Firefox to Support Ad Blocker Extensions Amid Google’s Manifest V3 Shift

SEATTLE, Wash. — Mozilla announced that it will continue to support extensions built on Manifest V2, allowing popular tools like uBlock Origin to remain functional in its Firefox browser as Google Chrome transitions to the new Manifest V3 specifications.

As of mid-2025, Google plans to fully phase out support for Manifest V2 extensions, which includes significant changes to how extensions filter content. This change has drawn criticism from users and privacy advocates who argue it undermines ad and tracker blocking capabilities. The Electronic Frontier Foundation voiced concern that this transition would make it more difficult for users to manage their online experiences, particularly in blocking unwanted advertisements.

One significant alteration involves the replacement of the blockingWebRequest API, which allowed extensions high levels of customization in content filtering, with the more restrictive declarativeNetRequest API. This shift is expected to limit the effectiveness and flexibility of ad-blocking extensions on Chrome.

In contrast, Mozilla has reaffirmed its commitment to privacy and user control by retaining support for both blockingWebRequest and declarativeNetRequest APIs in Firefox. This move aims to provide developers with greater flexibility and to ensure that privacy-focused tools remain available to users. “Giving people choice and control on the internet has always been core to Mozilla,” a spokesperson said. “Our approach to Manifest V3 reflects that philosophy.”

Although many Firefox users have embraced extensions as a way to customize their browsing experience, Mozilla’s decision stands in stark contrast to Google’s timeline. Chrome users are already facing a decline in functionality for key extensions as developers adapt to the new limitations imposed by Google.

The disparity in approaches between browsers illustrates how user experiences can differ based on the underlying extension frameworks. While both Chrome and Firefox aim for compatibility, their implementations of the extensions API will lead to different outcomes for those looking to enhance their web browsing.

Mozilla has long advocated for user rights relating to data privacy and online transparency. As part of its ongoing commitment, Mozilla recently introduced new Terms of Use and Privacy Notice to clarify how it interacts with user data, ensuring users are informed on data collection practices. “We needed a license to allow us to make some of the basic functionality of Firefox possible. We’re building in a much different technology landscape today,” the spokesperson explained. “Being transparent about our operations is what we strive for.”

With the new terms implemented, Mozilla aims to address community concerns while reinforcing its policy to never sell user data. In emphasizing user control, Mozilla encourages Firefox users to review their data settings and customize their experience as they see fit.

For those looking to explore various ways to enhance their Firefox experience, Mozilla offers a collection of extensions designed to optimize browsing, empowering users to shape their online journey.