Cross-Domain Conversion Tracking With First-Party Events

Cross-domain tracking keeps a marketing journey intact when the landing page and conversion run on different domains. Add both domains to one Hardal signal, carry an approved journey identifier into the second domain, and send the confirmed conversion from its first-party source.

Common architecture

www.example.com -> checkout.example-payments.com -> backend confirmation
        |                       |                         |
        +-----------------------+-------------------------+
                         one Hardal signal

The same pattern applies to a content site and app domain, an airline site and booking engine, or several storefronts that share a checkout.

Implementation steps

1. Create or select a signal in the Hardal dashboard.
2. Add the Hardal snippet to each web domain that should send events.
3. Allowlist the domains in the signal configuration.
4. Pass a short-lived journey token into the conversion flow where your policy permits it.
5. Send the final purchase, application, or booking event from the source that confirms it.
6. Test allowed origins, consent behavior, deduplication, and referral exclusions.

Do not put email addresses, account IDs, booking references, or other personal data in query parameters. Use an opaque token and resolve it inside your first-party system.

Cross-domain tracking

Validate the handoff

• Confirm the landing event includes campaign context.
• Confirm the second domain receives the approved journey token.
• Confirm the backend conversion uses a stable event ID.
• Compare source conversions with events received by Hardal.
• Check that payment and authentication domains do not become false referrals.