What is the guest_id_ads cookie?
guest_id_ads is an HTTP cookie set by X (formerly Twitter) when a visitor lands on a page that loads X platform resources: a „Follow” or „Tweet” widget, an embedded X timeline, or, most commonly, the X Ads (formerly Twitter Ads) conversion pixel used for remarketing and campaign measurement.
The cookie is set even if the visitor has no X account, since the platform assigns a „guest” visitor identifier to recognize them later for advertising purposes.
What data it stores
The cookie stores a unique identifier generated by X, used to distinguish the visitor's browser for advertising and conversion-attribution purposes. It does not contain login credentials and does not directly identify the person, but it is treated as an online identifier under GDPR since it can be linked to other data X collects.
The value is sent to X's servers (twitter.com / x.com and their associated advertising domains) each time X resources load on the site.
What it is used for
For X, the cookie helps build advertising profiles, measure the effectiveness of X Ads campaigns (how many site visitors came from an X ad), and support remarketing — showing ads to site visitors when they later return to X.
For the site owner, this cookie's presence usually comes from embedding an X Ads conversion pixel or a social widget, not from a core site function.
Does it require consent?
guest_id_ads falls under the marketing/advertising category. Since it is used for tracking and remarketing purposes, it requires the user's prior consent under ePrivacy Directive 2002/58/EC (implemented in Romania via Law 506/2004) and GDPR's lawful-processing principles.
Site owners must list it explicitly in their cookie policy under the marketing category and must not allow the X script (widget or pixel) to load before the visitor grants consent through a consent banner.
How to block or delete guest_id_ads
A visitor can delete or block this cookie from their browser settings (Chrome, Firefox, Edge, Safari — per-site cookie controls), or use the cross-site tracking protections built into most modern browsers.
- Manually deleting cookies for the twitter.com/x.com domain
- Enabling browser anti-tracking protection
- Using dedicated tracker-blocking extensions
For site owners, the correct approach is to load the X script (social widget or conversion pixel) only after consent is given. A CMP such as CookieFix can automatically block these scripts until the visitor accepts the marketing category, preventing the cookie from being set prematurely.
Frequently asked questions
It's a marketing cookie set by X (Twitter) to assign a guest visitor identifier, used for advertising and remarketing purposes, even if the person has no X account.
Yes. As a marketing/tracking cookie, it requires the visitor's prior consent under ePrivacy and GDPR and cannot be set automatically.
It typically lasts 2 years, though the exact duration may vary depending on X's policies.
It usually comes from an embedded X social button (Tweet/Follow), a widget, or the X Ads conversion pixel used for advertising campaigns.