What is the tuuid cookie?
tuuid ("tracking user ID") is an HTTP cookie set by Improve Digital, an ad-tech company operating a supply-side platform (SSP) that helps website publishers sell advertising inventory to advertisers through real-time bidding (RTB) auctions.
The cookie typically appears when a page loads an ad served through Improve Digital's infrastructure, or through a partner that integrates this SSP into the programmatic bidding chain. It may be set directly from an Improve Digital domain or from a sub-domain associated with its ad network.
What data it stores
tuuid stores a randomly generated unique identifier assigned to the visitor's browser the first time it is exposed to an ad served through the Improve Digital network. The exact value format may vary, but its role is that of a pseudonymous identifier, not directly identifying data such as a name or email.
The value is sent to Improve Digital's servers and, depending on the integration, to advertising partners involved in that specific bidding process, in order to link ad requests to the same visitor across multiple visits.
What it is used for
For Improve Digital, tuuid allows recognition of the same visitor across programmatic ad auctions, helps avoid double-counting users, and supports building behavioral statistics used for ad targeting.
For the website owner, this cookie is part of the technical chain that generates advertising revenue from the Improve Digital network or its partners, but it also creates an obligation to inform visitors and obtain consent before it is placed.
Does it require consent?
tuuid is classified as a marketing cookie (advertising/tracking). Under the ePrivacy Directive (as transposed locally, e.g. Romania's Law 506/2004) and the GDPR, this type of cookie requires prior consent from the visitor before being set, since it involves tracking for advertising purposes.
Website owners should: describe the cookie in their cookie policy, correctly classify it under the marketing/advertising category, and make sure the script that generates it does not run before consent is obtained. Data protection authorities can sanction the placement of marketing cookies without explicit consent.
How to block or delete tuuid
A visitor can delete or block tuuid through browser settings (Chrome, Firefox, Safari, Edge – cookies and site data section), or by using anti-tracking/ad-blocking browser extensions.
- Clearing site cookies resets the identifier, though it may be regenerated on the next visit.
- Private/incognito browsing modes prevent it from persisting across sessions.
For website owners, the correct approach is to technically block the script that sets tuuid until consent is given. A consent management platform like CookieFix can automatically block marketing scripts, including those tied to Improve Digital, until the visitor explicitly opts in.
Frequently asked questions
It does not contain sensitive data such as a name or email, but it is used for advertising tracking, which is why it is classified as a marketing cookie and requires consent.
Its typical duration is around 3 months, after which it expires automatically, though it can be regenerated on a new visit if the user consents to marketing cookies again.
Yes, any marketing cookie set through third-party ad integrations, including Improve Digital, must be disclosed in the cookie policy along with its purpose, category, and duration.
If your site runs programmatic advertising or works with ad partners that integrate Improve Digital as an SSP, tuuid may be set automatically when ads load; a site scan will confirm its presence.