When you download and install Firefox from Mozilla’s website, we record and store information about how you initially reached our download page (such as the referring website or advertising campaign). This information helps us understand the effectiveness of our advertising campaigns and improve them.

Why do you need this information?

We want to understand which sites new users are coming from and whether they stick around to install Firefox. This information helps us understand the effectiveness of our advertising campaigns. See Mozilla's Firefox Privacy Notice for more information.

Do you keep my IP address or browsing history?

We do not save any IP addresses or other personally identifiable information in our collected telemetry data. When Firefox sends data to us, your IP address is temporarily collected as part of our server logs.

How do you collect this information?

This information is stored in the version of Firefox that you download and then made available to Mozilla through our telemetry system. We have also developed a unique download identifier for when you download Firefox, which allows us to capture if the download occurred, which in turn helps us understand how many installations come from third-party sites.

Where can I find more information about the Unique identifier?

You can find more information about the unique identifier here.

Can I remove the identifier before downloading?

The identifier gets generated when you click on the Download link. However, you can opt-out of telemetry collection and turn on the Do not Track feature after installing Firefox. Then, we will delete all information for your profile, including records containing the unique identifier.

Alternatively, you can choose to download Firefox from our archive site where no unique download identifier is generated at the time of download.

If I download Firefox from the archive site, will that opt me out of all telemetry collection?

Downloading Firefox from the archive site site will only remove the unique identifier. However, if you wish to opt out of all data and telemetry collection, make sure to opt out of opt-out of telemetry collection and turn on the Do not Track feature.