uBlock Origin and ad blockers: what works, what to remove

A good content blocker removes adverts, trackers and links to known malicious sites, which makes it one of the most useful security tools a browser can have. The best known, uBlock Origin, now works in full only in Firefox and a few other browsers, after Google removed it from the Chrome Web Store on 31 August 2026. At the same time, every extension you install can see the pages you visit, so the rule is one trusted blocker and as few other extensions as you can manage.

This is the last of three short articles on browser privacy and security, after what Incognito mode does and choosing a privacy browser.

In short

• Chrome moved to Manifest V3 and removed the full uBlock Origin from its store on 31 August 2026. The lighter uBlock Origin Lite replaces it, with fewer features.
• The full uBlock Origin still works in Firefox and LibreWolf, and Brave has its own blocker built in.
• Any extension that can "access your data for all websites" can read every page you visit and what you type into it.
• Keep one trusted content blocker and as few other extensions as you can. Audit the rest every few months.

What changed in Chrome?

Chrome now follows Manifest V3. Browser extensions follow a set of rules from the browser maker called a manifest. Chrome has moved from version 2 of these rules to version 3 (Manifest V3), which limits how an extension can inspect and block web requests. Google's timeline shows Manifest V2 extensions stopped working in Chrome during 2025 and were removed from the Chrome Web Store on 31 August 2026.

uBlock Origin has no Manifest V3 version. The free and open-source blocker needs the capabilities Manifest V2 provided, and its developer has not made a Manifest V3 version. Instead there is uBlock Origin Lite, a lighter blocker built for the new rules. Its own documentation says it is not a like-for-like replacement: it handles fewer advanced filters, copes less well with sites that fight ad blockers, and updates its filter lists only when the extension itself updates.

Where does the full uBlock Origin still work?

Firefox keeps supporting what it needs. Mozilla has said Firefox will keep supporting the extension features uBlock Origin needs, alongside Manifest V3, and has promised at least twelve months' notice if that ever changes. uBlock Origin's own wiki says it works best on Firefox, where it can do things no other browser allows, such as uncloaking trackers that hide behind a site's own domain name.

Your options, as at October 2026:

uBlock Origin and uBlock Origin Lite are both licensed under the GNU General Public Licence version 3. By default, uBlock Origin's lists block known malware sites as well as adverts and trackers.

Why are browser extensions a risk?

Some permissions are very broad. An extension that asks to "access your data for all websites" can, in Mozilla's words, read any page you visit and what you type into it, including usernames and passwords. Password managers and ad blockers need that access to work. A calculator or a coupon finder does not.

The risk does not stop at installation:

• Extensions update themselves. Google warns that if an extension developer's account is taken over, an attacker can push malicious code straight to every user. That is how at least one well-known extension was turned into a tool for stealing signed-in sessions, as our article Infostealer malware: how to protect your business passwords describes.
• Store review is a filter, not a guarantee. Google reviews extensions and removes and remotely disables those it finds dangerous. Mozilla's Recommended extensions get a staff security review and ongoing monitoring, and developers cannot pay for the badge. Neither store promises that everything else is safe.
• More extensions make you easier to recognise. The Electronic Frontier Foundation notes that unusual add-ons can make a browser's fingerprint more distinctive.

How do you audit your browser extensions in ten minutes?

1. List them. Open the extensions page of your browser and list everything installed.
2. Remove the unknown and the unused. Remove anything you do not recognise or have not used in a month.
3. Compare access with purpose. For each one left, compare what it can access with what it does. A tool that only needs one site should not have access to all of them.
4. Limit site access. Where the browser allows it, limit site access to "on click" or to specific sites.
5. Keep one blocker. Two blockers do not block twice as much, and each one adds risk.
6. Run Safety Check in Chrome. It flags extensions that contain malware or have been withdrawn from the store.
7. Repeat. Audit every few months, and whenever an extension suddenly asks for new permissions.

What should your extension list look like?

• One trusted content blocker: uBlock Origin on Firefox, Brave Shields in Brave, or uBlock Origin Lite on Chrome and Safari.
• A password manager extension if you use one, from its official developer.
• Nothing else unless you use it every week and can say why it needs the access it has.

Read next:

• Choosing a privacy browser: Firefox, Brave, LibreWolf and Safari, part 2 of this series.
• Infostealer malware: how to protect your business passwords, on how stolen sessions are used.
• Passkeys and hardware security keys explained, on sign-ins a stolen password cannot reuse.

Blocking happens in the browser. If you would like someone to look at the browser and extensions on a computer with you, Noiz remote support works by ticket and can connect to your computer with your agreement.

Sources

• Chrome for Developers, Manifest V2 support timeline: https://developer.chrome.com/docs/extensions/develop/migrate/mv2-deprecation-timeline
• uBlock Origin, README and licence: https://github.com/gorhill/uBlock
• uBlock Origin wiki, about Chrome's "This extension may soon no longer be supported": https://github.com/gorhill/uBlock/wiki/About-Google-Chrome's-%22This-extension-may-soon-no-longer-be-supported%22
• uBlock Origin wiki, works best on Firefox: https://github.com/gorhill/uBlock/wiki/uBlock-Origin-works-best-on-Firefox
• uBlock Origin Lite, FAQ: https://github.com/uBlockOrigin/uBOL-home/wiki/Frequently-asked-questions-(FAQ)
• Mozilla, Manifest V3 and Manifest V2 (13 March 2024): https://blog.mozilla.org/addons/2024/03/13/manifest-v3-manifest-v2-march-2024-update/
• Mozilla, Firefox and ad blockers (25 February 2025): https://blog.mozilla.org/en/firefox/firefox-manifest-v3-adblockers/
• Mozilla Support, permission request messages for Firefox extensions: https://support.mozilla.org/en-US/kb/permission-request-messages-firefox-extensions
• Mozilla Support, Recommended Extensions program: https://support.mozilla.org/en-US/kb/recommended-extensions-program
• Google Online Security Blog, staying safe with Chrome extensions (20 June 2024): https://security.googleblog.com/2024/06/staying-safe-with-chrome-extensions.html
• Chrome for Developers, stay secure: https://developer.chrome.com/docs/extensions/develop/security-privacy/stay-secure
• Chrome Web Store Help, install and manage extensions: https://support.google.com/chrome_webstore/answer/2664769
• Brave Shields: https://brave.com/shields/
• EFF, Cover Your Tracks: https://coveryourtracks.eff.org/learn

Note: while some of this content was produced with the help of AI, the final editing has been done by a real human being.