Mozilla today launched Firefox 47 for Windows, Mac, Linux, and Android. The browser has gained a sidebar for synced tabs from other devices, improvements to YouTube playback and HTML5 support, and is seeing the end of support for Android Gingerbread.

Firefox 47 for the desktop is available for download now on, and all existing users should be able to upgrade to it automatically. As always, the Android version is trickling out slowly on Google Play.

Mozilla doesn’t break out the exact numbers for Firefox, though the company does say “half a billion people around the world” use the browser. In other words, it’s a major platform that web developers target — even in a world increasingly dominated by mobile apps.


The biggest highlight is a new sidebar for synced tabs. If you’re logged in with your Firefox Account, the sidebar will show all your open tabs from your smartphone and other computers. The sidebar even lets you search for specific tabs.

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Next, Firefox 47 supports the open source VP9 video codec on machines with powerful multiprocessors. VP9 is the successor to VP8, both of which fall under Google’s WebM project of freeing web codecs from royalty constraints.

This means an improved video experience on YouTube, including smoother playback, less bandwidth used, and improved battery life on laptops. YouTube’s implementation of HTML5 uses the VP9 codec, which Google says gives users higher quality video resolution with an average bandwidth reduction of 35 percent.

Here’s the full Firefox 47 changelog:

  • Support for Google’s Widevine CDM on Windows and Mac OS X so streaming services like Amazon Video can switch from Silverlight to encrypted HTML5 video.
  • Enable VP9 video codec for users with fast machines
  • Embedded YouTube videos now play with HTML5 video if Flash is not installed.
  • View and search open tabs from your smartphone or another computer in a sidebar
  • Allow no-cache on back/forward navigations for https resources
  • Latgalu [ltg] locale added. Wikipedia tells us there are 164,500 daily speakers.
  • Various security fixes
  • FUEL (Firefox User Extension Library) has been removed. Add-ons relying on it will stop working.
  • The browser.sessionstore.restore_on_demand preference has been reset to its default value (true) to avoid e10s performance problems. Because faster is better!
  • The Firefox click-to-activate plugin whitelist has been removed.
  • Web platform changes
  • View, start,and debug registered Service Workers in the Service Workers developer tool
  • Simulate Push messages in the Service Workers developer tool
  • ‘Start’ button for service workers in about:debugging to start registered Service Workers
  • Changes that can affect add-on compatibility
  • Added support for ChaCha20/Poly1305 cipher suites
  • Custom user agents supported in Responsive Design Mode
  • Smart multi-line input in the Web Console
  • cuechange events are now available on TextTrack objects
  • WebCrypto: PBKDF2 supports SHA-2 hash algorithms
  • WebCrypto: RSA-PSS signature support

If you’re a web developer, more details are available for you here: Firefox 47 for developers.


Firefox for Android has a slew of minor but notable improvements. The biggest is the removal of the icons that show up in the URL bar.

For many this will be a backtracking, but Mozilla insists it’s a necessary security move. It prevents unsecured sites from copying the images of legitimate sites to trick users into thinking the site is safe for sensitive information.


Next up is a feature that lets you show or hide web fonts. The goal is to reduce bandwidth usage for those with data limits.

Firefox 47 is also the last version to support Android Gingerbread (versions 2.3 through 2.3.7). To be clear, Firefox still works on Android Gingerbread devices, but they simply can’t upgrade past Firefox 47. Android Honeycomb support was dropped after the release of Firefox 45.

Here’s the full Firefox 47 for Android changelog:

  • Add “Show/Hide web fonts” in advanced settings to reduce bandwidth and data
  • Last release to support Android 2.3.x (Gingerbread)
  • Stopped data usage when Firefox is in the background and a page uses meta refresh
  • “Open multiple links” setting under “Customize” has been renamed to “Tab Queue”
  • Remove support for Android web runtime (WebRT)
  • Remove Favicons in Awesomebar to prevent HTTPS spoofing
  • Web platform changes
  • WebCrypto: PBKDF2 supports SHA-2 hash algorithms
  • WebCrypto: RSA-PSS signature support

Mozilla releases new Firefox versions every six to eight weeks, and Firefox 48 is currently slated for early August.

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