The news: Apple is once again cracking down on third-party tracking inside its ecosystem, impeding advertisers’ ability to measure campaigns that run through Safari.

The new effort began when Apple rolled out iOS 27 last month, which restricted several identity providers, including The Trade Desk and LiveRamp, from using their tools in Safari. The Trade Desk was also blocked entirely from serving ads, but Apple said that was inadvertent and has since resolved the problem.

Apple is now compiling a larger list of ad tech vendors that could soon be restricted within Safari, spanning hundreds of demand-side platforms (DSPs), supply-side platforms (SSPs), identity providers, and other companies, per AdExchanger. The list can be amended dynamically, so Apple can feasibly add more companies without having to wait for the next iOS update.

Why this matters: The crackdown threatens to upend how advertisers use Safari for cross-channel attribution. Safari may be a far less dominant web browser than Google Chrome—it holds a 15.7% market share of global internet traffic, per StatCounter—yet it plays an important role for connecting identities across disparate advertising destinations to form a holistic picture of a customer journey.

Apple has signaled for years that it doesn’t want this process, called fingerprinting, to occur in its ecosystem. Now it’s poised to enforce the ban by blocking scores of ad tech companies that facilitate the practice. Without these tracking partners, advertisers will be unable to trace customer journeys through Safari and will have a harder time judging the performance of their ads on the browser.

Implications for advertisers: Prepare for a new period of uncertainty around campaign performance on Apple devices. Ad tech vendors may need to change how they conduct cross-channel attribution, so press partners for clarity on updates as they’re implemented. Consider reducing spend in Apple’s ecosystem until the tracking situation is resolved.

The crackdown jump-starts a new era of Apple fortifying its walled garden. First-party alternatives like server-side tracking will be imperative. If the limitations of these alternatives—such as having to deal with a patchwork of rules for different servers—are too challenging, it may be time to exit Apple’s ecosystem altogether and allocate more spend to environments that are still friendly to third-party tracking methods.

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