The browser is no longer neutral ground for ad tech. Apple’s iOS 27 Safari update has started blocking domains tied to identity resolution providers such as The Trade Desk and ID5 — services that connect people’s browsing to their email addresses. The response from ad tech is blunt: move more of the ad-buying machinery out of the browser entirely.
The server-side push
IAB Tech Lab and ad tech companies are now accelerating work on server-side ad calls, with the group’s Trusted Server technology as a key proposal. The logic is straightforward: if the browser can block or inspect what happens on a page, shifting decisions to servers reduces that visibility and control.
But Digiday’s Seb Joseph and Ronan Shields caution against treating Trusted Server as a permanent fix. “It’s pretty clear that Apple is not going to stop at the companies that it has already targeted,” Joseph said. The same underlying concern — Apple does not want this identity linking happening to its customers — applies whether it runs in Safari or on a server.
Google and the Prebid opening
The Google ad tech antitrust remedies ruling has created another server-side opening. Prebid could flip the programmatic auction so that Google’s ad exchange must bid into Prebid’s server, instead of Google’s ad server having the final say on the winning bid.
Shields noted that Google’s third-party display network business again underperformed in the company’s latest earnings, reported Oct. 28, and suggested Google may not lose much sleep if Prebid takes it. Even so, the panel argued that ad tech cannot truly wrest control from Apple and Google. They own the browsers, mobile operating systems and, in Google’s case, much of the advertising and cloud infrastructure.
Why marketers should pay attention
For marketing teams, this is a warning about the fragility of identity-based targeting. A campaign built on email-linked audiences may look very different tomorrow if a dominant browser decides the practice is off-limits. The server-side shift may preserve some data flows, but it is not a guarantee of continuity.
- Audit which identity providers in your stack use browser-side signals.
- Ask your ad tech partners how they will operate if Safari or Chrome changes the rules again.
- Diversify measurement beyond device- or email-level matching where possible.
The trust question
Joseph raised a broader point: the industry may need to go beyond regulatory minimums to earn trust, otherwise browsers and platforms will keep finding ways to put a hand on the scale. Whether ad tech uses its new autonomy carefully or repeats the patterns that invited scrutiny is the real test behind the server-side shift.
For advertisers, the practical read is not to abandon current campaigns, but to build in resilience. Treat identity graphs and server-side workarounds as tactics, not strategy — and keep a close eye on how Apple and Google enforce the next set of rules.
Source: Digiday
