Apple’s Safari ad tech blocklist sends publishers back to IAB Tech Lab’s Trusted Server

That leaves publishers looking again at a fix they’d long put off: running their own ad infrastructure through IAB Tech Lab’s Trusted Server. Right now, when someone opens a news site in the Safari browser on an iPhone or iPad, the device doesn’t just load the article. It also contacts dozens of ad tech companies directly, sharing data about the reader and asking advertisers to bid on the ad space. Safari can see those contacts and it blocks any company on Apple’s list. Trusted Server takes the device out of that loop by moving the ad process off the reader’s phone or tablet and onto servers the publisher controls. Apple can’t stop what it can’t see. Its only option would be to block the news site itself, which would break the site for every Safari user.

“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, who is also the product lead for Trusted Server.

She declined to put a number on it but said Tech Lab is getting ready to go live with its first publisher, with results to share soon. Indeed, interest had been building for about a year among more forward-thinking publishers, Lam said, and what’s transpired over the past week has sent it up sharply. 

Take Paradium, which owns Men’s Journal and Parade. It relies on Permutive, one of the companies on Apple’s blocklist, to sort its readers into groups advertisers want to reach. That stopped working on Safari after Apple blocked certain ad tech vendors. In response, Paradium’s team updated the Permutive code on the publisher’s pages to run through Trusted Server and is now testing the setup, watching to see whether audience data starts flowing again. 

Unlike other publishers, Paradium had a head start, having been an early adopter of Trusted Server and helped develop it over the past year. That period of testing has left it with a clear view of the trade-offs.

“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, which rebranded from Arena Media Group in August. 

Others are further behind, though Apple’s block has them paying attention.

“We are aware of the Trusted Server initiative but haven’t really dug deep into it yet. However, perhaps we should start doing that,” said the ad tech lead at a publisher, who asked to remain anonymous so as not to draw the ire of Apple. 

The bigger picture

Trusted Server is one route but it isn’t the only one. For example, Aditude, which helps publishers sell their ad space, offers its own Prebid Server, which vp Justin Wohl said can process ad requests outside the browser and connect via APIs to identity providers such as ID5, UID2 and LiveRamp. The aim is to improve addressability when browser-based scripts or domains are blocked.  Still, Trusted Server is the one publishers keep coming back to since its open source, owned by no single company and puts them in charge of who gets the data. 

That they’re even considering it all says plenty. They’ve known about Trusted Server since IAB Tech Lab unveiled it in March 2025, and few did anything about it. Tech Lab pitched it as a way for publishers to take more control of their advertising and make their pages load faster since a phone that only has to talk to the news site, while Trusted Server handles the ad tech companies behind the scenes, is quicker than one talking to dozens of them all at once.

Both were hard benefits to put a price on, while the cost was easy to see. Publishers would need engineers to run servers their ad sales teams had never had to deal with. Moreover, the software was still close to a prototype. On top of that, plenty of publishers had already tried running their ad auctions on their own servers instead of in readers’ browsers. When they did, they earned less because advertisers lost access to the cookies they used to recognise readers and bid lower without them. Most weren’t in a hurry to try again.

Apple changed that. Safari, while nowhere near the size of Chrome, is the default browser on every iPhone and iPad. That makes it the main way a big share of readers across the Atlantic get news on their devices. They also tend to be the readers advertisers pay most to reach, so losing the ability to track them in the Safari browser hits publishers’ most valuable traffic first. The bigger worry is what comes next. Once Apple can update its list whenever it likes, every vendor a publisher relies on is one change from going dark. 

“The concern for me is that we observed an industry impact coming not from a browser change but an operating system change,” said Wohl, who is also a consultant for news publisher Salon. “It’s 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. The same could happen with Google x Android at any point.” 

Whatever they do next, publishers have been reminded by events over the last week that Apple’s stance on privacy is a shield and a sword for advertising. It shields its device owners from the companies that follow them around the web and it cuts those same companies down just as Apple’s own ad business starts to grow. Apple rebranded Search Ads as Apple Ads last year, packed more ad slots into App Store search results this spring and has started selling ads in Maps. Not to mention its broader Services division, which houses its advertising business, reached an all-time record of $30.7 billion in revenue for the June quarter. Every vendor that goes dark on an Apple device leaves a little more room for the one company that controls the list. 

“Our concern with the iOS 27 change is less about any single vendor and more about how it was done,” said Mazzamaro. “Safari now blocks certain companies outright based on a list Apple hasn’t published, with no notice to the businesses affected and no clear way to appeal. The industry learned about it from broken ad delivery after launch, not from Apple,” she said. 

In other words, it’s a market power issue.