Controls in the settings menu allow you to turn off data collection from Firefox on your mobile devices. Here is what those control actually turns off:

• Firefox for Android, Firefox for iOS, and Firefox Focus collect data about installations and retention using a third-party tracking framework called adjust. This helps Mozilla determine the origin of the installation by answering the question, "Did this user on this device install the application in response to a specific advertising campaign performed by Mozilla?"

This framework consists of a open source software development kit (SDK) built into Firefox and a data-collecting Internet service backend run by the German company adjust GmbH.

• Firefox Focus also uses Mozilla’s telemetry system to measure basic interactions with the browser, such as the number of times you hit the erase button, select a search hint, or open a page in another browser. You can read more about this data collection here.

• Firefox Klar does not utilize Adjust. Mozilla’s telemetry system is turned off by default on Klar. You can turn telemetry on in the Klar Settings menu if you want to help us collect data to better understand and improve our product.

What data is collected and sent to the adjust backend?

For a new install, the application sends an anonymous "attribution" request to the adjust servers. This request describes how the application was downloaded, for example, whether it was downloaded directly via the App Store or through a marketing campaign link. The data includes an advertising ID, IP address, timestamp, country, language/locale, operating system and app version.

Firefox for Android, Firefox for iOS, and Firefox Focus will also occasionally send anonymous summaries about how often the application has been used. These summaries only include information regarding whether the app has been in active use recently and when.

Additionally, Firefox Focus will report what features of the application are being used. It will send an anonymous report containing the specific filters being selected and count how many times the search, browse and erase button is pressed. This is described in more technical detail in Install and event tracking with the Adjust SDK

Frequently asked questions

Why is data from Firefox Focus sent to a third-party?

Mozilla has high privacy standards and expects the same of vendors that provide us with services. We use a mobile analytics solution called Adjust. We selected Adjust because they are the best analytics solution for Firefox Focus and because they maintain strong protections for users. Adust also holds ePrivacy certification and complies with strict German privacy laws. Equally important, Adjust’s SDK is open source. This provides greater transparency for anyone that wants to understand exactly what data Adjust collects. The information that we send to Adjust is described here.

Does Firefox Focus track what sites users have visited?

Users’ browsing history on Firefox Focus never leaves the devices and is not sent to Mozilla or our mobile analytics vendor Adjust. Like most web browsers, Focus keeps a local copy of your browsing history on the device during a browsing session. This is true for nearly all browsers and enables functions such as changing colors of links that have already been clicked. Focus makes it easy to remove your browsing history from your device with a single tap on the Erase button located in the top right corner of each Focus browser window.

Does Mozilla collect personally identifiable information from Firefox Focus?

Neither Mozilla, nor our mobile analytics vendor Adjust, receive personal information from Focus users. For example, we do not receive usernames, email addresses, or URLS from Focus users.

What is the advertising ID and what is is used for?

The Adjust SDK integrated into Firefox Focus utilizes Apple’s IDFA - “ID for Advertisers.” This is an identifier that Apple makes available to advertisers for iOS devices. Apple assigns and manages the IDFA for each device, and allows iOS users to turn-off their IDFA or periodically reset it (resetting the IDFA reduces the ability of advertisers to track users).

Our mobile analytics vendor Adjust uses this IDFA to attribute a Focus app installation to a previously served advertisement for Focus. In other words, Adjust determines if iOS users discovered Focus by clicking on a mobile advertisement to install the Focus app, and then can provide aggregate numbers of app installations to Mozilla. We think Focus is a great privacy product and we want people to know about it. Adjust helps us know that our message about Focus is effective.

Mozilla does not have access to this IDFA, nor do we receive information about the IDFA in the aggregated activity summary reports we receive from Adjust. If the user enables “Limit Ad Tracking” in the the iOS Privacy Settings, then the IDFA is also not used in any communication with Adjust.

Why does Firefox Focus enable data collection by default?

The Firefox Focus browser is a new Firefox product. With all new products we seek to establish market fit validation as quickly as possible. We decided to take an opt-out approach to gain insight from a more diverse group of users about their first interactions with the product. We believe such approach helps us gather usage information that is as unbiased as possible in order to really understand how Focus is being used and consequently how it can be improved.