What is the XANDR_PANID cookie?
This cookie is set by Microsoft's Xandr advertising platform to uniquely identify visitors across websites and optimize the relevance of programmatic advertisements.
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About XANDR_PANID
| Vendor | Microsoft |
|---|---|
| Cookie Domain | adnxs.com |
| Category Category The functional category of the technology, such as Web Analytics or Social Media. Learn more | Web Analytics |
| 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 18.2% of scanned pages |
| Expiration Type | Timestamp |
| Expiration Duration | 29 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 | Medium |
| Vendor Privacy Policy | https://help.ads.microsoft.com/#apex/ads/en/ext60205 |
| Vendor Website | https://www.microsoft.com |
What is the purpose of XANDR_PANID?
The XANDR_PANID cookie is deployed by the Xandr advertising platform, which was originally AppNexus and was acquired by Microsoft in 2022. It contains a randomly generated unique identifier that enables the platform to distinguish individual browsers and devices as users navigate across different websites.
The data stored in this identifier allows advertisers to track browsing behavior, build interest profiles, measure the effectiveness of programmatic ad campaigns, and deliver highly targeted advertisements across the Microsoft Advertising ecosystem. By syncing this identifier across domains, the platform can effectively implement frequency capping and cross-site behavioral targeting.
What are the Privacy Risks of XANDR_PANID?
Risk Level: Medium
The XANDR_PANID cookie carries a Medium risk level because it functions as a persistent, cross-site tracking identifier used for behavioral profiling and targeted advertising. While it does not inherently transmit raw Personally Identifiable Information (PII) directly within the cookie payload, it enables a third-party advertising network to construct extensive pseudonymous user browsing histories across the web.
How to Remove XANDR_PANID from a Website
To remove the XANDR_PANID cookie, website administrators must disable or remove any Xandr, AppNexus, or Microsoft Advertising tags, pixels, or prebid header bidding integrations from their website's source code or tag management system. Because this identifier is core to the ad-tech platform's tracking and delivery mechanisms, it cannot be selectively disabled while maintaining the advertising functionality. If the technology is required for advertising revenue or tracking, it cannot be removed without disabling the associated ad delivery services entirely.