with the OpenRTB specification.” Katsur warned that unilateral changes risk “undermining the integrity and consistency of open technical standards” that are essential for programmatic interoperability.
Here’s Tony’s full post on X:
The @IABTechLab must clearly state that the recent change in Prebid’s implementation of the Transaction ID (tid) is materially non-compliant with the OpenRTB specification. The Tech Lab does not endorse this approach, as it risks undermining the integrity and consistency of open technical standards that are critical to interoperability across the programmatic ecosystem.
We fully recognize the tension that the tid field has caused within the publisher community. However, making unilateral changes outside the bounds of the specification creates fragmentation and uncertainty for buyers, sellers, and intermediaries alike. The right path forward is not to bypass or reinterpret the specification, but to work collaboratively on it.
The Tech Lab stands ready to convene a dedicated forum with publishers, buyers, and technology partners to chart a path forward that addresses the underlying industry concerns while maintaining compliance with OpenRTB. We call on all stakeholders to engage in this process so that we can deliver clarity, consistency, and durable solutions that strengthen the marketplace rather than fracture it.
Why This Matters:
The TID was widely used to de-duplicate auctions and improve supply-path transparency. Prebid argued that cross-exchange TIDs posed a privacy risk, potentially allowing you to stitch requests together. But the Tech Lab’s stance highlights the tradeoff: changing implementation so suddenly creates fragmentation, confusion, and uncertainty for everyone — buyers, sellers, and intermediaries.
Experts React:
Industry debate is unfolding in real time on this one. Ari Paparo first flagged the change, sparking wide reaction. See his thread here:
Also, note these other posts for more discussion:
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Our Take:
Prebid wanted to reduce perceived privacy risk, but in doing so may have fractured an important piece of adtech auction mechanics. With the IAB stepping in, the next phase will focus on whether the industry can align on a standards-based fix or if fragmentation becomes the new reality.
