Mozilla Enforces Transparency Rules for Data Collection in New Firefox Extensions

Mozilla has announced a major transparency push for its Firefox ecosystem, requiring all newly submitted extensions to declare their data collection and transmission practices within their code. From 3 November 2025, developers must specify these data handling details in the manifest.json file using the browser_specific_settings.gecko.data_collection_permissions key.

The change aims to ensure data policies are built into the extension itself and visible to users at install time and on the extension’s listing page, with a unified consent experience across permission prompts. Extensions supporting older Firefox versions, specifically prior to Firefox 140 on desktop or Firefox 142 on Android, will retain the obligation to provide users with clear data collection controls immediately after installation.

The deadline applies only to new extensions, while existing ones updating to newer versions are temporarily exempt, with Mozilla planning a broader rollout in the first half of 2026. Extensions must include the required declarations in all subsequent releases, and the submission system will automatically reject extensions that fail to disclose data practices.