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A free privacy audit shows which cookies, pixels and trackers are running — and which ones commonly appear in privacy claims.
Where _uetsid tracks one visit, _uetvid tracks the visitor. It’s the long-lived ID that Microsoft Advertising’s Universal Event Tracking (UET) tag stores on your site, and it’s what lets Microsoft recognize a returning browser for conversion tracking and remarketing.
What Is the _uetvid Cookie?
Microsoft’s UET FAQ says UET “assigns this unique, pseudoanonymized visitor ID, representing a unique visitor,” and stores it in a first-party cookie named _uetvid. The same ID is sent with UET events as the vid parameter. Since July 2023, Microsoft says the cookie also holds an insights user ID, cookie version, expiry time, a consent value and the cookie’s creation time.
How Long Does _uetvid Last?
About 13 months (390 days) is what scans and Microsoft-hosted cookie tables show. Microsoft’s FAQ doesn’t state the lifetime, so treat 13 months as the commonly observed value. Safari’s tracking prevention can shorten it.
What _uetvid Makes Possible
- Conversion attribution: links a purchase or sign-up days later to the ad click that started it, along with the first-party click ID cookie
_uetmsclkid. - Remarketing lists: lets advertisers target visitors who viewed certain pages or abandoned carts.
- Audience insights: Microsoft uses cart and page data to improve targeting, according to its FAQ.
It plays a similar role to Google’s click and conversion cookies, such as _gac.
Does _uetvid Need Consent?
EU, EEA and UK
Yes. A 13-month advertising identifier is the textbook example of a cookie that needs opt-in consent. Microsoft’s guide to UET consent mode describes setting a default consent state and updating it when the visitor chooses, so UET doesn’t store cookies before consent.
US states
Remarketing with _uetvid is targeted advertising and usually “sharing” under the CCPA. Give an opt-out, honor Global Privacy Control, and stop UET for visitors who opt out, or set the _uetmsdns cookie to 1, which Microsoft says stops UET events for those visitors.
How to Block or Delete _uetvid
- Site owners: put UET behind consent and default
ad_storageto denied. Our guide to implementing cookie consent covers the setup. - Turn off cookies entirely if needed: Microsoft supports
storeConvTrackCookies:falsein the UET tag. - Update your policy: list
_uetvidwith its lifetime and purpose in your cookies policy. - Visitors: clear the site’s cookies, as our Chrome cookie removal guide shows, or use a tracker blocker.
Keeping UET Under Control
Because _uetvid lasts more than a year, one tag that fires before consent leaves an identifier sitting in the browser long after the visit. Captain Compliance’s consent banner, a cookie consent manager built for this, holds UET until visitors opt in, and our scanner checks that _uetvid doesn’t appear on first page load.
FAQ
What’s the difference between _uetvid and _uetsid?
_uetvid is a persistent visitor ID kept for about 13 months. _uetsid is a session ID kept for about a day.
Does Microsoft sell _uetvid data?
Microsoft says it doesn’t resell UET data to third parties or share it with other advertisers.
Will removing _uetvid break my site?
No. It only affects Microsoft ad measurement and remarketing.
A visitor ID that lasts more than a year means one consent mistake leaves an identifier behind for a long time. That’s the main reason UET belongs in your consent setup and not just your marketing team’s tag list.
Put this into practice
Turn privacy guidance into working controls.
Captain Compliance helps teams discover tracking technologies, enforce consent, manage privacy requests and document the evidence behind every decision.
