How to Manage Firefox Experiments Using about:studies

This article provides a quick overview of the about:studies page in the Mozilla Firefox web browser, a built-in dashboard used to manage Shield and Normandy experiments. You will learn what these studies are, why Mozilla uses them, how to view the active and completed experiments running on your browser, and the exact steps to disable individual tests or completely opt out of future participation.

What are about:studies, Shield, and Normandy?

Mozilla regularly tests new features, performance improvements, and bug fixes on a small percentage of Firefox users before releasing them to the general public.

  • Shield: This is the framework Mozilla uses to run studies, gather telemetry data, and test new features in the wild. Shield allows Mozilla to measure how changes affect browser stability and user experience.
  • Normandy: This is the backend delivery system that pushes Shield studies, heartbeat surveys, and urgent configuration changes (like hotfixes) directly to your browser without requiring a full Firefox update.
  • about:studies: This is an internal page built into Firefox that provides transparency and control over the Shield and Normandy systems. It acts as a log showing every experiment your browser has participated in.

How to View Active and Past Experiments

You can check which experiments are currently running on your system at any time by accessing the studies dashboard.

  1. Open the Firefox web browser.
  2. Type about:studies into the address bar and press Enter.
  3. Review the page. You will see two distinct sections: Active studies (experiments currently modifying your browser) and Completed studies (expired tests that are no longer active).

Each entry includes a brief description of what the study does and its current status.

How to Opt Out of a Single Study

If a specific active experiment is causing issues or changes a feature in a way you dislike, you can disable it without turning off the entire system.

  1. Navigate to about:studies in your address bar.
  2. Under the Active studies section, locate the experiment you wish to stop.
  3. Click the Remove button located to the right of the study's description.

Firefox will immediately revert any changes made by that specific experiment, and the study will move to the Completed studies list.

How to Permanently Opt Out of All Studies

If you do not want Mozilla to enroll your browser in any future Shield or Normandy experiments, you can disable the feature entirely in your privacy settings.

  1. Open the about:studies page and click the Update preferences button at the top, or open the Firefox menu and select Settings.
  2. Click on Privacy & Security in the left-hand menu.
  3. Scroll down to the Firefox Data Collection and Use section.
  4. Uncheck the box next to Allow Firefox to install and run studies.

Note: Disabling studies will also prevent you from receiving urgent out-of-band hotfixes delivered via the Normandy system, meaning you will have to wait for standard browser updates to receive certain patches.

Advanced: Disabling Normandy via about:config

For advanced users who want to ensure the Normandy client is completely deactivated at the configuration level, you can modify the preferences directly.

  1. Type about:config into the Firefox address bar and press Enter.
  2. Click Accept the Risk and Continue.
  3. In the search bar at the top, type app.normandy.enabled.
  4. Double-click the app.normandy.enabled preference to change its value from true to false.