What is the at_check cookie?
A simple test value used to determine if a visitor supports cookies. Set each time a visitor requests a page.
Our October 2026 scan found it on 28 sites (1% of the 2,450 we scanned), set before any consent.
- Purpose
- Functional
- Belongs to
- Adobe Audience Manager
- Set as
- First-party (under the site's own domain)
- Typical lifetime
- Session (vendor says: session)
Sites that set at_check before consent
The highest-ranked 28 of 28 sites.
- avast.com5 tracking companies
- dell.com12 tracking companies
- hostgator.com3 tracking companies
- elpais.com7 tracking companies
- box.com8 tracking companies
- hbr.org12 tracking companies
- worldbank.org9 tracking companies
- lg.com2 tracking companies
- fidelity.com15 tracking companies
- ancestry.com5 tracking companies
Show 18 more sites
- as.com7 tracking companies
- canada.ca1 tracking company
- mongodb.com2 tracking companies
- avira.com5 tracking companies
- ihg.com3 tracking companies
- ford.com17 tracking companies
- aarp.org30 tracking companies
- allstate.com2 tracking companies
- mathworks.com3 tracking companies
- domain.com6 tracking companies
- pandasecurity.com3 tracking companies
- huntington.com9 tracking companies
- toyota.com19 tracking companies
- veeam.com2 tracking companies
- findlaw.com11 tracking companies
- southwest.com1 tracking company
- mheducation.com3 tracking companies
- rogers.com14 tracking companies
Related cookies
Other cookies from Adobe Audience Manager.
How to stop it
Declining non-essential cookies in a site's consent banner should stop at_check 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.