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Firefox 33 Find out what is new

All versions of the Firefox web browser will be updated to the next major version in the coming 24 hour period. This means that the stable version of the browser, currently at version 32.0.3, will be updated to version 33.

In addition, Firefox Beta, Aurora and Nightly versions will be updated to version 34, 35 and 36 respectively.

It is interesting to note that this Firefox ESR 24.x reaches end of support and that Firefox ESR 31.x will take over from this point onwards.

It is expected that Mozilla will publish all updates on October 14, 2014. The update announcement will be published on the same date and users with automatic updates enabled will receive the new version automatically.

Tip: You can find out which version of the browser you are running by loading about:support in the address bar. There you find the current version listed under Application Basics.

mozilla firefox 33

Firefox 33 Download

It is recommended to download Firefox 33 directly from Mozilla, either by using the browser's update feature or by downloading it directly from the Mozilla website or FTP server.

Many third-party download sites host Firefox 33 before releases and while it may be tempting to download it from those sources, it is possible that this is not the final version of the web browser after all.

There have been incidents in the past where last minute changes resulted in a different build being picked as the official release build.

We have published a download guide for Firefox that explains everything there is to know about that process. Check it out if you are stuck or want direct download links.

Firefox 33 Changes

Firefox 33 introduces several changes to the browser. Some of the changes are visible on the frontend while others improve the browser in the backend.

Windows Off Main Thread Compositing (OMTC)


This new feature provides a smoother browsing experience while consuming less resources. It would get too technical to get into details only this much: Mozilla moved compositing to a second thread to make the main thread loop more responsive.

You find all details on Benoit Girard's blog post about the new feature.

OpenH264 Support

openh264 support

When you open Firefox 33 for the first time after upgrading the browser or installing it anew, you will notice that the OpenH264 plugin is now included under plugins automatically.

This can be used by the browser to decode and encode H.264 video so that these videos play in the browser now. If you check the HTML5 page on YouTube for instance you will notice that Firefox supports H.264 now which it did not before.

Search Suggestions on about:home and about:newtab

search suggestions

Firefox displays a Google search form on the new tab page and the home page by default (click here for instructions to remove it).

The search has been improved so that it displays suggestions now when you use it on the page.

Location bar search improvements

firefox local queries

Mozilla has improved how single-word queries and local query searches are handled in the browser. If you search for a number such as 8676586 for instance, you were previously taken to the .com domain regardless of whether it existed or not.

While you could prevent that by adding a ? in front of the query, this is no longer necessary in Firefox 33 as the browser will search automatically by default and without delay.

A prompt is displayed however that you can use to go to the domain instead if that is where you wanted to go in first place. The result is that single-word queries are displayed much faster now by the browser.

Session restore reliability improvements

Mozilla improved the backup process of Firefox sessions in Firefox 33. The new process introduces new files and locations for session restore data.

In the end, it should make the feature more robust so that it is less likely that session restore won't work (for instance because of corruption or after an upgrade).

You can read about the new session restore in Firefox 33 here.

Enhanced Tiles did not land in Firefox 33. The feature that populates the new tab page with tiles will land in Firefox 34 instead.

Other Changes

  • Slimmer and faster JavaScript strings in Firefox. Mozilla has optimized how Latin1 strings are stored in Firefox bringing the requirements down from two bytes to 1 byte. This can save memory on websites as Jan de Mooij points out.
  • Support for connecting to HTTP proxy over HTTPS added. Check out the bug on Bugzilla for additional details.
  • New Content Security Policy backend. You can read more about that on Bugzilla.
  • Azerbaijani [az] locale added

Developer Changes

  • DOMMatrix interface implemented
  • WebCrypto: RSA-OAEP, PBKDF2 and AES-KW support, wrapKey and unwrapKey implemented, Import/export of JWK-formatted keys
  • Event listeners popup. Ev icons show up in Inspector which you can click on to display a list of event listeners attached to the element.
  • New @media sidebar which displays all @media rules and shortcuts to them in the stylesheet.
  • Right-click to add new rules in the Inspector.
  • @keyframes rules are now displayed in the Rules section of the Inspector.
  • Cubic Bezier Editor added.
  • You can hover over any transform CSS property in Inspector to display its original position and see how it transformed.
  • You can disable cache in the settings tab and the selection persists now.
  • Three new commands have been added to the Developer Toolbar: inject, highlight and folder. Inject to inject jQuery or JavaScript libraries into a page, highlight to highlight all nodes matching a selector, and folder to open a directory on the system.
  • WebIDE has landed but it is not enabled by default. To enable it toggle devtools.webide.enabled on about:config.

Unresolved issues

  • When you are using pdf.js, Firefox's built-in pdf reader, you may get wrong colors on some images.

Firefox 33 for Android

firefox 33 android

Some features that landed in the desktop version of Firefox landed in the Android version as well. This includes JavaScript string improvements and the new CSP backend.

  1. Firefox supports sending videos to Chromecast or Roku devices now.
  2. A new option has been added to clear browsing data when the browser is closed. To enable it tap on the menu icon in the top right corner and select settings from the context menu that opens up. Select privacy in the settings window and check the option "always clear when quitting". This opens a customization menu to select the items that you want deleted on exit.
  3. Tab management improvements: list recently closed tabs, close all tabs at once, tab quick switching and undo closed tabs.
  4. Locales added: Aragonese [an], Frisian [fy-NL], Kazakh [kk] and Khmer [km]

Security updates / fixes

Security updates are published after the release of Firefox. We will add those once they become available.

Additional information / sources

This article was first seen on ComTek's "TekBits" Technology News


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