Browser transition to Manifest V3 impacts uBlock Origin functionality

The transition from Manifest Version 2 (MV2) to Manifest Version 3 (MV3) is impacting the functionality of popular ad-blocking extensions, most notably uBlock Origin. Google Chrome and Microsoft Edge are phasing out support for MV2, which relies on the WebRequest API. This API allowed extensions to intercept and block network requests dynamically, a feature essential for comprehensive ad filtering.

In contrast, MV3 utilizes the declarativeNetRequest API. While Google argues this change improves security by preventing extensions from accessing sensitive user data, it limits the number of rules an extension can apply. For example, uBlock Origin previously utilized over 300,000 filtering rules, whereas MV3 imposes strict quotas that can reduce the precision of cosmetic filtering and the ability to track rapidly changing ad domains.

To maintain functionality, users can turn to alternative browsers. Mozilla Firefox, which uses the Quantum engine rather than Chromium, has confirmed that support for uBlock Origin is not changing. Brave, a Chromium-based browser, has also stated it will continue to support MV2 extensions and hosts uBlock Origin on its own servers. While a Lite version of uBlock Origin exists for MV3, it lacks the dynamic interception and cosmetic filtering capabilities of the original.