What is the uuid cookie?
Collects data on the user's visits to the website, such as what pages have been loaded. The registered data is used for targeted ads.
Our October 2026 scan found it on 36 sites (1% of the 2,450 we scanned), set before any consent.
- Purpose
- Advertising
- Belongs to
- Mediamath
- Set as
- First-party on 31% of sites, third-party on 69%
- Typical lifetime
- 3 months (vendor says: 1 year) — shorter than the vendor documents
- Where it's common
- 31% of the sites that set it use a .ru domain.
Sites that set uuid before consent
The highest-ranked 30 of 36 sites.
- avast.com5 tracking companies
- dell.com12 tracking companies
- amazon.co.za32 tracking companies
- ivi.ru10 tracking companies
- livejournal.com11 tracking companies
- megafon.ru5 tracking companies
- rutube.ru1 tracking company
- jstor.org2 tracking companies
- rambler.ru9 tracking companies
- ojogodobicho.com6 tracking companies
Show 20 more sites
- az24.vn22 tracking companies
- avira.com5 tracking companies
- sky.com5 tracking companies
- dantri.com.vn4 tracking companies
- mirtesen.ru4 tracking companies
- idnes.cz42 tracking companies
- ctvnews.ca38 tracking companies
- lenta.ru9 tracking companies
- gaijin.net1 tracking company
- dictionary.com35 tracking companies
- askona.ru8 tracking companies
- avg.com6 tracking companies
- pchome.com.tw6 tracking companies
- toyota.com19 tracking companies
- mk.ru6 tracking companies
- redcross.org16 tracking companies
- iu.edu15 tracking companies
- netshoes.com.br15 tracking companies
- insales.ru9 tracking companies
- talkie-ai.com0 tracking companies
How to stop it
Declining non-essential cookies in a site's consent banner should stop uuid being set on later visits. Blocking third-party cookies in your browser settings stops the third-party kind everywhere, and clearing cookies for a site removes any it already set.
Description from the Open Cookie Database (Apache 2.0).
Understanding this page
- How cookie lifetimes work, and why a 13-month _ga matters
What a cookie's "expires" field actually controls, why Google Analytics ships a 2-year default that many sites cut down to 13 months, and how Safari's 7-day cap on script-set cookies changes the picture.
- First-party vs third-party cookies (and why "first-party" still tracks you)
What the distinction actually means technically, why browsers only block one of the two, and how CNAME cloaking, server-side tagging and cookies like _ga let sites keep tracking under their own domain.
- How to block or limit trackers
Browser privacy settings, content blockers, Global Privacy Control and clearing cookies compared honestly — what each one actually stops, what it doesn't, and what it costs you in return.