Apple finally explains its Safari block, and identity companies are the target

A month after Apple started cutting off companies that follow people around the web in Safari, its engineers laid out the reasoning in a WebKit blog post. The mechanism Apple is attacking is email-based identity resolution: when someone types an email address into a site, a company working with that site can convert it into an ID that lets advertisers recognise the same person across sites without cookies. LiveRamp, ID5 and The Trade Desk's UID 2.0 all work this way, along with Permutive and Audigent, and all were among the first cut off in September. Apple's argument, as Digiday's Seb Joseph and Krystal Scanlon report, is that email has replaced the cookie as the tracking hinge, and because people keep one address for years across every device, the tracking is "far harder to shake than a cookie ever was". The block extends to Macs and Vision Pro, and it shuts out a target's entire web address, so fiddling with how a request is built won't sneak through. The piece's unanswered questions are the real caveat: Apple names no companies, explains no route on or off the list, and has already caught at least one by mistake, The Trade Desk's ad server, which was blocked alongside UID 2.0 in the first days and has since been switched back on. A publisher-side ad tech exec told Digiday the core problem plainly: "The question is who gets to decide what privacy-preserving advertising looks like. Apple controls the operating system, the browser engine and increasingly the technical infrastructure through which advertising reaches the user. If Apple can decide which ad-tech companies are technically allowed to communicate with Safari, it is effectively making market-access decisions." Apple's track record invites suspicion: after 2021's App Tracking Transparency, Apple's share of the iPhone app-install ad market went from 17% to 58%, and it is now hiring into 86 Apple Ads roles, including a "Signals Intelligence" team.

The crux

Apple is using the browser to decide which identity vendors may exist in its ecosystem, and it is doing so at the exact moment its own ads business is expanding, leaving publishers to rely on an identity layer controlled by a company that is also a growing competitor.

Sell-side read

Every publisher running LiveRamp, ID5, UID 2.0 or an email-derived ID on Safari inventory is losing addressability and therefore yield on Apple devices, which is a reason to accelerate first-party authentication and login-wall strategies, not to keep betting on third-party ID graphs Apple can cut off by fiat.

Watch

whether Apple extends the blocklist beyond the first handful of vendors, and whether the Trade Desk's accidental ad-server block becomes a pattern of over-blocking.