First-Party Cookie

Data & Tracking

Also: 1st Party Cookie

What it isA cookie set by the site you are visiting

Used forLogins, carts, first-party analytics

StatusStill supported across browsers

Quick definition

A first-party cookie is a small file set by the website you are actually on, under its own domain. It is how a site remembers you are logged in, keeps items in your cart between pages and powers its own analytics. Unlike third-party cookies, first-party cookies are not being phased out, which makes them the reliable foundation for measurement and personalisation as cross-site tracking declines.

Where it shows up in the data

Same-domain

A cookie is first-party when it is set by the domain you are visiting. That direct relationship is why browsers keep supporting it while restricting cross-site cookies.

Durable measurement

Because they are not blocked, first-party cookies plus server-side tracking are the reliable base for analytics and conversion measurement as third-party cookies disappear.

Personalisation and retention

First-party cookies let a site remember a returning visitor and tailor the experience, which underpins good retention and lifecycle marketing.

What it actually means

A cookie is first-party when the domain that sets it matches the site in the address bar. Your own website setting a cookie to remember a visitor's session, preferences or cart is first-party. The browser trusts these because the relationship is direct and visible, so they are not subject to the cross-site blocking that is killing third-party cookies. The strategic point is that as the industry loses cross-site tracking, first-party cookies plus data a customer gives you directly become the durable core of measurement, personalisation and retention. Server-side tracking often works by setting and reading first-party cookies to make measurement more robust.

First-party cookies are the part of tracking that still works. Build on the ground that is not shifting.

How it shows up

First-party cookies show up in your browser as cookies whose domain matches the site. They keep your login active, your cart populated and your first-party analytics counting sessions accurately even when third-party cookies are blocked.

The Australian context

For Australian businesses with heavy Safari mobile traffic, first-party cookies keep working where third-party cookies are already blocked. That makes a first-party measurement setup disproportionately valuable in the local market.

Where people get this wrong

Overlooking first-party cookies while chasing the cookieless futureThe reliable answer is often already on your own domain. Strengthening first-party cookies and data is more practical than exotic cookieless schemes for most businesses.

Assuming all cookies are being bannedOnly cross-site third-party cookies are being phased out. First-party cookies set by your own site are fully supported and safe to build on.

Not moving tracking server-sideClient-side first-party cookies can still be shortened by browser rules. Server-side tracking sets more durable first-party cookies and protects measurement quality.

Common questions

Are first-party cookies being phased out?

No. Only third-party cross-site cookies are being restricted. First-party cookies set by the site you are visiting are fully supported across browsers.

What is the difference between a first-party and third-party cookie?

A first-party cookie is set by the site you are on and handles logins, carts and its own analytics. A third-party cookie is set by another domain, usually an ad network, and tracks you across sites.

Why do first-party cookies matter more now?

As third-party cookies disappear, first-party cookies plus data customers give you directly become the durable foundation for measurement, personalisation and retention.

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About New Rebellion

New Rebellion is a marketing intelligence consultancy. We build tools, score Australian businesses on how their marketing actually performs, and publish Debrief every day. This dictionary is part of how we work in the open.

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