kobbe

Cross-domain tracking

Link visitor journeys across different root domains with explicit opt-in.

Cross-domain tracking is an advanced opt-in feature for sites that need to connect a journey across different root domains, such as a marketing site on example.com and an app on example-app.com.

By default, Kobbe does not link visitors across different root domains.

Kobbe stays privacy-friendly by default; this feature only runs when you use tracker.full.js and explicitly add data-allowed-hostnames.

Setup

Install the same Kobbe tracker token on each domain you want to measure as one site, then add the other allowed domains to the script tag:

<script
  defer
  data-token="YOUR_SITE_TOKEN"
  data-allowed-hostnames="app.example.com,shop.example.net"
  src="https://app.kobbe.io/tracker.full.js"
></script>

Use a comma-separated list of hostnames only. Do not include paths, query strings, email addresses, or user identifiers.

How it works

When a visitor clicks a link to an allowlisted hostname, the tracker appends a short handoff parameter to the destination URL. On the destination domain, the tracker reads the parameter, removes it from the address bar, and uses it for future events in that browser tab.

The raw handoff value is not stored in Kobbe. The collector hashes it server-side with the site ID, current UTC day, and a daily in-memory salt, then stores the resulting same-day anonymous visitor key.

Limits

  • Only explicit hostnames in data-allowed-hostnames are decorated.
  • The destination domain must also load the Kobbe tracker with cross-domain tracking enabled.
  • Cross-domain matching is designed for same-day journey and funnel analysis, not long-term user identification.
  • The tracker does not use cookies or localStorage for this feature. When cross-domain tracking is enabled, it uses sessionStorage to keep the handoff stable within the current browser tab.