First-party tracking on your own domain
Safari and Firefox block third-party cookies outright, and ITP caps the client-side ones at 7 days. Serving your tracking first-party — from your own domain — is how attribution survives it.
The tracking setup most teams still run was designed for a web that no longer exists — one where a third-party script could drop a cookie that persisted for months across sites. Intelligent tracking prevention ended that: Safari and Firefox now block third-party cookies outright, and a cookie set client-side via JavaScript can expire in as little as seven days. If your attribution window is 30 or 90 days and your cookie dies in 7, most of your funnel is invisible.
First-party vs third-party, concretely
The distinction the browser cares about is origin. A script and cookie that come from the same domain the user is visiting are first-party and get full lifetime. A script phoning home to a tracking vendor’s domain is third-party and gets throttled or blocked. Same code, wildly different survival — purely because of where it’s served from.
It’s not the tracking the browser punishes. It’s the third-party origin.
Move tracking onto your own domain
DATALYR lets you serve tracking from a subdomain of your own site — say data.yourstore.com — so dl.jsand its cookies are first-party to your visitors. The click IDs and visitor ID you capture on the landing page now persist for the full attribution window instead of evaporating after a week, and the events don’t trip the ad blockers that target known third-party tracker domains.
Concretely, first-party on your own domain gets you:
- Visitor IDs that survive ITP’s 7-day cap and third-party cookie deprecation.
- Fewer requests lost to ad blockers and tracker blocklists.
- Tracking and redirect links on your brand’s domain, not a vendor URL.
The payoff is longer memory
Attribution is only as good as how long you can remember a visitor. First-party context, a durable visitor ID, and server-side conversions are three parts of the same idea: keep the thread from click to revenue intact even as the browser tries to cut it. Get the first part right and the rest — matching orders, feeding the ad platforms — has something solid to stand on.
See how custom domains fit into a full setup in the setup guides.
