Manifest V3 vs. Manifest V2: What Extension Developers Need to Know (Updated March 2024)

Are you an extension developer navigating the evolving landscape of browser extensions? This article provides the latest updates on Manifest V3 (MV3) and Manifest V2 (MV2), focusing on Firefox's plans and how they differ from Chrome. Stay informed and ensure your extensions thrive!

The Latest on Manifest V3 in Firefox

Firefox is actively collaborating with other browser vendors and community members through the W3C WebExtensions Community Group (WECG). The goal? To enhance extension APIs and improve cross-browser compatibility. This collaboration ensures that Firefox's implementation of MV3 is well-rounded and applicable across different browsers.

Continued Support for DOM-Based Background Scripts: Firefox maintains support for Event Pages and the blocking webRequest feature.
Chrome Compatibility: Extensions can be designed to work on both Chrome (121+) and Firefox (121+) by specifying both service worker-based background scripts (required by Chrome) and Event Pages. This offers flexibility for developers targeting multiple browsers.
Divergence from Chrome: Firefox's support for Event Pages and blocking webRequest enables functionalities not covered by Chrome's MV3, offering greater flexibility for certain use cases like advanced ad blocking.

Manifest V2: Firefox's Commitment to Developers

While Google Chrome is moving towards deprecating MV2, Firefox remains committed to supporting MV2 extensions for the foreseeable future. This provides stability and peace of mind for developers who have invested time and resources in MV2 extensions.

No Deprecation Plans: Firefox has no current plans to deprecate MV2.
Ample Notice: If a re-evaluation occurs in the future, developers will receive at least 12 months' notice to adjust their extensions.

Resources for Extension Developers

To stay updated on MV3 developments and migration strategies, utilize these valuable resources:

Migration Guide: Refer to the Manifest V3 Migration Guide for detailed information on adopting MV3.
FOSDEM Presentation: Watch the Firefox, Android, and Cross-browser WebExtensions in 2024 presentation for insights into the future of web extensions across different platforms.
WECG Meeting Updates: Keep an eye on the WECG meeting outcomes for the latest discussions and decisions.

Community Feedback and Support

Mozilla values developer feedback. Share your questions, concerns, and suggestions regarding Manifest V3 in the comments section, or reach out via email.

Manifest V3 vs. Manifest V2: What Extension Developers Need to Know (Updated March 2024)

The Latest on Manifest V3 in Firefox

Continued Support for DOM-Based Background Scripts: Firefox maintains support for Event Pages and the blocking webRequest feature.

Chrome Compatibility: Extensions can be designed to work on both Chrome (121+) and Firefox (121+) by specifying both service worker-based background scripts (required by Chrome) and Event Pages. This offers flexibility for developers targeting multiple browsers.

Divergence from Chrome: Firefox's support for Event Pages and blocking webRequest enables functionalities not covered by Chrome's MV3, offering greater flexibility for certain use cases like advanced ad blocking.

Manifest V2: Firefox's Commitment to Developers

No Deprecation Plans: Firefox has no current plans to deprecate MV2.

Ample Notice: If a re-evaluation occurs in the future, developers will receive at least 12 months' notice to adjust their extensions.

Resources for Extension Developers

To stay updated on MV3 developments and migration strategies, utilize these valuable resources:

Migration Guide: Refer to the Manifest V3 Migration Guide for detailed information on adopting MV3.

FOSDEM Presentation: Watch the Firefox, Android, and Cross-browser WebExtensions in 2024 presentation for insights into the future of web extensions across different platforms.

WECG Meeting Updates: Keep an eye on the WECG meeting outcomes for the latest discussions and decisions.

Community Feedback and Support

Mozilla values developer feedback. Share your questions, concerns, and suggestions regarding Manifest V3 in the comments section, or reach out via email.