What is the _px3 cookie?
One of PerimeterX's (HUMAN Security) bot-detection cookies, used together with its visitor identifier to score the legitimacy of a session.
Our October 2026 scan found it on 15 sites (1% of the 2,450 we scanned), set before any consent.
- Purpose
- Necessary
- Belongs to
- HUMAN Security (PerimeterX)
- Set as
- First-party on 93% of sites, third-party on 7%
- Typical lifetime
- Under a day
Sites that set _px3 before consent
The highest-ranked 15 of 15 sites.
- linkedin.com0 tracking companies
- roblox.com0 tracking companies
- walmart.com2 tracking companies
- target.com5 tracking companies
- zillow.com4 tracking companies
- fiverr.com7 tracking companies
- change.org6 tracking companies
- netgear.com3 tracking companies
- wayfair.com2 tracking companies
- ti.com1 tracking company
Show 5 more sites
- samsclub.com2 tracking companies
- seekingalpha.com0 tracking companies
- iherb.com3 tracking companies
- skyscanner.net2 tracking companies
- zoominfo.com4 tracking companies
Related cookies
Other cookies from HUMAN Security (PerimeterX).
How to stop it
Declining non-essential cookies in a site's consent banner should stop optional cookies, though a necessary cookie like this one may still be set. 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 written by CookieTosser, for a cookie the Open Cookie Database doesn't cover.
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.