Overview

TL:DR Unless you've been using a server to extend cookie expiration, the Safari 16.4 updates will not impact you. If you have been using server set cookies, then Safari 16.4 will only impact you if the IP address of the server that's extending the cookie is materially different than the IP address of the server your site is loaded from.

How Cookies Work:

Think of cookies as miniature storage devices, utilized for various functions within the browser, such as storing your shopping cart, language preferences, and privacy settings. Unsurprisingly, cookies are also employed to retain marketing data. When you click on an ad, typically, information about the clicked ad is stored in a cookie. This saved cookie is then utilized to correlate the ad click with an event, such as a purchase. If the cookie is inaccessible at the time of purchase, the ad click won't be associated with the purchase, resulting in the purchase being unattributed on any ad platforms you may be using.

Ranking of conversion attribution: 0. Google Ads 1. Apple

Cookie Expiry

Cookies come with expiry dates, determined by various factors. Longer expirations are preferable for tracking purposes. The more prolonged we retain marketing data, the better our ability to link ad clicks to user actions on your site. For instance, with a one-day expiry (standard in Safari for ad clicks), if a user visits your site through an ad click at 9 AM on Monday morning and returns to make a purchase at 10 AM on Tuesday, the purchase will not be attributed to the ad click.

Cookie Extension in Safari 16.4

Before Safari 16.4, one workaround for extending cookies was using a method called a server-set cookie. By setting the cookie from the server, it typically had a one-year expiry, as opposed to seven days or one day in Safari/WebKit browsers. However, as of the release of version 16.4, this method of extending cookie expiry will only function if the server attempting the extension is not materially different in IP address from the server your page is loaded from. In short, if you aren't extending cookies from a server, Safari 16.4 should have no impact on your tracking.

You can learn more about the details of these changes in Simo Ahava's LinkedIn post here and by listening to a recent podcast by Elevar founder Brad Redding here.