Okay, so the previous demo doesn't actually track across eTLD+1's.

Here's another approach:

  1. Redirect to some tracking site. (It can be a different domain.)
  2. That tracking site does an AJAX request to fetch a tracking ID.
  3. The AJAX request responds with an ETag.
  4. The tracking site uses the referer header to bounce back to this page.
  5. When bouncing back, it transfers the tracking ID. In this demo, it's included as a query param.

EDIT: The referer header only gets passed if navigating within the same domain. But we can just manually pass it via URL param.

Here are some tracking sites. They are from different domains. You can pick one and see what tracking ID it returns.

The returned tracking ID should be consistent, even if you're calling the site from a different origin.


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