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How does Cross Domain Consent Sharing work?

Updated

Cross-Domain Consent Sharing (CDCS) lets the Usercentrics Consent Management Platform (CMP) share a visitor's consent choice when they move between participating websites and subdomains on the same root domain.

Please note

CDCS is available for CMP V2 and V3, and is included in the Business, Enterprise, and Advanced plans, as well as a Premium Add-on.

How does CDCS work?

As soon as CDCS is activated, our CMP injects an additional iFrame into the website and stores the consent information not only in the websites local storage but also in the iFrame's local storage. While the user switches to another (sub-)domain, the iFrames local storage is checked and if consent information is found, the consent information from the iFrame is stored into the local storage of the new (sub-)domain.

For example: mywebshop.com → checkout.mywebshop.com

This allows the CMP to apply the existing consent choice instead of displaying the consent banner again.

Requirements

For Cross-Domain Consent Sharing to work:

  • Use the same Settings-ID: All websites and subdomains that should share consent must use the same Settings-ID.

  • Enable CDCS: Enable Cross-Domain Consent Sharing in the Admin Interface under Configuration → CMP Settings. 

Browser restrictions

Cross-Domain Consent Sharing (CDCS) does not rely on third-party cookies. However, it uses a Usercentrics iframe and browser local storage to share consent information. Browser restrictions on third-party storage can therefore affect whether CDCS works as expected.

The following browser-related restrictions currently apply:

  • Safari: CDCS does not work with Safari because Safari does not share third-party local storage across different browser tabs. As a result, the feature cannot share the iframe's local storage across different tabs.
  • Firefox Browser: If the "Delete Cookies" option is enabled in Firefox, CDCS does not work because Firefox clears local storage when a new tab is opened, which prevents the consent information from being saved.
  • iOS browsers: Because Apple requires browsers on iOS to use WebKit, the same browser storage restrictions can affect CDCS on iOS devices.
  • Chrome: Starting with Chrome 115, CDCS does not work between different root domains, for example: a.com → b.com. This limitation is caused by browser restrictions on third-party storage and cannot be overcome by the standard CDCS implementation. As a result, the current CDCS implementation works between a root domain and its subdomains, for example:sub.a.com → a.com → another.a.com. For more information, see Storage Partitioning in Google's Privacy Sandbox documentation.

 

Improved consent sharing between subdomains

V2
V3

If visitors still see the CMP when switching between subdomains, you can use the improved consent sharing implementation for CMP V2.

Follow the steps in the Improved consent sharing between subdomains documentation.

This implementation isn't currently available for V3. Note that even where supported, this workaround doesn't bypass the third-party storage restrictions modern browsers now enforce (see Browser restrictions above), so its benefit is limited on both V2 and V3.

 

Privacy frameworks

CDCS can be used with CMP configurations supporting privacy frameworks such as GDPR, US privacy frameworks, and TCF.