End User Interaction

Normandy has a few ways that end-users of Firefox can interact with it.



Users can view active and complete experiments they’ve participated in on about:studies. They can also manually end an active study using the Remove buttons on this page. This includes both preference experiments and add-on experiments (opt-out-studies).

The top of the page links to a SUMO article explaining studies, as well as to the opt-out preference.

Opt-Out Preference


Normandy adds a preference to about:preferences under the Privacy & Security tab, labeled “Allow Firefox to install and run studies” that defaults to being checked and links to about:studies. It controls the app.shield.optoutstudies.enabled preference in about:config.

If unchecked, the user will not be enrolled in any new studies.

The checkbox is linked to the one above it: “Allow Nightly to automatically send technical and interaction data to Mozilla”. If that preference is unchecked, the opt-out preference will also be unchecked and disabled until the user checks the data one again (at which point the opt-out preference becomes checked once more).

Ending a Study

The following events can cause a study to end before the add-on uninstalls itself:

  • The user uninstalls the add-on manually, or while Firefox is closed.

  • The recipe for the study is disabled; the study will end the next time the user fetches recipes.