First-Party Data

Get answers about first party data. Understand the key concepts and how they apply to your conversion tracking setup for optimal performance and tracking accuracy.

First-party and third-party cookies are set to track user behavior. They serve similar purposes but are set, collected, and blocked in different ways.

First-Party Cookies

First-party cookies are set by the website you visit. They enable website owners to collect analytics data, remember user settings, and improve user experience.

When a user signs into Amazon, the browser requests the user’s identity. The browser stores this cookie under the “amazon.com” domain. Without first-party cookies, users would need to sign in every time they visited, and shopping carts would reset after each item.

Third-Party Cookies

Third-party cookies are created by domains you are not visiting. They are placed on websites through ad platform scripts and tags. Third-party cookies are accessible on any website that loads the third-party server’s code.

When browsing Amazon, a user views shoes they don’t purchase. Later, they see ads for those same shoes on other websites. This is third-party cookie tracking—the data persists even after closing the browser.

Key Differences

Aspect	First-party	Third-party
Set by	Publisher’s server or website JavaScript	Third-party `API` or ad platform code
Availability	Only on the originating domain	On any website loading the third-party code
Browser support	All browsers; user can delete	Most browsers; blocked by default

AnyTrack Cookies

AnyTrack sets these first-party cookies on your domain:

Identifier	Example value	Description
`_atcid`	`GLmcNJl0CpDkxl`	Client ID: a unique anonymous identifier set on the visitor’s browser. The cookie has a two-year lifetime. AnyTrack uses it to track the visitor’s actions and sessions and to attribute them to campaigns and conversions. AnyTrack also saves the Client ID server-side, so it restores the identity when a browser caps the cookie (for example, Safari ITP) or the visitor deletes it.
`_atcid-pt`	`1677855987888`	Timestamp of the session
`_atutm`	campaign parameters	Stores the last campaign parameter the visitor came from