It's helpful for Mozilla engineers to be able to measure how Firefox behaves in the real world. As you use Firefox, the Telemetry feature sends technical and interaction data to Mozilla on a daily basis. To learn more about what data Mozilla receives and how it's used, see Mozilla's Firefox Privacy Notice.

How do I opt-in or opt-out of sending performance data?

Firefox collects technical and usage data by default but you can turn this off at any time.

1. In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button and select Settings.
2. Select the Privacy & Security panel.
3. Scroll down to the Firefox Data Collection and Use section.
4. Check or uncheck the box next to Allow Firefox to send technical and interaction data to Mozilla.

Telemetry Data

To view the information about performance, hardware, usage and customization data collected by Telemetry, enter about:telemetry in the address bar. A Telemetry Data report will open.

To learn more about telemetry and Firefox data collection, see the Telemetry collection and deletion article.