What is the _vis_opt_test_cookie cookie?
This is a temporary session cookie generated to detect if the cookies are enabled on the user browser or not.
Our October 2026 scan found it on 20 sites (1% of the 2,450 we scanned), set before any consent.
- Purpose
- Functional
- Belongs to
- Visual Website Optimizer
- Set as
- First-party (under the site's own domain)
- Typical lifetime
- Session (vendor says: 100 days)
Sites that set _vis_opt_test_cookie before consent
The highest-ranked 20 of 20 sites.
- forbes.com2 tracking companies
- taboola.com4 tracking companies
- checkpoint.com4 tracking companies
- auvik.com7 tracking companies
- elmundo.es20 tracking companies
- weforum.org3 tracking companies
- suumo.jp11 tracking companies
- adroll.com11 tracking companies
- acronis.com5 tracking companies
- databricks.com4 tracking companies
Show 10 more sites
- egnyte.com3 tracking companies
- n-able.com5 tracking companies
- trimble.com6 tracking companies
- itau.com.br6 tracking companies
- straitstimes.com21 tracking companies
- netshoes.com.br15 tracking companies
- termly.io4 tracking companies
- 20min.ch5 tracking companies
- qualys.com3 tracking companies
- casasbahia.com.br8 tracking companies
How to stop it
Declining non-essential cookies in a site's consent banner should stop _vis_opt_test_cookie 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.