What is the dark_mode cookie?
The dark_mode cookie is set directly by the website being visited (a first-party cookie), not by an external provider. The name is generic and widely used: web developers commonly rely on it to implement a toggle between a page's light and dark visual themes.
It usually appears as soon as a visitor clicks the theme-switch button or toggle, or, in some implementations, on the very first page load if the site detects the user's operating system preference.
What data it stores
The cookie typically stores a simple boolean or short text value (for example "dark", "light", "true"/"false", or "1"/"0") indicating the visitor's active theme choice. The exact value format varies from site to site, since each developer implements it according to their own conventions.
The data stays stored locally in the visitor's browser and is sent only to the domain of the site that set it, not to third-party servers. It generally contains no personally identifiable information.
What it is used for
The cookie's purpose is strictly functional: it lets the site remember the visitor's visual preference across sessions, so they don't need to re-enable dark mode on every visit.
For the site owner, this cookie improves the user experience, particularly for visitors who prefer lower-contrast interfaces (for example in the evening or in low-light conditions), and has no role in statistics or marketing.
Does it require consent?
In CookieFix's classification, dark_mode falls under preferences (functional). Under current guidance from the Romanian data protection authority (ANSPDCP) and the ePrivacy Directive (transposed in Romania via Law 506/2004), read together with the GDPR, preference cookies that are not strictly necessary for the site's core functionality generally require the visitor's prior consent.
The site administrator should list this cookie in the cookie policy, with a clearly stated purpose and duration, and should only activate it after the visitor has given consent via the consent banner, unless it qualifies as strictly necessary in the site's specific context.
How to block or delete dark_mode
A visitor can delete or block this cookie at any time from the browser settings (Chrome, Firefox, Edge, Safari), in the site data/cookies section, either individually or by clearing all browsing data for that domain.
- Deleting the cookie resets the visual theme to the site's default value.
- Blocking cookies in the browser may prevent the theme preference from being remembered on future visits.
For site administrators, a CMP platform such as CookieFix can automatically block the script that sets dark_mode until the visitor gives consent, if it is classified as requiring prior consent.
Frequently asked questions
No, it's a simple functional cookie that doesn't store personally identifiable data and isn't used for tracking or advertising.
It's set directly by the visited website (first-party), implemented individually by each site's developers rather than a common external provider.
The typical duration is 1 year, though it can vary depending on each site's implementation.
The site will revert to its default theme (usually light mode), and the preference will need to be set again on the next visit.