Mozilla has announced a significant transparency initiative for its Firefox browser ecosystem, implementing mandatory data disclosure requirements for extension developers.
Starting November 3rd, 2025, all newly submitted Firefox extensions must explicitly declare their data collection and transmission practices within their code, marking a major step toward enhanced user privacy and informed consent.
New Manifest Requirements for Extension Developers
The compliance framework requires developers to specify data handling practices directly in the manifest.json file using the browser_specific_settings.gecko.data_collection_permissions key.
This technical implementation ensures that data policies are built into the extension itself rather than buried in external privacy documents.
Developers must indicate whether their extensions collect or transmit personal data, and those that do not engage in any data collection must explicitly declare this by setting the “none required” permission.
When users attempt to install a new extension, Firefox will automatically display this data collection information alongside the traditional permission requests.
This integration creates a unified consent experience where users can make informed decisions about both what the extension can access and how it handles their personal information.
The same disclosure will appear on the extension’s listing page at addons.mozilla.org and within the Firefox settings under the Permissions and Data section for installed extensions.
The November 3rd deadline applies exclusively to new extensions submitted to Mozilla’s add-on platform.
Existing extensions updating to newer versions are temporarily exempt from this requirement, though Mozilla has announced plans to extend the mandate to all extensions during the first half of 2026.
Developers will receive advance notice through the official add-ons blog before this broader rollout takes effect.
Once developers incorporate the data_collection_permissions declarations into any version of their extension, they must continue including these specifications in all subsequent releases.
Mozilla’s submission system will automatically reject extensions that fail to include required data disclosures, providing explanatory messages to developers about the rejection reasons.
For extensions supporting older Firefox versions specifically versions prior to Firefox 140 for desktop or Firefox 142 for Android developers retain the existing obligation to provide users with clear data collection controls immediately after installation.
Mozilla has indicated that additional features are being developed to facilitate this transition for both developers and users, with announcements forthcoming on the official blog.
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