What is the MR cookie?
Stores a binary flag indicating whether to refresh or reset the MUID cookie, which is used for Microsoft analytics and targeted advertising.
Table of Contents
About the MR cookie
| Vendor | Microsoft |
|---|---|
| Cookie Domain | bing.com,clarity.ms,microsoft.com,msn.com,office.com |
| Category Category The functional category of the technology, such as Web Analytics or Social Media. Learn more | Social 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 27.2% of scanned pages |
| Expiration Type | Timestamp |
| Expiration Duration | 7 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://privacy.microsoft.com/en-us/privacystatement |
| Vendor Website | https://www.microsoft.com/ |
What is the purpose of the MR cookie?
The MR cookie is a third-party tracker set by Microsoft services, including Universal Event Tracking (UET) for Bing Ads and Microsoft Clarity. It contains a binary flag (typically '0') that indicates whether the browser's MUID cookie should be reset or refreshed. The MUID cookie itself acts as a unique device identifier used for site analytics, behavioral profiling, and cross-site targeted advertising across Microsoft domains. By managing the lifespan and synchronization of the MUID cookie, the MR cookie ensures persistent and accurate tracking of users across multiple sessions and websites.
What are the Privacy Risks of the MR cookie?
Risk Level: Medium
The MR cookie is associated with Microsoft tracking services such as Bing Ads (Microsoft Advertising) and Microsoft Clarity. The cookie itself only stores a binary flag (typically '0') and does not directly carry Personally Identifiable Information (PII). Its role is to help persist and refresh the MUID identifier, which Microsoft documents as a pseudonymous, non-personally-identifiable browser identifier used for cross-site behavioral profiling, analytics, and targeted advertising. Because the technology enables pseudonymous cross-site tracking and profiling rather than sharing PII with third parties, the risk level is assessed as Medium.
How to Remove the MR cookie from a Website
To remove this cookie, website administrators must completely disable or remove the Microsoft tracking scripts that initiate it, such as the Bing Universal Event Tracking (UET) tag or the Microsoft Clarity script. Because this cookie is set in a third-party context by Microsoft servers (such as bat.bing.com or c.clarity.ms), simply modifying script parameters may not prevent it from dropping. The only guaranteed method for removal is to remove the vendor's service from the website entirely.