What is the _pk_ses.* cookie?
Shows the visitor’s active session. If the cookie doesn’t exist, it means that the session ended more than 30 minutes ago and was counted in the _pk_id cookie.
Our October 2026 scan found it on 25 sites (1% of the 2,450 we scanned), set before any consent.
- Purpose
- Analytics
- Belongs to
- Piwik
- Set as
- First-party (under the site's own domain)
- Typical lifetime
- Under a day (vendor says: 30 minutes)
- Name
- A family of cookies: the part after _pk_ses. varies by site or account.
Sites that set _pk_ses.* before consent
The highest-ranked 25 of 25 sites.
- europa.eu0 tracking companies
- openstreetmap.org0 tracking companies
- rfc-editor.org0 tracking companies
- admin.ch1 tracking company
- inps.it1 tracking company
- rakuten-sec.co.jp5 tracking companies
- meteociel.fr1 tracking company
- enable-javascript.com1 tracking company
- dantri.com.vn4 tracking companies
- inmotionhosting.com4 tracking companies
Show 15 more sites
- ria.ru4 tracking companies
- mpg.de0 tracking companies
- douban.com1 tracking company
- kochava.com4 tracking companies
- wipo.int2 tracking companies
- dns.com2 tracking companies
- gnome.org0 tracking companies
- unl.edu11 tracking companies
- index.hu5 tracking companies
- easydns.com3 tracking companies
- virtualmin.com0 tracking companies
- ucloud.cn3 tracking companies
- caissedesdepots.fr0 tracking companies
- uni-lj.si1 tracking company
- 1984.is0 tracking companies
How to stop it
Declining non-essential cookies in a site's consent banner should stop _pk_ses.* 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.