Apple's Safari blocklist pushes publishers back to Trusted Server

Apple's iOS 27 began blocking data and identity vendors inside Safari without warning, and AdExchanger reported that the list could extend to hundreds of ad tech, martech and identity companies that handle user data. The Trade Desk's adsrvr.org was removed in the iOS 27.2 WebKit beta, but the fix may not reach live devices for three or four weeks. One engineering leader told AdExchanger the block hit like a heart attack: "Very subtle, easy-to-ignore signals; then all of a sudden." Digiday reported that publishers are revisiting IAB Tech Lab's Trusted Server, which moves ad requests and identity work onto servers the publisher controls, because Apple cannot block what it cannot see. AdTechRadar reported IAB Tech Lab CEO Anthony Katsur is pointing the industry at Trusted Server, an open-source framework introduced in March 2025, as the practical response.

The crux

A browser vendor changed the terms of programmatic trading inside Safari without notice, and the only durable publisher response is to move the parts of the transaction Apple can see onto infrastructure the publisher owns.

Sell-side read

Publishers that run their own server-side ad infrastructure keep bid density and first-party signal in environments that increasingly punish third-party calls, while those dependent on blocked vendors take a silent revenue hit on iPhone and iPad traffic.

Watch

Whether iOS 27.2 ships The Trade Desk's fix to the general install base, and whether the wider WebKit blocklist expands past the identity vendors named so far.