• Sutter Mills
  • April 17, 2019
  • Blog Posts

Safari ITP 2.1: what are the consequences on the measurement of digital performance?

By Jérémie Sacilé, Consultant at Sutter Mills

In the summer of 2018, Apple unveiled an update of its Safari web browser with enhanced privacy through the “Intelligent Tracking Prevention 2.0” feature. This major update involved more restrictive management of cookies. Indeed, the lifetime of cookies was limited to 30 days. Now, Intelligent Tracking Prevention version 2.1 will reduce the lifetime of cookies to 7 days. Integration of this new feature is planned in iOS 12.2 and Safari 12.1 on macOS High Sierra and Mojave.

Just as ITP 2.0 had an impact on the measurement of advertisers’ digital performance, so too will the impacts of ITP 2.1 be even greater. As a reminder, ITP 2.0 did not allow the use of 3rd party cookies, which forced publishers in the adtech and martech market such as Google to make new measurement methods available to advertisers in order to simulate 1st party cookies. With its latest update, ITP 2.1, Apple is attacking 1st party cookies placed via client-side JavaScript by limiting their lifespan to 7 days. Session cookies will be saved to maintain the authentication of uses.

In order to visualize the impact of this restriction on cookies, let’s take a concrete example with Google Analytics.

During each visit to your website, Google’s solution deposits a cookie called “_ga” which by default has a duration of 2 years. The purpose of this cookie is to store what Google calls the “Client ID”, a unique identifier that allows the solution to link a set of visits to the same visitor. On the other hand, if a user using Safari visits your site, the lifetime of the Google Analytics cookie will be limited to 7 days.

This implies that if an Internet user is inactive for 7 days on your site, during his new visit he will be considered by the analytics solution as a new visitor. Duplication of visits may be significant if Safari represents a significant portion of your traffic and also if your sales cycle is longer than 7 days. The consequences will, therefore, have to be qualified according to the industries.

Despite some limitations, some specialists have already found workarounds. For example, we can talk about using the browser’s localStorage to store this information or using server-side techniques.

ITP 2.1 remains restrictive, concerning the global limit on 1st party cookies with regard to its initial objective which remains the prevention of cross-site tracking. However, in the face of the transformation of 3rd party cookies into 1st party cookies, as well as the failure to respect the Do Not Track functionality of the sites, this will protect the privacy of Internet users.

Not surprisingly, other browsers could potentially move towards these same limitations. Mozilla announced that it was experimentally exploring a similar approach.

We are waiting for the reaction of the publishers adtech and martech on the subject, Google has not yet communicated. Adobe states “evaluate the impact of ITP 2.1 on data collection“.



– Webkit – Intelligent Tracking Prevention 2.1

– Digiday – WTF is Apple’s latest anti-tracking update?

– Journal du Net – Apple durcit (encore) le blocage des cookies de tracking 

– Adobe – Intelligent Tracking Prevention (ITP) and Adobe Analytics

– Simo Ahava : ITP 2.1 And Web Analytics

– Tealium – Apple ITP 2.1 – What Happens Next? 

– Mozilla – Enhanced Tracking Protection Testing Update

– Mozilla – Intent to implement: Limit the maximum life-time of cookies set through document.cookie to seven days

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