What is the OptanonConsent cookie?
OptanonConsent is the main state cookie used by OneTrust, one of the most widely used consent management platforms (CMPs) internationally. It is set automatically by the OneTrust script on any website that uses this CMP to power its cookie banner.
The cookie appears as soon as a visitor interacts with the banner — whether they click "Accept All," "Reject," or customize preferences by category. It is specific to OneTrust's technology and unrelated to other CMP platforms.
What data it stores
OptanonConsent stores a set of technical parameters describing the consent decision: a banner configuration identifier, the date and time of consent, the cookie categories accepted or rejected (typically encoded as groups such as C0001, C0002, etc.), and sometimes the version of the privacy policy accepted. The exact value format can vary depending on each site's OneTrust configuration.
The data generally stays in the visitor's browser and is read locally by the OneTrust script to decide which other cookies can be activated on the page.
What it is used for
The cookie's purpose is strictly functional: it lets the site "remember" the visitor's consent choice so the cookie banner doesn't reappear on every page or visit. Without it, any CMP would need to request consent repeatedly, harming the user experience.
For the site administrator, this cookie is the technical mechanism that can, if needed, demonstrate that a visitor made a specific choice on a specific date.
Does it require consent?
OptanonConsent is classified as strictly necessary, since it exists solely to record consent — it does not track visitors for marketing or statistical purposes.
- Under GDPR and the ePrivacy Directive (transposed in Romania via Law 506/2004), strictly necessary cookies do not require prior consent.
- The site owner must still disclose it in the cookie policy, along with its purpose and duration.
- If a site uses OneTrust as its CMP, this cookie is a natural part of the platform's operation; no additional action is needed for it specifically.
How to block or delete OptanonConsent
A visitor can delete or block OptanonConsent from their browser settings (Chrome, Firefox, Edge, and Safari all allow deleting individual cookies or blocking a domain entirely). The practical effect is that the consent banner will reappear on the next visit, since the site no longer "knows" the previous choice.
For site owners who don't use OneTrust but want an equivalent consent mechanism for their own cookies (statistics, marketing, preferences), a CMP like CookieFix can automatically block third-party scripts until the visitor makes a choice, preventing premature activation of cookies that require consent.
Frequently asked questions
No. It is a strictly functional cookie that only stores the visitor's consent choices, with no marketing or analytics purpose.
No, since it's strictly necessary for the consent banner to function, but it must still be listed in the site's cookie policy.
Typically around 1 year, after which the stored consent expires and the banner may reappear.
The site no longer remembers the previous choice, and the OneTrust consent banner will show again on the next visit.