What is the mtm_cookie_consent cookie?
mtm_cookie_consent is created by the Matomo (formerly Piwik) tracking script when a website uses Matomo's built-in consent feature (requireConsent or rememberConsentGiven). It appears in the browser once a visitor makes a choice related to Matomo tracking, either through Matomo's own interface or via a banner or button connected to Matomo's consent API.
It is set by the Matomo instance the site owner uses (self-hosted server or Matomo Cloud), not by an external third party like Google or Meta. The domain the cookie appears on depends on how that Matomo installation is configured (its own subdomain or the site's main domain).
What data it stores
The cookie stores a simple value indicating that the visitor has expressed consent (or non-consent) for Matomo tracking, typically a yes/no-style marker without additional personal identifiers. It does not carry content data such as a name, email, or a user ID tied to other services.
The value is read locally by the Matomo script when the page loads, to decide whether statistics tracking should be activated (for example, setting another cookie such as _pk_id). It is not sent to third parties; it stays in use only by the Matomo instance tied to the site.
What it is used for
The cookie's purpose is purely functional: it lets the site honor the visitor's choice without asking for consent again on every visit. If the visitor declined tracking, this cookie's presence tells Matomo not to collect statistics data about that person.
For the site owner, the cookie is useful as evidence that the consent mechanism is working correctly, and it helps avoid collecting analytics data without agreement, in line with legal requirements.
Does it require consent?
In CookieFix's classification, mtm_cookie_consent is categorized as strictly necessary, since its role is to remember a privacy preference rather than track the user for statistics or marketing purposes. Strictly necessary cookies do not require prior consent under Article 5 of the ePrivacy Directive (transposed in Romania via Law 506/2004), but they still must be listed in the site's cookie policy, with their purpose and duration.
- Site owners should list it correctly as "necessary", not as "statistics", in the cookie policy.
- Confirm this cookie does not itself trigger other tracking cookies before consent is given.
- If the Matomo installation is configured differently (without the built-in consent option), this cookie may not appear on the site at all.
How to block or delete mtm_cookie_consent
Visitors can delete or block this cookie from their browser settings (Chrome, Firefox, Edge, Safari), under per-site cookie management. Deleting it means Matomo will ask for the consent choice again on the next visit.
Because it is classified as strictly necessary, a CMP like CookieFix does not block it automatically before consent; it lets it function normally while blocking the actual statistics scripts (Matomo's main tracking) until the visitor agrees to the "statistics" category.
Frequently asked questions
No, it does not track visitor behavior. It only stores the consent choice made for the Matomo analytics service.
The long duration is intentionally set by Matomo so the consent choice stays remembered practically indefinitely, without repeatedly prompting the visitor.
No, it is classified as strictly necessary, so it can be set without prior consent, but it must still be listed in the cookie policy.
It is set by the Matomo instance the site uses (self-hosted or Matomo Cloud), configured by the site owner, not by an independent third party.