Mozilla will soon require all Firefox extensions to disclose data collection practices

Mozilla has announced that starting November 3, 2025, all new Firefox extensions must specify in their manifest.json file whether they collect or transmit personal data. This is done via the browser_specific_settings.gecko.data_collection_permissions key. While this new requirement impacts only newly created extensions, new versions of already published extensions are not affected at launch. Extensions that do not collect or transmit any personal data must still declare this explicitly by using the none required value within the manifest property.

Following this update, details about an extension’s data collection practices will be shown to users during the installation process, along with its requested permissions. The same information will appear on the extension’s page on AMO, if publicly listed, and within the Permissions and Data section of the Firefox about:addons page.

If an extension supports Firefox versions earlier than 140 on desktop or 142 on Android, its developer must continue to offer users a clear way to manage data collection immediately after install. Once an extension version begins implementing the data_collection_permissions property, it must continue referencing this property in all future versions. Extensions required to use this property but failing to do so correctly will be rejected from the AMO signing process, with an explanatory message.