Mozilla Firefox will continue to support Manifest V2 alongside Manifest V3

Extensions are like apps for your browser, letting you customize and enhance your online experience. Nearly half of all Firefox users have installed at least one extension, from privacy tools to productivity boosters.

To build these extensions, developers rely on a platform called WebExtensions, which provides APIs — the tools that allow extensions to interact with web pages and browser features. Right now, all major browsers — including Firefox, Chrome and Safari — are implementing the latest version of this platform, Manifest V3. But different browsers are taking different approaches, and those differences affect which extensions you can use.

Firefox’s approach to Manifest V3 is shaped by our mission​

Principle 5 of the Mozilla Manifesto states: Individuals must have the ability to shape the internet and their own experiences on it. That philosophy drives our approach to Manifest V3.

• More creative possibilities for developers — We’ve introduced a broader range of APIs, including new AI functionality that allows extensions to run offline machine learning tasks directly in the browser.
• Support for both Manifest V2 and V3 — While some browsers are phasing out Manifest V2 entirely, Firefox is keeping it alongside Manifest V3. More tools for developers means more choice and innovation for users.

Giving people choice and control on the internet has always been core to Mozilla. It’s all about making sure users have the freedom to shape their own experiences online.

No limits on your extensions with Firefox​

Google began phasing out Manifest V2 last year and plans to end support for extensions built on it by mid-2025. That change has real consequences: Chrome users are already losing access to uBlock Origin, one of the most popular ad blockers, because it relies on a Manifest V2 feature called blockingWebRequest.

Google’s approach replaces blockingWebRequest with declarativeNetRequest, which limits how extensions can filter content. Since APIs define what extensions can and can’t do inside a browser, restricting certain APIs can limit what types of extensions are possible.

Firefox, however, will continue supporting both blockingWebRequest and declarativeNetRequest — giving developers more flexibility and keeping powerful privacy tools available to users. We’ll keep you updated on what’s next for extensions in Firefox. In the meantime, check out addons.mozilla.org to explore thousands of ways to customize your Firefox.