Firefox is to get a new extension API from Chrome

Chrome is already using Manifest v3, Firefox is set to follow this year. However, ad blockers are not restricted. In its addons blog, the development team of Mozilla’s Firefox browser describes in detail its plans for the implementation of the so-called Manifest v3. According to the announcement, the team intends to accept extensions that use the new Manifest v3 set of rules from the next year 2022. The technical requirements for this are to be implemented in Firefox by the end of the current year 2021.

Manifest v3 is a set of rules and, among other things, a collection of interfaces that are available for use for extensions in the browser. The introduction of Manifest v3 in the Chrome browser led to numerous discussions and far-reaching criticism of the manufacturer Google, as the team is actively restricting the functionality of existing technologies, especially ad blockers. The Chrome browser has been using Manifest v3 since the end of last year.

However, the Firefox makers at Mozilla have stated earlier that they are keen to keep their own interfaces for extensions as compatible as possible with those of Chrome. There is no obligation for this, however, and the APIs already differ in some specific places.

Firefox keeps Webrequest API

This referred explicitly to the Webrequest API or its replacement Declarative Net Request (DNR) used by Google, which causes the restrictions on the ad blockers. Mozilla writes: 

“This affects the capabilities of extensions that process network requests (…) by limiting the number of rules an extension can use and the filters and actions available.”

According to the announcement, Firefox will support both DNR and the Web request API in the future. This should enable developers to use a uniform code base for both browsers. With both APIs, developers can still choose which of the interfaces is best for their purpose, explains Mozilla. The Web request API should be supported until there is a better replacement than DNR.

In addition to the discussions about the Web request API, the move to Manifest v3 brings many other changes. Mozilla is working on strict page isolation, service workers for background services, strict control of which extension is allowed to run where, or a restriction on the execution of dynamic code.