What is the ad-id cookie?
ad-id is an HTTP cookie set by Amazon Ads, the advertising division of Amazon, through the amazon-adsystem.com domain. It appears on a website when that site integrates an Amazon advertising module — for example Amazon DSP banners, remarketing units, or other ad formats served through the Amazon Advertising platform — or when a page loads a pixel/script tied to the Amazon ad network.
It is typically set as a third-party cookie (by the Amazon domain, not the host site directly), which classifies it as a third-party advertising cookie.
What data it stores
The cookie stores a unique identifier associated with the visitor's browser, used by Amazon to recognize that browser on subsequent visits to sites displaying ads from the Amazon Ads network. The exact value format is not publicly documented in detail and may vary.
Data collected through this identifier is sent to Amazon Ads servers (amazon-adsystem.com) and may be correlated with other advertising behavior signals Amazon collects across its partner network.
What it is used for
The main purpose is targeted advertising: Amazon uses this identifier to build interest profiles, deliver relevant ads, and measure campaign performance (impressions, clicks, conversions) on sites running Amazon Ads.
For site owners, having this cookie present enables advertising monetization or participation in Amazon remarketing campaigns, but also comes with the responsibility to declare and manage it correctly under privacy law.
Does it require consent?
ad-id is classified as a marketing/advertising cookie. Under the ePrivacy Directive (2002/58/EC) and GDPR, this type of cookie requires the visitor's explicit, prior consent before being placed in the browser.
- The site owner must list it in the cookie policy under the "marketing" category.
- The cookie must not be set before the visitor opts in to the marketing category in the consent banner.
- Refusing consent must not block access to the site's core content.
How to block or delete ad-id
A visitor can manually delete or block ad-id from their browser's cookie settings (Chrome, Firefox, Safari, Edge), either by clearing cookies for amazon-adsystem.com or by enabling blocking of third-party or ad-tracking cookies.
For site administrators, the cookie should be blocked automatically until consent is given. A CMP such as CookieFix can handle this by intercepting the Amazon Ads script and releasing it only after the visitor accepts the marketing category, preventing the cookie from being set prematurely.
Frequently asked questions
It is not malicious; it's used for targeted advertising and campaign measurement. It can, however, be considered privacy-intrusive since it tracks browsing behavior for ad profiling.
Its typical duration is 9 months from the time it's set, after which it expires automatically from the browser.
Yes, as a marketing/advertising cookie it requires the visitor's explicit consent before being placed, under GDPR and the ePrivacy Directive.
You can check via your browser's developer tools (Application/Storage tab > Cookies) or by using a cookie scanner that identifies third-party scripts, including those from amazon-adsystem.com.