Firefox 89 for developers

This article provides information about the changes in Firefox 89 that will affect developers. Firefox 89 was released on June 1, 2021.

Note

See also Looking fine with Firefox 89 on Mozilla Hacks.

Changes for web developers

Developer Tools

No changes.

HTML

No changes.

CSS

JavaScript

HTTP

No changes.

APIs

DOM

Removals

WebDriver conformance (Marionette)

Removals

  • The rotatable capability that is not part of the WebDriver specification is no longer used (bug 1697630).

Changes for add-on developers

Older versions