ID Bridging Debate Brings About New Transparency Standards From IAB Tech Lab

The IAB Tech Lab introduced standards earlier this month that aim to make the process of declaring an identifier more transparent—a hot-button issue that has been dividing the adtech community for months.

Earlier this year, the buy side called out publishers and their tech partners for using deceptive practices to identify audiences.

At the center of these accusations is ID bridging, where a publisher will link a user in a cookieless environment, like Safari or iPhone, to who they are on Chrome. A demand-side platform might think that it is bidding on a Chrome user with a cookie, but it is really bidding on a user whose identity is inferred. DSPs argue that this undermines campaign performance and can lead to fraud.

Many on the sell side rely on these techniques to monetize audiences that wouldn’t ordinarily be addressable. They counter that DSPs should be aware.

To help clear up the mess, the IAB Tech Lab has provided a forum for these debates since February.

Those conversations have resulted in new protocols, first described in an IAB Tech Lab blog post May 8 written by Mike O’Sullivan, co-founder of metadata firm Sincera. The new specs are in public comment until June 10.

The new protocols

The IAB proposed an update to a standard that was implemented in 2022.

That standard prompted publishers to use the Extended Identifiers (EID) field in a bid request to identify the use of alternative IDs, such as UID2, RampID or ID5, using code read by the DSP. The typical place for DSPs to view the use of identifiers in the bid request—which, up until recently, mostly meant third-party cookies—was a separate field called the buyeruid field.

With the May 2024 update, publishers can only place identifiers in the buyeruid field that are specifically agreed upon by the buyer and seller. In practice, this means that the buyeruid field is reserved for cookies, and the EID field contains all other alternative IDs.

Confusion has arisen when sellers place a non-cookie solution, like ID bridging, in the buyeruid field. Under the new standard, this is fine, as long as the buyer and seller explicitly agree on using this ID.

The protocol also includes new ways for publishers and their tech partners to use the EID field to specify if and how they’re using ID bridging.

“We are now clarifying that buyeruid is intended as an explicit mapping as agreed upon by buyer and seller,” said Anthony Katsur, CEO of IAB Tech Lab. “There were a lot of assumptions on both side of the ecosystem.”

Whitewashing bad behavior

The IAB Tech Lab’s standards make it easier for publishers and supply-side platforms to declare which method they’re using to identify users as the number of identifiers proliferates. It stops short of declaring which method is best.

“It’s about disclosure,” Katsur said.

This is frustrating for some on the buy side who see all ID bridging as fraud and want to clamp down on publishers sending bridged IDs.

“It’s sort of whitewashing the behavior,” said a DSP adtech source who didn’t want to be identified because of sensitive industry relations. “I don’t like that it seems like people are being rewarded for their fraudulent behavior by getting an extension to the spec.”

This source intends to ignore EID bids with apparent ID bridging.

At stake for publishers is a real loss of revenue. ID bridging makes “substantially” more inventory available to publishers because it allows greater monetization of previously non-addressable environments, like Safari, said Paul Bannister, chief strategy officer at publisher network Raptive.

Even DSPs not ideologically against ID bridging still use algorithms that generally prefer to bid on cookies, putting bid requests with different identifiers at a disadvantage. That dynamic is what incentivized publishers to place ID bridges in the buyeruid field in the first place.

“Would my company’s life be a little bit easier if the buyeruid [field] could keep having bridged IDs?” Bannister asked rhetorically. “But I understand the perspective of the buy side. It will create more work for the sell side, but it is in the interest of the larger ecosystem.”

Implementation remains a question

IAB specs like this one are only rules on paper. They only really affect the ecosystem if adtech companies enforce them. Lagging enforcement and adoption have long hampered other standards like those on online video.

It remains to be seen if DSPs interpret these standards by checking that the fields are labeled correctly, ignoring EID fields with ID bridging present and only bidding on requests via the buyeruid field, where cookies are present.

Plus, while the delineation between the buyeruid and EID fields is now clearer, this breakdown may no longer matter once cookies are deprecated.

Katsur said that if in the years after cookies are deprecated, the industry stops using the buyeruid spec, the tech lab would consider new standards.