Google Chrome is moving to Manifest V3, but what does that mean for ad blockers?

Key findings

  • Extensions on old platforms will soon no longer work, Google's Manifest V3 represents a big change.
  • Vivaldi and Brave will continue to support Manifest V2 for some extensions until it is removed.
  • There are concerns about the impact of Manifest V3 on content blockers by replacing webRequest.



Google has been working on a new platform for Chrome extensions called Manifest V3 for some time now. A big focus is on ad blockers, but there are also many other extensions that will no longer work.

If you have extensions that are still based on Manifest V2, they will stop working very, very soon. Developers have long been told that this change is coming too. Google paused the upgrade process to listen to developer feedback and later resumed it in December last year. Since then, many apps have taken the leap and moved to Manifest V3.


While Manifest V3 certainly makes things harder for ad blockers, despite the headlines, they aren't going away. Things will get harder with Chrome 127 and above, but that's far from the end of ad blockers.

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What is Manifest V3? Which browsers will use it?

Extensions are based on manifest versions

Manifest V3 Transition

Manifest V3 is the latest extension platform for Chromium-based browsers and represents an overhaul of the architecture and guidelines that apply to browser extensions. It is a major update, although new Manifest versions are rare. Manifest V2 came out in 2012, and Manifest V1 extensions were also expected to be updated or become incompatible with later Google Chrome versions.


Manifest V3 has security, privacy, and performance implications. The biggest security improvement is the one that worries most people about the future of content blockers, which is the replacement of the webRequest API with the declarativeNetRequest API. There are also more restrictive permission models, explicit declarations of which websites the extension should have access to, and script injections are now more restricted.


Other browsers will also support Manifest V3 in the future, but most do not plan to drop support for Manifest V2. A prime example of this is Mozilla's Firefox, which reverse-engineered Chrome's extension API. Although Mozilla has stated that Firefox will support Manifest V3 in the future, there are no plans to drop support for Manifest V2. Most importantly, Mozilla will continue to specifically support the webRequest API for Manifest V3 extensions that still want to block content using that API.

As for Vivaldi, the developers behind it have already confirmed that they will continue to support Manifest V2 until it is eventually removed from Chrome. How that will work, however, is not entirely clear. Vivaldi installs its extensions through the Chrome Web Store, and Google will very soon start hiding Manifest V2 extensions there. Browsers like Brave are in the same situation as Vivaldi, although Brave has stated that they will explicitly work on supporting some Manifest V2 extensions, including uBlock Origin.


All Manifest V2 extensions will be completely removed from the Chrome Web Store in June 2025. Therefore, browsers that do not have their own central extension repository may have a bit of trouble installing these older, unsupported extensions.

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How does Manifest V3 break content blockers like uBlock Origin?

The changes to webRequest make it harder to block content

The process of loading a page when an extension uses the Web Request API


In 2019, when Google first announced Manifest V3, uBlock Origin developer Raymond Hill famously said that “this would be the death of uBO and uMatrix.” Furthermore, he went on to say that he found the change to be unnecessarily restrictive towards extensions, mentioning that “performance and privacy issues tend to be more with websites” than extensions.

To be clear, Google definitely had a problem with the webRequest API and the way it was used by extension developers. This API allowed an extension to all of your traffic and browsing behavior, giving it complete access to everything you do online. In 2019, Google reported that 42% of all extensions used this API in January 2018, and I can only imagine that number has increased since then.


Declarative Net Request API extension flow

Source: Google

Additionally, there are performance issues that come with using the webRequest API. Any extension that does this requires all network requests to go through that extension's processing first. If an extension is not optimized for performance, or if you have many extensions running on your PC using that API, you may experience slow loading pages. uBlock Origin has already disproved this point, but considering that 42% of extensions used the API back then, it's probably fair to say that not all of them were as optimized as, say, uBlock.


The difference with the declarativeNetRequest API is that the extension does not do all the filtering, but tells Chrome what to filter. Browser handles filtering instead. While the API was lackluster at first, Google continued to improve it and add more features based on developer feedback from AdGuard and Adblock Plus. When it was first introduced, it was unnecessarily restrictive and lacked many features to make it a suitable replacement, but that has improved over time and is now significantly better for developers.


While Google has some interest in preventing ad blocking, there are many reasons to believe that this has nothing to do with the company's position as an advertiser. There have certainly been many legitimate concerns about the plethora of extensions using the webRequests API, both from a performance and privacy perspective. While uBlock Origin and Adblock Plus arguably significantly improve performance, there is no doubt that many extensions have almost certainly made it worse.

Google also says about the declarativeNetRequest API:


This approach offers benefits for both user security and privacy, as well as performance. With a declarative approach, Chrome does not need to disclose sensitive data to the extension. The browser can perform the action requested by the extension without sending it all the data associated with the network request, because the extension has already specified the conditions under which various actions will be performed. This allows the extension to perform content blocking without needing access to all of a user's personal data.

While the company would like you to believe its stance is the right one, keep in mind that the company has faced several antitrust lawsuits over the years. Google is constantly under a lot of scrutiny, and the company needs to be fair with ad blockers to maintain some semblance of fairness. The company is already trying to find ways to prevent ad blockers from being used on services like YouTube, but directly attacking extensions that use the world's largest browser would almost certainly get the company in trouble.


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What happens to uBlock Origin?

There is already a replacement

uBlock Origin Lite filtering options

If you want to keep using uBlock Origin, there is already a new version called uBlock Origin Lite. It has the same filtering functionality as uBlock Origin, but hands the processing over to Chrome instead of the extension, and you can give it even more advanced filtering options by granting it more permissions. I use uBlock Origin and haven't noticed any real differences at all. It's just as good as regular uBlock, but offers additional benefits in terms of privacy and performance.


If you're looking for a list of the technical differences between uBlock Origin and uBlock Origin Lite, Hill has published a page on GitHub detailing the differences between them. There are some filtering features that aren't ready to be ported to Manifest V3 yet, and there are quite a few of them. These include:

Because the declarativeNetRequest API does not support the ability to enforce rules according to the top-level context, i.e. the URL in the address bar, the following features cannot be supported:

The declarativeNetRequest API does not allow filtering by the content of response headers and is therefore not possible:

The following filter options cannot be implemented in DNR rules:

CNAME discovery is the responsibility of each individual DNR implementation. At the time of this writing, no DNR implementation supports this feature.


There have also been allegations that uBlock Origin Lite is a malicious attempt to transition to Manifest V3, and that Hill is intentionally sabotaging the transition to try to fight back against Manifest V3. There is no evidence of this, and uBlock Origin Lite is a fully declarative implementation of uBlock, meaning it may fall behind in some ways, but it was designed with Manifest V3 in mind.

How can I determine which extensions no longer work?

Chrome has a built-in checker for you

Manifesto V3 "These extensions may no longer be supported"


If you want to see which of your extensions are disappearing, you can go to Settings top right and click on ExtensionsThis will take you to a page with all your extensions, including those that will no longer be supported by a future update of Chrome. These are the extensions that are not based on Manifest V3 and will stop working at a later date.

If you are looking for an alternative, click on the Find alternative The button will show you similar extensions based on Manifest V3. For most extensions, you can find replacements fairly easily. The extensions you were using were simply outdated and have been replaced anyway.

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