Share identity across domains

When visitors move between domains that your organization owns, each domain maintains its own visitor identity by default. Without an explicit handoff, a visitor who clicks from one of your domains to another is treated as a new, unknown person on the destination site. This type of implementation fragments reporting and restarts personalization.

Cross-domain identity sharing solves this issue by appending an adobe_mc query-string parameter to the destination URL when a visitor clicks a link or is redirected. This parameter carries the visitor’s Experience Cloud ID (ECID), your organization ID, and a timestamp. When the destination page loads with a valid adobe_mc parameter, the Web SDK automatically reads it and applies the handed-off identity on its first Edge Network request, so both domains share the same visitor. The adobe_mc parameter expires after five minutes, so the destination page must load promptly after the redirect.

This use case covers identity sharing between websites on different domains. If you want to pass identity from a mobile app into a WebView or mobile web page, use mobile-to-web identity sharing instead.

Prerequisites

Before you begin, make sure that your implementation meets the following requirements:

Implement cross-domain sharing

You must configure identity sharing on every domain that acts as a source in a cross-domain handoff. If visitors can navigate in both directions between two domains, configure both domains as sources.

document.addEventListener("click", event => {
  // Check if the click was a link
  const anchor = event.target.closest("a");
  if (!anchor || !anchor.href) return;

  // Check if the link points to a domain you want to share identity with
  const url = new URL(anchor.href);
  if (!url.hostname.endsWith(".example.com") && !url.hostname.endsWith(".example.org")) return;

  // Append the identity to the URL, then navigate
  event.preventDefault();
  alloy("appendIdentityToUrl", { url: anchor.href }).then(result => {
    window.open(result.url, anchor.target || "_self");
  });
});

Receive identity on the destination domain

No additional code is required on the destination domain. When the Web SDK is present on the page and the URL contains a valid adobe_mc parameter, the SDK automatically extracts the ECID and applies it to the visitor’s identity map on its first Edge Network request.

Ensure that the destination domain meets the following conditions: