Earlier this week, Google rolled out an update to Chrome for iOS that disabled several minor browser features, including DNT. Mozilla’s Firefox for iOS also doesn’t offer the anti-tracking feature.
You may not see the change right away, as Google says it is rolling out the update to iOS users gradually. In addition to DNT, the new version of Chrome disables Data Saver, in-browser Cookie settings, auto-detect encoding, and enterprise support.
The reason for the change is that Chrome recently switched over to Apple’s WKWebView API, which is only available in iOS 8 and up. Google decided to use the API, which was introduced in 2014 alongside iOS 8, because it puts third-party browsers on par with Safari. Previously, third-party browsers were forced to use an older, slower-rendering engine than Safari’s current one—putting alternative browsers at a disadvantage. Apple doesn’t allow third-party browsers to run their own rendering engines on iOS.
The story behind the story: It may sound like Google decided to sacrifice privacy in the name of speed and stability for its iOS users, but there’s far more to it than that. DNT was poorly implemented from the outset and there’s little reason to support it. DNT is essentially a message to advertisers that says “please don’t track this browser.” But advertisers are free to disregard this request, and many do. It is so useless that major sites like Yahoo decided to ignore it too. Most browser makers don’t even turn it on by default and bury it in the browser settings. For PC and Mac users, a far better option is to use aggressive anti-tracking browser extensions such as the Electronic Frontier Foundation’s Privacy Badger.
Although Safari uses the same essential underpinnings as Chrome on iOS, Apple has special advantages when it comes to using its own technology. Safari, unlike Chrome and Firefox, is able to make changes to the header request sent to websites by the browser, as first reported by Motherboard. This is the essential point when a DNT request is sent. Without the ability to modify the header, a DNT request can’t happen.
If you really want to avoid tracking on iOS but don't want to use Safari, your best option is to use an incognito window in Chrome. You’ll still be tracked, but only for that session, rendering the tracking relatively useless.
Otherwise, you can use the DNT feature in Safari. A better option for Safari, however, is to look at the new content blockers. These apps block ads on Apple’s browser and can prevent advertisers from trailing you across the web as you hop from site to site.