If you want to keep running full uBlock Origin on a major browser, there is now exactly one option. As PCWorld reported on August 13, Firefox is the last major browser that still supports the extension. Mozilla put it plainly on social media: “Our support for uBlock Origin isn’t going anywhere.”
Why MV2 Is Running Out of Road
uBlock Origin is built on Chrome’s Manifest V2 extension platform and depends on full permission to intercept and rewrite network requests. Chrome finished its MV3 migration in July 2025, moving to the declarativeNetRequest API — under MV3, the browser, not the extension, decides which requests get blocked, based on static rules. That stripped full-featured adblockers of the capabilities they need to detect and block ads, including the stubborn video ads that require dynamic filtering, leaving Chrome users with the reduced, MV3-compatible uBlock Origin Lite.
Chromium-based browsers have followed one after another. In practice, MV2 extensions lose the functions needed to properly detect and block ads on websites and in videos — the core of what a blocker like uBlock Origin does. Microsoft’s Edge team announced on its developer blog on August 7 that over the next few months, MV2 extensions will be “gradually turned off by default,” completing the transition for consumer browsers around the end of the year and for enterprises in 2027. Users will see notifications in the extension settings pointing to MV3 alternatives, and developers are being notified through Partner Center. Only 58 MV2 extensions remained in the Edge Add-On Store when the announcement landed.
Why Firefox Is the Last One Standing
Lay out today’s browser landscape and nearly all of it — Opera, Brave, Vivaldi, Samsung Internet — sits on Chromium, so it inherits the same platform decisions. The only two major non-Chromium browsers, Safari and DuckDuckGo, never supported uBlock Origin in the first place.
The remaining holdouts offer limited comfort. Opera says it will keep MV2 support “for as long as possible,” but already recommends users look for MV3-compatible alternatives. Brave keeps a short allowlist of MV2 extensions that currently includes uBlock Origin, uMatrix, NoScript, and AdGuard — but that is a list chosen by the browser vendor, not a platform commitment, and it can shrink. Everyone else is looking at the weaker uBlock Origin Lite or whatever built-in blocking their browser ships. To be fair, as PC Gamer notes, Chromium browsers are not banning adblocking outright — lightweight blockers still work. What is being squeezed out is the comprehensive, uBlock Origin mold of filtering.
Mozilla’s Differentiation Moment
Firefox runs on its own Gecko engine, immune to Chromium’s policy decisions, and Mozilla has committed to supporting both MV2 and MV3 going forward. It has leaned into the moment on social media; one post read: “Reminder that you can still just… use ad blockers on Firefox. Wild concept, we know.” For a browser whose market share has been squeezed for years, this is the clearest selling pitch it has had in a while: an independent engine is not just an engineering choice — it converts directly into a feature difference users can feel, exactly where ad and tracker fatigue is highest.
There is one gap: iOS. Full adblocking in Firefox for iOS has no announced timeline, though Mozilla says it is actively working on it. Apple’s rules mean every iOS browser is effectively a reskin of Safari’s WebKit, which limits how much of the desktop story can carry over.
What It Means for Users
There are three paths. To keep full blocking, switching to Firefox is the most direct move. Staying on Edge or other Chromium browsers means accepting Lite’s weaker filtering, or picking something like Brave with its MV2 allowlist. Enterprises have a grace period until 2027, which is enough time to plan, not enough to ignore. The bigger issue is structural: when what extensions are allowed to do is decided by one engine’s commercial interests, ad and tracker blocking — a capability that directly conflicts with those interests — becomes a privilege of whichever engines remain. Firefox is the last pillar, and that status alone is its best marketing.
Sources
- Firefox is now the last major browser that still supports uBlock Origin — PCWorld
- Firefox stunts on Edge as Microsoft gears up to neuter adblockers — PC Gamer
- Edge Browser: End date for Manifest V2 set — heise
AI-assisted summary compiled from the sources above, reviewed by a human before publishing.