Download Firefox

Firefox is no longer supported on Windows 8.1 and below.

Please download Firefox ESR (Extended Support Release) to use Firefox.

Firefox is no longer supported on macOS 10.14 and below.

Please download Firefox ESR (Extended Support Release) to use Firefox.

Firefox Privacy Notice

Firefox Developer Edition
Release Notes

Release Notes tell you what’s new in Firefox. As always, we welcome your feedback. You can also file a bug in Bugzilla or see the system requirements of this release.

39.0a2
Firefox Developer Edition

April 3, 2015

Version 39.0a2, first offered to Firefox Developer Edition channel users on April 3, 2015

For more information about Developer Edition please see this MDN article and also this hacks.mozilla.org post.

New

Fixed

  • Improve performance of IPv6 fallback to IPv4

Changed

  • Removed support for insecure SSLv3 for network communications

  • Disable use of RC4 except for temporarily whitelisted hosts

  • NPAPI Plug-in performance improved via asynchronous initialization

Developer

Web Platform

Get the most recent version

All Firefox Developer Edition downloads