What is the oo cookie?
„oo” is an HTTP cookie set by the .facebook.com domain. It typically appears when a visitor interacts directly with Facebook (logging in, visiting a facebook.com page) or when a third-party site loads Facebook elements such as „Like”/„Share” buttons, embedded videos, or social plugins.
It is not generated by the host site itself, but by Facebook's infrastructure running within that page's context.
What data it stores
The value of this cookie essentially reflects the user's opt-out status — whether they have disabled Facebook cookies or declined tracking by the platform. It does not contain direct identifiers (name, email) and is not used for advertising profiling.
Its data is sent to Facebook's servers (the .facebook.com domain), not to the site hosting the social element.
What it is used for
For Facebook, „oo” acts as an internal technical signal: it lets the platform recognize that a given visitor has opted out of tracking, so that other Facebook cookies or scripts respect this preference when social features appear on other websites.
For the host site embedding a Facebook plugin, this cookie serves no purpose of its own — it's a side effect of loading that social component.
Does it require consent?
In CookieFix's classification, „oo” is marked as strictly necessary, since it doesn't track browsing behavior but only stores a technical opt-out preference. Strictly necessary cookies don't require prior consent under Article 5(3) of the ePrivacy Directive (transposed in Romania via Law 506/2004), but they must still be disclosed in the site's cookie policy.
Site owners should nonetheless verify the exact context: if the Facebook element generating this cookie also loads other marketing cookies (such as „fr” or those from Facebook Pixel), those require separate consent via a banner before loading.
How to block or delete oo
Visitors can delete or block this cookie through their browser's cookie management settings for facebook.com, or by enabling third-party cookie blocking. Logging out of Facebook and using private browsing also reduce its occurrence.
- Chrome/Edge/Firefox: Settings → Privacy → Cookies → search „facebook.com” → delete
- Enable „Block third-party cookies” to prevent it being set via other sites
For site administrators, a consent management platform (CMP) like CookieFix can automatically block the Facebook scripts and elements that trigger this cookie until the visitor makes a choice through the consent banner.
Frequently asked questions
It's an HTTP cookie set by the .facebook.com domain that stores whether the user has opted out of tracking or disabled Facebook cookies.
No, it's classified as strictly necessary since it doesn't track browsing behavior, but it should still be listed in the site's cookie policy.
It typically lasts 5 years from the time it's set, according to publicly documented Facebook cookie information.
You can delete it from your browser's privacy settings by searching for cookies belonging to facebook.com, or prevent it via third-party cookie blocking.