Firefox Says it Will Continue to Support Manifest V2 Extensions

Mozilla has reaffirmed its commitment to supporting both Manifest V2 and Manifest V3 for browser extensions, ensuring continued access to powerful privacy-preserving tools like ad blockers.

This announcement comes as Google continues its phased deprecation of Manifest V2 in Chrome, which has already resulted in automatically disabling extensions that rely on the older framework, most notably, uBlock Origin, which counts 38 million users.

Although Google developed Manifest V3 (MV3), other browsers like Firefox and Safari have also adopted it with their own implementations. The primary reason for this adoption is to maintain compatibility with Chrome extensions, which dominate the market. However, Mozilla has made key modifications to MV3, including keeping the blockingWebRequest API, ensuring that developers and users retain access to advanced privacy and content-filtering tools.

Mozilla's statement, published earlier today, highlights its distinct approach to MV3. Unlike Chrome, which replaces blockingWebRequest with the more restrictive declarativeNetRequest API, Firefox will support both. This decision ensures that extension developers retain flexibility while allowing users to maintain their preferred browsing experience, including full-featured ad-blocking capabilities.

The company emphasized that user choice and control over internet experiences are core to Mozilla's mission, citing Principle 5 of the Mozilla Manifesto — the belief that individuals should have the ability to shape their online experiences.

Google abandons Manifest V2

Meanwhile, Google has begun the widespread deactivation of Manifest V2-based extensions, including uBlock Origin, in Chrome. Reports from last week confirmed that some users are seeing their extensions disabled with a message stating they are no longer supported. While the rollout is gradual, Chrome users globally are encountering automatic removals, with limited options beyond switching to a Manifest V3-compatible alternative like uBlock Origin Lite. However, many privacy-conscious users argue that the Lite version lacks the robust filtering options of its predecessor.

Mozilla's decision to support both Manifest V2 and V3 ensures that developers can continue to build powerful tools without restrictive API limitations. In contrast, Chrome users looking for similar functionality may need to explore third-party solutions or alternative browsers before Google completes the full phase-out of Manifest V2 by mid-2025.

As Google accelerates its transition to Manifest V3, Mozilla's decision to maintain Manifest V2 support positions Firefox as one of the last remaining browsers where users can fully control their online experience. The Tor Browser is based on Firefox, so the same applies to that project. Both are on our list of the 12 most secure browsers that protect users' privacy, so make sure to check them out.