What is the KP_UIDz-ssn cookie?
We don't have a vendor description for this cookie yet, but our scan shows it's set by a third-party domain we haven't identified, and it typically lasts 1 day. It's listed as unclassified.
Our October 2026 scan found it on 6 sites (0% of the 2,450 we scanned), set before any consent.
- Purpose
- Unclassified
- Set as
- First-party on 83% of sites, third-party on 17%
- Typical lifetime
- 1 day
Sites that set KP_UIDz-ssn before consent
The highest-ranked 6 of 6 sites.
How to stop it
Declining non-essential cookies in a site's consent banner should stop KP_UIDz-ssn 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.
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.