What is the chk cookie?
This cookie is set on Google Chrome browsers that have a version less 67 or non-Chrome browsers, and is used for testing purposes.
Our October 2026 scan found it on 5 sites (0% of the 2,450 we scanned), set before any consent.
- Purpose
- Functional
- Belongs to
- PubMatic
- Set as
- Third-party (under another company's domain)
- Typical lifetime
- Session (vendor says: 3 months)
- Where it's common
- 100% of the sites that set it use a .ru domain.
Sites that set chk before consent
The highest-ranked 5 of 5 sites.
- ivi.ru10 tracking companies
- mirtesen.ru4 tracking companies
- askona.ru8 tracking companies
- insales.ru9 tracking companies
- iz.ru8 tracking companies
Related cookies
Other cookies from PubMatic.
- pi47 sites
- KTPCACOOKIE15 sites
- KADUSERCOOKIE14 sites
- chkChromeAb67Sec6 sites
- SyncRTB*6 sites
How to stop it
Declining non-essential cookies in a site's consent banner should stop chk 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.