Xandr Cookie Matching Service (formerly AppNexus) enables a buyer to associate the cookie that identifies a Tealium visitor and the cookie that identifies the user for Xandr. This article describes how to set up the Xandr Cookie Matching Service tag in your Tealium iQ Tag Management account.

In this article:

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Tag Tips

  • This tag will only fire once per Tealium Visit Session.
  • Sends the following server-side attribute back to Tealium:
    • adnxs_uid
  • If left blank, Tealium Account and Tealium Profile is automatically populated.

Tag Configuration

First, go to the Tealium tag marketplace and add the Xandr Cookie Matching Service tag. (Learn more)

After adding the tag, configure the following settings:

  • Tealium Account
  • Tealium Profile

Data Mappings

Mapping is the process of sending data from a data layer variable to the corresponding destination variable of the vendor tag. For instructions on how to map a variable to a tag destination, see Data Mappings.

The available categories are:


Variable Description


Tealium Account


Tealium Profile