Google’s shift from Manifest V2 to Manifest V3 reshapes how browser extensions block network requests. The practical effect for users is that older ad blockers lose capability or stop working, while blockers built natively for Manifest V3 continue to block effectively under the new rules.
What is a browser extension manifest?
A manifest is a metadata file that tells the browser what an extension is, what version it is, what permissions it needs, and which browser versions it supports. Updates to the manifest format determine what features are available to extensions. When Google changes the manifest version, the set of APIs an extension is allowed to use changes with it.
Why is Google moving from Manifest V2 to Manifest V3?
Starting June 3, 2024, Google began the transition from Manifest V2 to Manifest V3 across Chromium-based browsers. Existing Manifest V2 extensions were gradually removed from the Chrome Web Store. Google’s stated goal is to improve the security, privacy, and performance of extensions by tightening how they intercept and modify network traffic.
The key technical change is the move from the blocking webRequest API to the declarativeNetRequest API. In Manifest V2, extensions could intercept any network request and modify or cancel it before it reached the network, a powerful and flexible model that ad blockers relied on. Manifest V3 replaces this with a rules-based model where the browser, not the extension, applies a predefined set of rules. This reduces the extension’s ability to read and alter arbitrary traffic, which Google argues is better for security, but it also caps how aggressively an extension can filter.
How does Manifest V3 change ad blocking?
The change has real consequences. Manifest V2 allowed dynamic, programmatic filtering that could adapt to new ad-delivery tricks quickly. Manifest V3 restricts the number of static rules (30,000) and dynamic rules (5,000) an extension can use, and it limits the kinds of request modifications possible. For users, this means some blockers lose features or flexibility, especially features like per-filter logging, fine-grained cookie control, and real-time dynamic rule generation at the scale the old API supported.
This is why several well-known blockers released scaled-down MV3 versions with missing or degraded functionality, and why a few, including uBlock Origin, saw their effectiveness reduced on Chromium browsers. Whether a blocker works well under MV3 now depends heavily on how skillfully its developers adapted to the declarativeNetRequest model within those rule limits.
How does ProBlocker handle Manifest V3?
ProBlocker was built native to Manifest V3 rather than ported from a Manifest V2 codebase. That means it uses the declarativeNetRequest API as its foundation and was designed within the rule limits from day one. The practical results:
- No reliance on deprecated blocking
webRequestcalls, so the extension remains compatible with current Chrome, Edge, Brave, Opera, and Vivaldi. - Continued ad and tracker blocking at the network level, including YouTube pre-roll, mid-roll, and overlay ads.
- Filter lists including EasyList, EasyPrivacy, uBlock Origin filters, and custom YouTube rules that are updated daily to keep pace with ad-delivery changes.
- Filtering runs locally on the device. ProBlocker collects zero user data, runs no analytics on your browsing, and has no account requirement.
For users, this means an ad blocker that stays within the new Chrome Web Store requirements without being reduced in functionality the way legacy ports are. It is a free extension with no paid tier and a Featured badge on the Chrome Web Store.
What happens if you keep a Manifest V2 blocker?
If you are running an older Manifest V2 ad blocker on a Chromium browser, several things are increasingly likely as the 2026 cutoff horizon passes: the extension may no longer update, may be removed from the store, or may stop working entirely when the browser drops Manifest V2 support. Functionality that depended on the old API, such as some dynamic filtering and logging, will not carry over.
The clean migration path is to switch to a blocker that is Manifest V3-native and actively maintained. For background on how blockers differ today, see our guide to what an ad blocker is, our best ad blocker comparison, and our explainer on YouTube ad blockers, which face the most frequent delivery changes.
What can users do right now?
If your current ad blocker still works and you are happy with it, there is no emergency. But if you notice degraded YouTube blocking, missing filter logs, or a stall in filter updates, consider migrating to a Manifest V3-native option. Here is a quick checklist:
- Open your browser’s extensions page.
- Note which features you actually use, whitelists, logging, custom filters.
- Choose a replacement that is built for Manifest V3, not merely ported.
- Import or recreate your whitelists before removing the old blocker.
- Remove the Manifest V2 blocker to avoid rule conflicts.
ProBlocker is one option that meets the “native to MV3, actively updated, free, and zero-data” criteria. It runs on Chrome, Firefox, Edge, Brave, Opera, and Vivaldi and is available in the Chrome Web Store.
Frequently asked questions
Will my Manifest V2 ad blocker stop working? It is likely to lose store support and eventually stop functioning as Chromium drops Manifest V2. Plan to migrate.
Does Manifest V3 make ad blocking impossible? No. It changes the mechanism and caps rule counts, but native MV3 blockers continue to block ads and trackers effectively.
Is ProBlocker free? Yes. ProBlocker is free with no paid tier, no subscription, and no account requirement.
Does ProBlocker collect my browsing data? No. Filtering runs locally and ProBlocker collects zero user data.
Which browsers support the Manifest V3 ProBlocker extension? Chrome, Firefox, Edge, Brave, Opera, and Vivaldi. The extension installs from each browser’s store or from the ProBlocker website.