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Mozilla today launched Firefox 44 for Windows, Mac, Linux, and Android. Notable additions to the browser include push notifications, the removal of RC4 encryption, and new powerful developer tools.

Firefox 44 for the desktop is available for download now on Firefox.com, 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.

Before we dive into the desktop versus mobile breakdown, there is one change that affects all four platforms: The RC4 cipher is no longer supported over HTTPS connections. RC4 is a stream cipher designed in 1987 that has been widely supported across browsers and online services for the purposes of encryption. Multiple vulnerabilities have been discovered in RC4 over the years, making it possible to crack within days, or even hours.

In February 2015, new attacks prompted the Internet Engineering Task Force (IETF) to prohibit the use of RC4 with TLS. Google, Microsoft, and Mozilla all promised to drop RC4 support in their browsers this year. Google delivered last week with Chrome 48, and now Mozilla has made the change with Firefox 44.

If you try to open a website that uses RC4 in Firefox 44, you’ll simply get an error like this:


Microsoft is the last one left to deliver on its promise.


The biggest highlight in this release is the ability to receive push notifications from websites, assuming you give them permission. If this sounds familiar, that’s because Google added such functionality in April 2015 with the release of Chrome 42.

Unlike Firefox’s existing web notifications, you can receive push notifications even when the website is not loaded in a tab. “This is super useful for websites like email, weather, social networks and shopping, which you might check frequently for updates,” Mozilla explained.


As we noted when Chrome gained the functionality, this is a quite intrusive feature for a browser, but just like Google, Mozilla is promising the users have to first grant explicit permission before they receive such a push notification. You can manage your notifications in the Control Center by clicking the green lock icon on the left side of the address bar.

Furthermore, Mozilla is making the following three privacy promises for the feature:

  1. To prevent cross-site correlations, every website receives a different, anonymous Web Push identifier for your browser.
  2. To thwart eavesdropping, payloads are encrypted to a public / private keypair held only by your browser.
  3. Firefox only connects to the Push Service if you have an active Web Push subscription. This could be to a website, or to a browser feature like Firefox Hello or Firefox Sync.


Next up, developers are getting new visual editing tools and memory management tools.


The Page Inspector’s animation panel makes it easy to scrub, pause, and visualize each animation on a webpage. You can switch between a global view of every animation, drill down to just a few nodes, or even pick a specific animation and use the visual cubic-bezier editor to ensure it moves just the way you like. A similar editor for CSS filters allows you to visually add, remove, reorder, and adjust filters with live feedback from the page.


You can now also enable pixel rulers along the page margins and use the new measurement tool to drag-and-measure arbitrary regions of the page. The Inspector now defaults to displaying CSS colors “as authored,” an eyedropper tool lets you pick colors right from the page, and shift-clicking on a color swatch cycles between authored styles and equivalent hex, rgb, and hsl values.


The new Memory tool helps front-end engineers understand and optimize the way pages allocate and retain memory. It takes a snapshot of the heap and allows you to drill down by retained object type, allocation stack, or internal representation. Mozilla told VentureBeat this is just the beginning, so if you want even more granularity — it’s coming.


Here’s the full Firefox 44 changelog:

  • Improved warning pages for certificate errors and untrusted connections
  • Enable H.264 if system decoder is available
  • Enable WebM/VP9 video support on systems that don’t support MP4/H.264
  • In the animation-inspector timeline, lightning bolt icon next to animations running on the compositor thread
  • Support the brotli compression format via HTTPS content-encoding
  • Screenshot commands allow user choice of pixel ratio in Developer Tools
  • Fixed: Windows XP and Vista screensaver doesn’t disable when watching videos (Bug 1193610)
  • Various security fixes
  • To support unicode-range descriptor for webfonts, font matching under Linux now uses the same font matching code as other platforms
  • Use a SHA-256 signing certificate for Windows builds, to meet new signing requirements
  • Removed support for the RC4 decipher
  • Firefox will no longer trust the Equifax Secure Certificate Authority 1024-bit root certificate or the UTN – DATACorp SGC to validate secure website certificates
  • Stricter validation of web fonts
  • On-screen keyboard support temporarily turned off for Windows 8 and Windows 8.1
  • Right click on a logged object in the console to store it as a global variable on the page
  • Visual tools for Animation: View/Edit CSS animation keyframe rules directly in the inspector, Visually modify the cubic-bezier curve that drives the way animations progress through time, Discover and scrub through all CSS animations and transitions playing on the page
  • Visual tools for Layout and Styles: Display rulers along the viewport to verify size and position and use the measurement tool to easily detect spacing and alignment problems, Use CSS filters to preview and create real-time effects like drop-shadows, sepia, etc.
  • New memory tool for inspecting the memory heap
  • Service Workers API
  • Built-in JSON reader to intuitively view, search, copy and save data without extensions
  • Jump to function definitions in the debugger with Cmd-Click
  • WebSocket Debugging API and add-on
  • The rule view now displays styles using their authored text, and edits in the rule view are now linked to the style editor

If you’re a web developer, more details are available for you here: Firefox 44 for developers.


Firefox 44 now supports the Android print service. If you need to print a document on the go, you now have yet another way to do so from your Android phone or tablet.

Here’s the full Firefox 44 for Android changelog:

  • Use Android print service to enable cloud printing
  • Prompt user before opening Intent URIs in a Private Browsing tab
  • Show search history suggestions
  • Web-based Firefox Accounts page
  • Added support for launching URIs with mms: protocol
  • Users can now choose a homepage to display on startup instead of the Top Sites panel
  • Removed support for the RC4 decipher
  • Firefox will no longer trust the Equifax Secure Certificate Authority 1024-bit root certificate or the UTN – DATACorp SGC to validate secure website certificates
  • Improved tabs tray on phones

Mozilla typically releases new Firefox versions every six weeks, and we thus expect Firefox 45 to arrive before mid-March.

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