What is the ab cookie?
Serves as a unique pseudonymous identifier used by TransUnion (formerly Neustar / Aggregate Knowledge) to synchronize identities and build consumer profiles for targeted advertising.
Table of Contents
About ab
| Vendor | TransUnion |
|---|---|
| Cookie Domain | agkn.com |
| Category Category The functional category of the technology, such as Web Analytics or Social Media. Learn more | Data Management (DMP) |
| 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 15.2% of scanned pages |
| Expiration Type | Timestamp |
| Expiration Duration | 1 yr |
| 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.transunion.com/privacy/neustar |
| Vendor Website | https://www.transunion.com/ |
What is the purpose of ab?
The ab cookie is a persistent third-party identifier set by the agkn.com domain, which originally belonged to Aggregate Knowledge - a Data Management Platform (DMP) acquired by Neustar in 2013 and subsequently by TransUnion in 2021. It assigns a unique ID to a site visitor's device. This ID is used to synchronize user identities across the programmatic advertising ecosystem and various partner networks (as reflected by the cookie-sync and pixel initiators on the aa.agkn.com and d.agkn.com hosts). By doing so, the platform can aggregate cross-site browsing behavior, segment audiences, and perform identity resolution and audience modeling to deliver targeted digital advertising.
What are the Privacy Risks of ab?
Risk Level: High
The ab cookie poses a high privacy risk because it is set by a third-party data broker (TransUnion/Neustar) to facilitate cross-site tracking and identity resolution. It supports monitoring of user behavior across independent websites and the building of behavioral/identity profiles that are synchronized and shared with various advertising platforms and partners for targeted marketing and audience modeling purposes. This cross-domain data sharing with a data broker elevates the risk beyond ordinary pseudonymous analytics.
How to Remove ab from a Website
To remove the ab cookie, a website administrator must locate and eliminate the TransUnion/Neustar Aggregate Knowledge tracking tags or pixels (e.g., calls to aa.agkn.com and d.agkn.com) from the website's source code or tag management system. If the agkn.com network calls are triggered dynamically by an integrated partner (such as an ad exchange, demand-side platform, or CDP syncing audience IDs), the administrator must configure that partner platform's settings to disable identity syncing or audience sharing with TransUnion. If the site deliberately relies on TransUnion's DMP/identity-resolution capabilities for audience segmentation, the cookie cannot be removed without fully disabling those features or removing the vendor's service.