What is the OptanonAlertBoxClosed cookie?
OptanonAlertBoxClosed is an HTTP cookie set by OneTrust, one of the most widely used consent management platform (CMP) providers worldwide. It appears on a site as soon as a visitor interacts with the OneTrust cookie banner — for example by accepting, rejecting, or simply closing it.
It is specific to sites running the OneTrust consent solution, not a cookie found across the web generally. If a site uses a different consent platform, this cookie will not be present.
What data it stores
The cookie stores the date and time the visitor closed or responded to the consent banner, typically as a timestamped date value. It does not contain directly identifying information such as a name or email address.
The value is read locally by the OneTrust script running on the site and is not normally sent to separate third-party servers — its role is to tell the banner whether it needs to be shown again to that visitor.
What it is used for
The cookie's purpose is purely functional: it tells the consent system that the user has already seen the banner, so it is not displayed repeatedly on every page load. Without it, visitors would see the cookie banner on every visit, harming the browsing experience.
For a site owner, this cookie is part of the technical infrastructure required for the consent solution to work correctly and to honor the visitor's choice for the duration of the cookie's lifetime.
Does it require consent?
OptanonAlertBoxClosed is classified, consistent with OneTrust's own practice and most CMPs, as a strictly necessary cookie. Strictly necessary cookies do not require prior visitor consent under Article 5(3) of the ePrivacy Directive (implemented in Romania via Law 506/2004), since they are essential to the operation of the consent mechanism itself.
Even though acceptance is not required, site owners must still disclose it in their cookie policy, along with its purpose and duration, for transparency under the GDPR (Regulation 2016/679).
How to block or delete OptanonAlertBoxClosed
A visitor can delete or block this cookie from browser settings (Chrome, Firefox, Edge, Safari), under the cookie and site data management section. Blocking it will cause the OneTrust banner to reappear on every visit, since the system can no longer remember the earlier choice.
For site owners using a different consent platform, such as CookieFix, handling of this kind of strictly necessary cookie is automatic — non-essential scripts stay blocked until consent is given, while strictly necessary cookies like this one are allowed by default and listed in the automatically generated cookie policy.
Frequently asked questions
No. It is a strictly necessary cookie used to run the OneTrust consent banner, so it falls outside the prior-consent requirement of the ePrivacy Directive.
The OneTrust cookie banner will reappear on your next visit, since the system no longer knows you already closed or responded to it.
It is set by the OneTrust script, when the site you're visiting uses this consent management platform to handle cookies.
The typical duration is 1 year, though this can vary depending on each site's specific configuration.