Safari Intelligent Tracking Prevention

Apple Safari has an on-by-default privacy protection feature called Intelligent Tracking Protection, or ITP. ITP has been very effective in preventing cross-site tracking by disabling 3rd-party cookies completely and capping the lifetime of all script-writable website data.

By default, Fingerprint API uses 3rd party cookies (both client-side set with document.cookie and server-side set with the Set-Cookie HTTP header) and script-writable website data (localStorage) to more reliably identify returning visitors. All of these methods are affected by ITP, lowering identification accuracy.

To keep a high identification accuracy of Safari users, you need to use a Custom subdomain setup or a cloud proxy integration like Cloudflare or Cloudfront, which makes cookies set by Fingerprint considered "first-party". See Protecting the JavaScript agent from ad-blockers for more details.