Cross-domain tracking

The BEX booking flow usually spans more than one domain, for example from your site to the checkout portal. To track a visitor as one user across these domains, set up both GA4 cross-domain measurement and Google Ads cross-domain linking.

Domains in the booking flow

Part of the flow

Example domain

Add to cross-domain list

Add as unwanted referral

Your site

www.bexdemo.nl

Yes

No

Checkout portal

www.bexdemo.nl/checkout

Yes

No

Payment provider

mollie.com

No

Yes

GA4 cross-domain measurement

Use one GA4 property with one web data stream, and the same tag ID on all domains.
For more details, see Google’s own support on GA4 cross-domain measurement.

  1. In GA4, go to Admin → Data streams and select your web stream.

  2. Go to Configure tag settings → Configure your domains.

  3. Add your site and checkout portal domains, for example sunnydunes.com and checkout.bex-example.com.

  4. Click through the flow and check that the _gl parameter is added to the URL when you move to another domain.

Keep the _gl parameter
If a redirect removes query parameters from the URL, cross-domain tracking breaks. Make sure every redirect in the flow keeps _gl.

Unwanted referrals

When a visitor returns from the payment provider, GA4 can treat the payment provider as a new traffic source. The purchase is then attributed to the payment provider instead of the original channel, such as Google Ads.

  1. In GA4, go to Admin → Data streams and select your web stream.

  2. Go to Configure tag settings → Show more → List unwanted referrals.

  3. Add the payment provider domain, for example pay.payment-example.com.

Don't add payment domains to the cross-domain list.
You don't control the payment provider's pages, so the GA4 tag can't run there. List them as unwanted referrals instead.

Google Ads cross-domain linking

  1. Add a Conversion Linker tag that fires on all pages.

  2. Enable Enable linking across domains and add your site and checkout portal domains under Auto Link Domains, for example sunnydunes.com, checkout.bex-example.com.

  3. (Optional) Enable Decorate Forms if forms submit to another domain.