What is the CMPS cookie?
CMPS is an HTTP cookie placed by the .casalemedia.com domain, owned by Casale Media, the company that operates the Index Exchange programmatic advertising exchange. It typically appears on a website when a page loads an ad tag, a header bidding module, or a pixel from a publisher partner connected to the Index Exchange ecosystem.
Since it is set on the vendor's domain rather than the visited site's domain, it is a third-party cookie, common in ad-tech infrastructure running in the background on many sites that use programmatic advertising.
What data it stores
CMPS generally stores an identifier that Casale Media uses to recognize a browser or user across visits and to associate that identifier with advertising segmentation data. The exact value format is not publicly documented and may vary; no reliable technical details about its internal structure are known.
Data collected through this cookie is sent to Casale Media / Index Exchange servers and may be shared within the programmatic bidding chain (RTB) with other advertising partners involved in serving the ad.
What it is used for
The main purpose of the CMPS cookie is to support programmatic advertising processes: identifying the browser during real-time bidding auctions, measuring campaign performance, and building audience segments for ad targeting.
For a website running ads through partners connected to Index Exchange, this cookie helps monetize ad space by enabling relevant ad delivery and performance reporting back to advertisers and agencies.
Does it require consent?
CMPS is classified as a marketing cookie (advertising/tracking). Under the GDPR and the ePrivacy Directive (transposed in Romania via Law 506/2004), this type of cookie requires the user's prior, explicit consent before it is placed or read.
- Site owners must list it in their cookie policy under the marketing category.
- The cookie must not be set automatically on page load if the visitor has not accepted the marketing category.
- Refusing consent must not block access to the site's core content.
How to block or delete CMPS
A visitor can delete or block this cookie from browser settings (Chrome, Firefox, Edge, Safari — per-site cookie management) or use ad-tracking blocking extensions.
For site owners, the recommended approach is using a Consent Management Platform such as CookieFix, which automatically blocks scripts and ad tags connected to Index Exchange/Casale Media until the visitor gives consent for the marketing category, preventing the cookie from being set without authorization.
Frequently asked questions
It is not malicious; it is a standard ad-tech tool used for ad auctions and targeting. It is still classified as a tracking cookie and must be handled according to consent rules.
It is set by Casale Media, the company behind the Index Exchange programmatic advertising platform, typically when an ad tag or header bidding module loads on the page.
The typical observed duration is around 3 months, after which it expires automatically unless renewed on a new visit.
Yes, as a marketing cookie it requires the user's prior consent under the GDPR and Law 506/2004 before being set in the browser.