Apple's Safari blocklist pushes publishers back to Trusted Server

Apple's latest software update started blocking tracking companies inside Safari without warning, and the effect landed hardest on publishers' most valuable traffic. Safari is the default browser on every iPhone and iPad, so when a vendor a publisher depends on to sort readers into advertisable groups disappears from Safari, bids on that traffic drop. The immediate reflex has been to a fix publishers had long shelved: IAB Tech Lab's Trusted Server, which moves ad requests, auction logic and creative delivery off the reader's device and onto servers the publisher controls, so Apple cannot see or block the connection. "Certainly, in this week, we've seen a big influx of publishers reaching out to get a better understanding of Trusted Server and or committing to deploying it to test," said Rowena Lam, senior director of privacy and data at IAB Tech Lab and the product lead, who declined to give a number. Paradium, which owns Men's Journal and Parade, had a head start after helping develop it and is now re-pointing its Permutive code through Trusted Server for Safari. "In practice, that should help some signals much more than others, such as ID longevity, ad-block resilience, and clean auction data. Viewability, verification, and getting buyers to accept our numbers are where most of the work remains," said Stephanie Mazzamaro, head of revenue and data at Paradium.AI. The catch is explicit: the fix costs engineers, and prior attempts to run auctions server-side earned publishers less because buyers lost the cookies they used to recognise readers. Aditude's Justin Wohl, who also consults for Salon, called it "a defining moment and a moment of reckoning; those in control of the operating system have great control and great potential to vertically integrate for their own advantage and profit." That concern is sharpened by Apple's own ad business, whose Services division hit a record $30.7 billion in the June quarter.

The crux

Apple can update an unpublished blocklist whenever it likes, so every vendor a publisher relies on is now one silent change from going dark, and the only durable answer is to stop depending on the device to run the auction.

Sell-side read

Publishers who have been treating Trusted Server as a someday project now face a real deadline, and the trade-off is explicit: you gain signal durability and you lose the cookie-based bidding uplift buyers already pay for. Price the migration against the traffic you cannot monetise in Safari today, not against the revenue you had in 2023.

Watch

whether IAB Tech Lab's first production publisher reports results in the next quarter, and whether Apple extends the list beyond the largest vendors to the mid-tier companies most publishers actually run.