What is the demdex cookie?
Assigns a unique identifier to a site visitor to support cross-domain tracking, visitor identification, audience segmentation, and ID synchronization within the Adobe Experience Cloud.
Table of Contents
About the demdex cookie
| Vendor | Adobe |
|---|---|
| Cookie Domain | demdex.net |
| Category Category The functional category of the technology, such as Web Analytics or Social Media. Learn more | Advertising & Paid Media |
| Consent Category Consent Category The consent category this cookie most commonly falls under across sites we scan, normalized into four standard categories. Learn more | Targeting & Advertising |
| Prevalence | Very Common |
| Popularity Popularity Popularity is calculated from our dataset of 4.5B+ cookies analyzed across hundreds of millions of web pages. Learn more | Found on 32.3% of scanned pages |
| Expiration Type | Timestamp |
| Expiration Duration | 27 days |
| Party Type Party Type Whether the cookie is first-party or third-party. Learn more | 3rd-Party |
| Risk Level Risk Level Rates how sensitive the data stored by this cookie is (High, Medium, or Low) based on data classification and distribution. Learn more | High |
| Vendor Privacy Policy | https://www.adobe.com/privacy/policy.html |
| Vendor Website | https://www.adobe.com |
What is the purpose of the demdex cookie?
The demdex cookie is a persistent, third-party tracking identifier set by Adobe Audience Manager and the Adobe Experience Cloud Identity Service. It contains a Unique User ID (UUID), also known as the demdex ID. This cookie is set on the legacy demdex.net domain (Demdex was acquired by Adobe in 2011), allowing the identifier to persist across multiple independent websites and track user navigation across any domain that utilizes Adobe Experience Cloud solutions.
When combined with a customer's organization ID, the demdex ID is mathematically used to generate a consistent first-party Experience Cloud ID (MID). This mechanism enables critical functions such as ID synchronization with third-party advertising partners (like Demand Side Platforms), cross-domain audience segmentation, algorithmic look-alike modeling, and centralized behavioral reporting.
What are the Privacy Risks of the demdex cookie?
Risk Level: High
The demdex cookie assigns a persistent, third-party unique identifier used specifically for cross-site tracking, audience segmentation, and ID synchronization with external platforms (such as DSPs and other advertising partners). Because it operates on a third-party domain (demdex.net) and is explicitly designed to track user behavior across multiple independent websites to build comprehensive advertising profiles, it presents a High privacy risk.
How to Remove the demdex cookie from a Website
To remove this cookie, site administrators must modify the configuration of the Adobe Experience Cloud Identity Service or Adobe Audience Manager tags. Specifically, administrators can set disableThirdPartyCookies: true in the ID service configuration, which prevents the generation and use of the third-party demdex cookie while forcing the system to rely solely on first-party IDs. If the Adobe audience features are no longer required, administrators can remove the Adobe Audience Manager or Adobe Experience Platform Data Collection tags entirely from the website's source code or tag management system.
This definition was last reviewed on August 19, 2026. ObservePoint regularly reviews these definitions to ensure our customers have the most up to date information about the cookies on their websites.