Safari and WebKit in the iOS, iPadOS, macOS and visionOS 27 releases have closed network access to identity resolution infrastructure. WebKit's team said so on October 19, 2026, in the article «Blocking Identity Resolution Infrastructure».
According to WebKit, such companies collect an email address at login or newsletter signup, create a persistent tracking ID and send it back to the page. The block works at the domain level, so companies cannot get around it by changing the structure of their requests. The publication names no companies. The affected services include The Trade Desk and ID5.
The ad tech response comes down to moving calls from the browser to the server. IAB Tech Lab is promoting Trusted Server for this: an open framework that handles ad requests, auctions and creative delivery on the publisher's side. It integrates with Prebid Server, and publishers can already test and deploy it.
At the same time, a court ruling on Google is affecting the market. On September 2, Judge Leonie Brinkema refused to force Google to sell the AdX exchange and chose behavioral remedies instead. The full text of the ruling was published on September 16.
The ruling requires Google to connect AdX and DFP to Prebid. AdX must also take part in bidding from competitors' ad servers on the same terms as DFP. The term is six years.
The difference between the two scenarios lies in where the request originates. WebKit describes the block as network access from Safari and WebKit, and the publication does not make clear whether it affects server-side calls. Apple did not answer that question in the text. Apple maintains the domain list itself and can expand it without releasing a new version of iOS.
