Desktop download as default

The stub installer is has been configured to serve a version of Firefox that will set itself as the default browser during installation if the stub attribution code includes the campaign value SET_DEFAULT_BROWSER.

Using stub attribution this way means it cannot be used for acquisition data, though it will still include the analytics session IDs if they are present.

At the moment (2025-07-14) if the switch download_as_default is enabled a checkbox should appear for users who match the following criteria:

  • their device supports stub attribution
  • their device supports Firefox
  • their device is running a version of Windows higher than 8.1

If they match the criteria a script will:

  • reveal the checkboxes
  • strip utm parameters from the URL
  • update the URL to only include the SET_DEFAULT_BROWSER campaign parameter
  • check the users's consent status to see if we should omitNonEssentialFields when initializing stubAttribution
  • initialize stub attribution to reflect the updated url

Unchecking the checkbox will not revert to the previous value of the stub attribution code.