firefox Manifest V3
Recently Mozilla developers who are in charge of Firefox, gave to know your plans regarding support for Chrome manifest versions 2 and 3 in Firefox. And, although Google intends to stop supporting plugins that use the second version of the manifest in the test versions of Chrome 127, Mozilla has decided not to stop supporting the second version of the manifest in the foreseeable future.
In addition to it Mozilla assures that it will maintain the ability to launch add-ons that use functions not available in the third version of the manifest. The decision not to make Firefox fully compatible with version 3 of the Chrome manifest remains in place. Firefox will retain the full webRequest API, which will be changed to read-only mode in Chrome.
Furthermore, Firefox will use the event pages mechanism to retain support for running DOM-based background scripts. While the third version of the manifest requires the use of Service Workers, Service Workers-based background scripts are not yet supported in Firefox. However, developers will have the opportunity to define both an event page-based handler and Service Workers-based scripts in the plugin, allowing them to create plugins that comply with the third version of the manifest and work in Chrome and Firefox.
The Chrome manifest defines the capabilities and resources available to extensions written using the WebExtensions API. Since version 57, Firefox completely switched to using the WebExtensions API to develop plugins, abandoning XUL technology.
This transition allowed to unify the development of plugins with other platforms such as Chrome, Opera, Safari and Edge, simplified the transfer of plugins between different web browsers and fully enabled multithreaded mode of operation. Firefox provides near-full compatibility with the second version of the Chrome manifest to unify plugin development with other browsers.
As part of an initiative to make it easier to create high-performance, secure plugins, and make it harder to create slow and insecure plugins, Google has developed version three of the manifesto. However, There has been discontent mainly due to the read-only translation of the webRequest API in the third version of the manifesto.
The main concern with the third version of the manifest lies in the translation of the webRequest API to read-only mode, which has generated some discontent among developers. This API allowed you to connect your own controllers that had full access to network requests and could modify traffic dynamically. Instead of the webRequest API, the third version of the manifest added the declarativeNetRequest API, which has more limited capabilities and provides access to the built-in filtering engine without allowing the use of its own filtering algorithms.
Despite these differences and challenges, Firefox has implemented important features by adopting the third version of the Chrome manifest:
- A new declarative content filtering API that retains support for the old blocking mode of the webRequest API.
- Implementation of the Event Pages mechanism: This mechanism removes the limitations associated with the use of Service Workers and allows background page additions to comply with the requirements of the third version of the manifest.
- Firefox has introduced a new permissions model that requires user approval for each site the add-on wants to work on.
- A “Unified Extensions” button has been added to directly control each plugin's access to sites.
- Change to cross-origin request processing: The same permission restrictions apply to content processing scripts as they do to the main page they are embedded in.
- Firefox has implemented restrictions to prevent the execution of code downloaded from external sources, thus increasing the security of add-ons.
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