What is the anj cookie?
anj is an HTTP cookie set on the .adnxs.com domain, belonging to AppNexus, a programmatic advertising platform later acquired by AT&T, rebranded as Xandr, and eventually folded into Microsoft Advertising. It is not set by the visited website directly, but by third-party servers called during ad delivery or real-time bidding (RTB) auctions.
It typically appears when a page loads an advertising tag, tracking pixel, or iframe from a partner within the Xandr ecosystem — for example within a display, video, or native advertising network.
What data it stores
The anj cookie generally stores a unique, anonymous identifier tied to the visitor's browser, used to link browsing activity to an advertising profile within the AppNexus/Xandr platform. The exact value format is not publicly documented in detail and may vary.
Data linked to this identifier (ad exposure history, interactions, bidding context) is sent to Xandr/Microsoft Advertising servers, not to the website operator.
What it is used for
The main purpose is targeted advertising: the identifier lets AppNexus/Xandr recognize the same visitor across multiple sites in the network, apply frequency capping, measure campaign performance, and participate in RTB auctions on behalf of advertisers.
For the site owner, the presence of this cookie usually indicates that at least one ad tag or monetization partner connected to the Xandr ecosystem is running on the page.
Does it require consent?
- CookieFix category: marketing (advertising/tracking).
- Under GDPR and the ePrivacy Directive (transposed in Romania via Law 506/2004), marketing cookies are not strictly necessary, so they require the visitor's prior, explicit consent before being set.
- The site administrator must: disclose the anj cookie in the cookie policy, classify it correctly under the marketing category, and ensure the script generating it does not run before consent is given.
How to block or delete anj
Visitors can delete or block this cookie from browser settings (Chrome, Firefox, Safari, Edge – the site data/cookie management section), or use ad-tracker blocking extensions. Browser-level blocking only stops that specific cookie, not any alternative fingerprinting methods advertising networks may use.
Site administrators must prevent Xandr/AppNexus tags from loading automatically before consent. A CMP like CookieFix can automatically block marketing scripts (including those setting the anj cookie) until the visitor explicitly accepts the marketing category in the banner.
Frequently asked questions
It does not contain sensitive data like names or emails, only an identifier used for advertising. It is still considered personal data under GDPR because it can be linked to an online behavioral profile.
Most likely an advertising partner, display network, or monetization platform you use runs auctions through Xandr, and the cookie is set indirectly through their tags.
Yes. As a marketing/tracking cookie, it requires the visitor's prior consent under GDPR and Romania's ePrivacy legislation.
Its typical duration is 3 months. Ad targeting based on this identifier can be limited by refusing marketing consent or through browser advertising privacy settings.