Page referrer

CNIL recommendation

The removal of external referrer information;

Solution

The page_referrer field should be retained for internal links, but removed for external links. In practice, if the page_referrer domain corresponds to that of the website, this field is retained. Otherwise, it should be left blank.

We start by creating a variable containing our page_referrer.

Variables > New:

• Variable name: GA4 - Page Referrer Variable type: Event Data
• Key Path: page_referrer

Next, we create a second variable that will allow us to retrieve only the page_referrer domain. To do this, we'll use Simo Ahava's 'URL Parser' variable template.

Variables > New:

• Variable name: GA4 - Page Referrer Domain > - Variable type: URL Parser
• Variable type: URL Parser (via Community Template Gallery)
• URL Source: {{GA4 - Page Referrer}} (created previously)
• Component Type: Host Name
• Strip 'www': true

And the last variable to create is the page_referrer that we'll send to Google, which will be either empty or filled depending on the origin.

Variables > New:

• Variable name: GA4 - Page Referrer Pseudonymized
• Variable type: Lookup Table
• Input Variable: {GA4 - Page Referrer Domain}} (our previously created domain)
• Output Variable: (list of our authorized domains)
• input: example1.com / output: {{GA4 - Page Referrer}}
• input: example2.com / output: {{GA4 - Page Referrer}}
• Set default value: true (leave default empty)

We need to use this last variable in the configuration of the GA4 tag by adding a page_referrer field to the list of fields to be added/modified and assigning it this value.