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Mozilla Firefox


Quick Specs

  • Version:
  • Total Downloads:
  • Date Added:
    Jun. 21, 2011
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  • Product ranking:
    #1 in Web Browsers

Editors' Review


The bottom line: Firefox 5 is a worthy expression of Mozilla's ideals. The browser is competitively fast, sports a new minimalist look, and includes some excellently executed features. Unfortunately, that describes most of Firefox's competition, too.

Firefox 5 is the first version of Firefox released under Mozilla's rapid-release cycle, which means that instead of seeing a new whole-number version once every year or two, you'll now see one every three months. This follows in the footsteps of Google Chrome, which adopted the rapid-release cycle a while ago and is now up to version 12 (at the time this review was written) despite having its first release only in 2008.

Firefox 4 had a massive impact on Firefox 5, and so this review is not dramatically different from its predecessor. Firefox 4 had a rough time in its early development, but those days are over. The browser that you can download now is in the same speed category as its competition; offers many similar features (stronger in many areas and slightly weaker in others); includes broad, cross-platform support for hardware acceleration and other "future-Web" tech and standards; and is a must-have for Android users (download for Android).

In Firefox 5, you get more incremental updates that generally focus on making the browser work better. One of the most important improvements is that the browser now supports Mozilla's new Add-on SDK, formerly called Jetpack. This foundation lets programmers build extensions out of Web technologies such as HTML, CSS, and JavaScript rather than the older XUL technology. Extensions are expected to be easier to write and ought not to break when new browser versions arrive, although add-on developers must still decide whether to rewrite their existing extensions. The browser supports Mozilla's new Add-on Builder, too, which ought to make it easier to create add-ons.

Also under the hood, CSS animations now work in Firefox 5, which means that the browser can handle more dynamic Web content that moves around a page more easily.

Not much of the interface has changed from Firefox 4, although the Do Not Track box has been moved to a more prominent place in the Options menu, under Privacy. It's also now available in Firefox for Android.

It's important to point out that there are four versions of Firefox available at the moment, and this review only addresses the "stable" branch, intended for general use. Firefox's other channels are Firefox beta (download for Windows | Mac | Linux); Firefox Aurora, analogous to Google Chrome's dev channel (download Aurora for Windows | Mac | Linux); and the bleeding-edge, updated-nightly Firefox Minefield (download for all versions) are respectively progressively less stable versions of the browser, and aimed at developers.

Please note that the First Look video below is still applicable to Firefox 5, as is these Firefox 4 How To collection, even though they feature Firefox 4.

Installing Firefox 5 was a fine, quick experience. Firefox 4 beta users will find themselves still in the beta channel, which is currently on version 5. If you were testing Firefox 4 beta and hoped that the update to Firefox 4 stable or Firefox 5 stable would clean up the 10 months' worth of beta detritus, which created a new track for each version, you're out of luck. That's the cost of using a beta.

We mistakenly reported that Firefox 4 didn't include automatic updating the way that Chrome and Opera do. In fact, it did, as does Firefox 5. Firefox 5 has gotten significantly faster at restarting, and the process that used to take several minutes took less than 1 minute on our test computers. If you're updating from version 3.6 to version 5, the process is likely to take several minutes because of the significant code changes that have been made.

Careful Firefox observers will notice that the browser no longer ships with a separate icon for Safe Mode. Simply hold down Shift; when you click on the Firefox icon to open a box you will be allowed to customize which settings carry over to Safe Mode.

Firefox automatically installs a Windows 7 taskbar icon if you choose it as your default browser. Uninstalling the browser does not leave behind any icons or folders if you choose to remove your settings at the same time.

If you're a big Firefox fan, you'd better hope that either you're not very attached to the version 3.6 look or you're extremely taken by the new design. The main interface is now completely different from what's come before, retaining only the larger back button that debuted in version 3. Not surprisingly, the new design also brings the browser significantly closer to the minimalist style first adopted by Google Chrome in 2008, although it looks most similar to Opera 11.

The menu bar has been squished into an orange button on the upper left, with menu options spread across two columns. Nearly all the submenus have been redesigned as well, although the hot keys remain the same, so the learning curve isn't particularly steep. In fact, the menu redesign makes it much easier to get to bookmarks, add-ons, and history, as they now all live on one menu pane. The menu button is not available to Mac users, to keep with the Mac OS X theme.

Besides the major changes to the menu, smaller changes have greatly improved usability. For example, there's now a Get Bookmark Add-ons link in the Bookmarks submenu. The History submenu now has Recently Closed Tabs and Recently Closed Windows sections.

Tabs are now on top by default, and while the forward and back navigation buttons haven't moved, the stop and refresh buttons are now attached to the right side of the location bar, next to the bookmark star. When you're typing a URL, the "Go" button appears in green. While resolving a URL, the box changes from the "Go" arrow to an "X" for the new Stop button, and the green changes to red. The visual cues are minor but help to highlight their new location in the interface. Returning the Stop and Refresh buttons to their Firefox 3.6 locations can be done via the Customize option. What little color remained in the default interface, mostly the green Back button, has been leeched out for a muted gray. You can customize the Firefox skin with the restartless Personas add-ons, added in Firefox 3.6.

Right of the location bar lives the traditional search box, with its drop-down list of search engines. Above that on the tab bar there is a new button that lists all your open tabs, and you can add a button to access the Tab Groups feature. If you don't see the button, you can add it by right-clicking on the interface and choosing Customize, then dragging and dropping the Tab Groups icon next to the List All Tabs button. We don't consider many customizations to be essential, but this one is.

The Status bar that lives at the bottom of the interface is now hidden by default, again in keeping with the minimalist philosophy and the competition. There's a new Add-on bar as well, also hidden by default, to which extension icons can be added if you want to keep add-on icons easily available but out of the way of the main interface.

One of Firefox's singular strengths is its capacity for customization, which remains unparalleled and which is accessible even to novice users. While the competition does offer add-ons and extensions, Firefox remains far ahead of all of them in interface customization.

Features and support
Firefox 5's features are robust and generally competitive. There is some minor functionality missing in a few cases where the browser remains behind the competition, but Firefox is generally one of the most progressive major browsers available, an early adopter if not always an innovator.

The most important feature in Firefox 4 and 5 is Sync. As with many recent Firefox features, it started off as a rough add-on, and often deleted data. If you were scared off by its early bad behavior, you'll be glad to know that Mozilla has worked out the kinks since version 4. Sync now smoothly syncs your Bookmarks, Passwords, Preferences, History, and Tabs not only with other computers, but also with your Android version of Firefox.

To use it, click on the Menu button and choose Set Up Sync from the left column. That will take you to a window where you can connect an existing Firefox Sync account or create a new one. Within Firefox Sync, there are two important security points. One is that Firefox encrypts your data before sending it over an encrypted connection to its servers, where it remains encrypted. Mozilla says that the company would not be able to access it even if somebody there wanted to. The second is that you have the option of setting up your own personal sync server. In an age when private data stored by corporations gets hacked and stolen with shocking regularity, setting up a personal sync server is one way to ensure that you bear the responsibility for your own data.

Another big feature in Firefox 5 is support for restartless add-ons. These add-ons are written differently from standard Firefox add-ons, and are expected to become the format for add-ons in the future. As such, not many restartless add-ons exist--only about 250 at the time of writing this review, compared with the thousands of "standard" add-ons. However, this is an improvement of more than 100 add-ons since Firefox 4 debuted in March 2011. Add-ons continue to pose a big problem for Mozilla, as older add-ons become a bottleneck for Firefox that other browsers, with their newer add-on frameworks, don't have to manage. The aforementioned Add-on SDK is designed to confront this problem directly.

Firefox 4's add-on manager was completely overhauled, and the Firefox 5 add-on manager continues to tweak its landing page. There's a lot of useful new technology here, as compared with the version 3.6 manager. Not only can you search for add-ons from within the add-on window using the search box in the upper right corner, you can add them without having to jump to the external Mozilla Add-on Web site, also known as AMO. The manager calls out the AMO add-on collections, which you can create more explicitly in the Get Add-ons tab. The add-on manager also allows you to browse Personas. It's slightly annoying that clicking on an add-on group or collection opens the page in a new browser window, whereas clicking on a specific add-on opens that add-on's download page within the add-on manager. That's a very minor criticism, though.

Other changes to the add-on manager include forward and back buttons specific to the manager, in the upper left corner, and left-side navigation tabs for specifically focusing on Extensions, Appearance, and Plug-ins. Meanwhile, two little improvements to the manager will impress keyboard junkies. There's a new hot key for pulling up the add-on manager, Control-Shift-A, and you can type "about:addons" directly into the location bar to access the add-ons manager in a tab.

The tab-grouping feature seems to be suffering a bit of an identity crisis, though its functionality is unchanged. Originally called Tab Candy, then renamed Panorama, and now known as Tab Groups, it presents your tabs as an array of thumbnail images. The thumbnails reside in rectangular boxes that constitute a group. Tabs can be dragged from one group to another, and groups can be named and moved as well. You can add a tab to an existing group or create a new group by right-clicking on the tab and choosing Move to Group. The hot-key combo Control-Shift-E will also jump between the main interface and the Tab Group window.

The overall idea is to make it easier to switch from one tab to another, to group or regroup related tabs, and to get a global view of what's going on with your tabs. It's potentially a big improvement in browser usage, compared with aiming a mouse at an ever-skinnier tab, cycling through a list with Alt-Tab keystrokes, or pecking at a drop-down menu to reach the tabs that overflowed off the deep.

The bookmarks and history menus have been redesigned, and now the hot keys open them by default as sidebars. Go through the Menu button to get the full menus. We were actually quite impressed with the layout of the menu button options for bookmarks and history, finding it much more useful with quick access to recently closed tabs and new bookmark tags. This is probably the most useful in-browser bookmark manager around, especially if you enable Sync and use it with your Android phone or tablet.

Firefox 5 supports App Tabs, which reduces the width of a tab to its favicon and pins the tab permanently on the left. The tab will glow when updated, a useful indicator for things like Web mail. And when you start typing into the location bar, one of the search choices will be related open tabs so that you can quickly switch to an existing tab.

Under the hood there are tons of changes. The biggest is full hardware acceleration across all platforms, which means that Firefox draws on your graphics card to speed up complex rendering. You'll see dramatic HTML5 support, including for high-definition WebM video, and broad support for the HTML5 canvas, video, audio, geolocation, drag and drop, and form tags. OpenType fonts are supported, as are CSS3 and newer JavaScript values. WebGL and hardware acceleration give the browser a massive boost, which we'll discuss in the Performance section below. The short version of all this is that Firefox 5 is on the cutting edge of the next generation of Web standards, and that benefits you immensely by offering faster rendering times of Web sites that can do more.

There's a decent list of other, smaller changes to Firefox that are worth pointing out because they'll enhance your work flow in the browser. One of these is Switch to Tab. Open a new tab, start typing the name of an already-open tab, and the URL will appear in the drop-down with "Switch to Tab" beneath it. Select that one, and the new tab closes and you're whisked to the preexisting tab. It's a great trick for cutting down on the amount of time it takes to sift through 45 open tabs, and removes the chance of accidentally having the same tab open twice or more.

The location bar, or as Mozilla calls it, the Awesome Bar, retains the features introduced in Firefox 3.5, such as the options to search your history and bookmarks and to tap your default search engine to provide you with quick results. However, the "feeling lucky" instant jump to what it thinks is the Web site you're most likely to be looking for has been disabled because of internal Mozilla concerns about accidentally sending personal information to the search provider.

Private browsing reflects the browser's faster start-up and shutdown times so that it jumps between standard browsing and Private Browsing mode significantly faster than in version 3.6.

The new Do Not Track feature indicates via a header notification that you want to opt out of targeted advertisements. However, it requires that the Web site you're viewing, and therefore that site's developers, respect the header itself. While this is great for future-proofing the Web, as implemented at the time of writing, not many Web sites have taken notice of it. While that doesn't mean it won't eventually have a big impact, that time is not now, and it's better to install an add-on like Adblock Plus to get more complete ad-tracking protection.

There are two smaller yet important changes to the way that Firefox protects you. One is the implementation of the Content Security Policy, which is designed to block one of the most common types of browser threats, cross-site scripting attacks, by allowing sites to tell the browser which content is legitimate. Though CSP also places the burden on the sites' developers, it's backward-compatible and aimed mostly at well-known sites hosting immense volumes of data and content.

Another security improvement is the implementation of HTTP Strict Transport Security (HSTS). This prevents your log-in information from being intercepted by telling Firefox to automatically create a secure connection to a site's servers.

The new feature set alone makes it worth upgrading to the latest version of Firefox. While some older Firefox users may feel that these features add unnecessary bloat to a browser that offers add-ons specifically so that you can customize your browsing experience, Firefox 4 was actually dramatically faster than Firefox 3.6, and Firefox 5 continues to perform well. We address the browser's behavior in the section below.

As mentioned earlier, Firefox 5's performance has been greatly improved by the addition of graphics processing unit (GPU) hardware acceleration. It allows the browser to shove certain rendering tasks onto the computer's graphics card, freeing up CPU resources while making page rendering and animations load faster. These tasks include composition support, rendering support, and desktop compositing.

JavaScript plays a major role in the Web, and Firefox 5's JaegerMonkey engine combined with the GPU acceleration gives the browser some serious juice. For a full rundown on Firefox 4 versus Chrome 11 versus Internet Explorer 9, check out our most recent browser benchmark battle. The short version: Firefox 4 came out on top. However, because of ongoing improvements made in the browser space, especially to Firefox and Chrome, it wouldn't be surprising to find that the browsers all test extremely close to each other.

One interesting publicly available benchmark is the new JSGameBench from Facebook, which looks to test HTML5 in real-world gaming situations. JSGameBench hasn't posted new results since April 2011, but the ones it did gave strong marks to the Firefox 4 beta both with and without WebGL. The stable version of Firefox 4 also did well in JSGameBench tests once it was released.

Note that to effectively use hardware acceleration, you must make sure that your graphics card drivers are up-to-date.

Browser benchmarks are a notoriously fidgety lot, and often come up against legitimate complaints that they look at too narrow a set of features--such as checking only JavaScript rendering times. In hands-on use, at least, Firefox 5 can more than hold its own. It's not clear that it's enough to counter the past two years of Chrome decisively winning the fastest-browser PR campaign, but that may no longer be the point. All five major browsers are now similarly fast at JavaScript tests, and you may start looking at other criteria to determine which browser is best for you.

In hands-on experiences, one of the best performance differences between Firefox 3.6 and the current version is that Firefox 5 crashes far, far less. That's due in no small part to improvements made to the plug-in crash protection, which prevents plug-ins like Adobe Flash, Apple QuickTime, and Microsoft Silverlight from dropping the browser dead. If one of them crashes, simply reload the page. And while there had been a vocal minority suffering from memory leaks in Firefox 4.0.1, a fix for that particular bug was issued in version 5 and it's not expected to be a continuing problem.

Definitely a worthy heir to the Firefox name, Firefox 5's one drawback is that, like its competitors, it uses massive amounts of RAM. Don't expect that to change as the browser is relied upon to perform more and more tasks that once occurred in other programs. It will also be less of a problem as hardware improves.

Firefox 5 faces a challenging field of competition. Some people have probably abandoned the browser for the significant speed differences between version 3.6 and Google Chrome. However, the competition has forced Mozilla and others to put out better browsers in order to thrive, and we think that Firefox 5 will keep the browser competitive.

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Publisher's Description

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User Reviews
  • Current Version


    out of 167 votes

    • 5 star 55
    • 4 star 44
    • 3 star 30
    • 2 star 17
    • 1 star 21
  • All Versions


    out of 15646 votes

    • 5 star 10327
    • 4 star 2431
    • 3 star 993
    • 2 star 667
    • 1 star 1228
  • My rating

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Results 1–10 of 167

3 stars

"Hey - it's free and it works better than IE"

August 15, 2011  |  By venn

2011-08-15 16:28:15  |  By venn

 |  Version: Mozilla Firefox 5.0


The ability to have add-ons. It works as IE 9 doesn't seem to.


It seems more unstable than previous versions, so it often seems to struggle to launch. Tabs I have closed are showing up when I launch the program again-I thought it used 2 ? if I wanted 2 keep the webpages I had open before I closed the browser.


It is was I consistently use as there are add-ons that I need and love AND b/c it works better than other browsers, but I am a little disappointed in its functionality over the versions.

Updated on Aug 15, 2011

It is what I consistently use as there are add-ons that I need and love AND b/c it works better than other browsers, but I am a little disappointed in its functionality over the versions.

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5 stars

"Tried them all, and Firefox is my favourite"

August 14, 2011  |  By Bensubaru

2011-08-14 08:45:42  |  By Bensubaru

 |  Version: Mozilla Firefox 5.0


The best web browser available in my opinion.
Great design.
Fast and easy to use.


Takes AGES to launch!


I've tried every web browser, and Firefox is easily my favourite. Love it.

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5 stars

"best for now"

August 14, 2011  |  By alfiaqil

2011-08-14 01:27:39  |  By alfiaqil

 |  Version: Mozilla Firefox 5.0


free and many function


so many add-on make more slow in progress

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3 stars

"It's OK.... just that...."

August 13, 2011  |  By ZRMaster

2011-08-13 03:11:32  |  By ZRMaster

 |  Version: Mozilla Firefox 5.0


New interface...
Security fixes...


How long does your Firefox starts?
More you install addons slower it becomes...


Task manager process test: (Windows XP SP3)
Firefox 5.0 ---> 200 MB
Internet Explorer 8.0 ---> 70 MB
(with just one same web page opened)
Judge yourself......

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4 stars

"Sucks the memory"

August 08, 2011  |  By muhammed78

2011-08-08 14:46:48  |  By muhammed78

 |  Version: Mozilla Firefox 5.0





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1 stars

"WHAT A P.O.S!!!"

August 07, 2011  |  By maddogz06

2011-08-07 18:49:00  |  By maddogz06

 |  Version: Mozilla Firefox 5.0


None that I can find!


Buggy, crashes, locks up when launched, incompatible with essential plug-ins and add-ons.


If I ever delivered a program this bad to a client, I would be fired immediately. It is TOTALLY inexcusable the Firefox 4 and now Firefox 5 are so unstable. I depend on my PC tools to make a living. If it NOT my job to re-learn something that I already know quite well just because a developer at Mozilla decides to change the look and feel of the product. It is the Mozilla developers job to accommodate users, not the other way around. If the user community at large is clamoring for a new look and feel, at least have the decency to provide a compatibility mode for those of us that DO NOT want the new look and feel. Also, why is it that with each new release of Firefox, my essential plug-ins and add-ons no longer work? Is there a VALID reason for changing the plug-in and add-on interfaces? At this point, I have given up and started using Chrome. This is not my first choice, but at least Google seems to be staffed by professionals!!!

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3 stars

"FF hasn't been as stable since version 3.6.x"

August 06, 2011  |  By pentium4forever

2011-08-06 08:22:32  |  By pentium4forever

 |  Version: Mozilla Firefox 5.0


Free and works well most of the time but has become more unstable since version 3.6x


Freezes a bit with extensions that never had issues with it in older versions, perhaps it's a development problem. Flash crashes a bit and doesn't always work well. This is coming from a longtime FF user.

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5 stars

"Firefox is number 1"

August 05, 2011  |  By tgho2

2011-08-05 18:49:10  |  By tgho2

 |  Version: Mozilla Firefox 5.0


Fast, Secure, Good Design, A Great App Called, Adblock Plus to block ads, runs perfect(on windows 7)


Nothing is bad nothing to worry about(on Windows 7)

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5 stars

"Still the Best"

August 05, 2011  |  By Ken_Saunders

2011-08-05 07:40:13  |  By Ken_Saunders

 |  Version: Mozilla Firefox 5.0


It's snappy, loads pages fast, very secure, the most customizable browser available, provides the ability to add and change advanced settings, and Firefox provides excellent accessibility features for individuals with disabilities.


There isn't a Firefox OS


I have gotten more out of using Mozilla Firefox in the past 6+ years than I have from any other piece or type of software, ever. Even OS's.

Mozilla has consistently delivered a solid, safe, and very fun to use product from day one, and I expect nothing less from them in the future.

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3 stars

"Easy to use"

August 04, 2011  |  By eunomia

2011-08-04 21:16:42  |  By eunomia

 |  Version: Mozilla Firefox 5.0


Friendly with user and easy to use.


not right now

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Results 1–10 of 167

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Full Specifications

What's new in version 5.0
Firefox 5.0 includes more than 1,000 improvements and performance enhancements.
Publisher Mozilla
Publisher web site
Release Date June 21, 2011
Date Added June 21, 2011
Version 5.0
Category Browsers
Subcategory Web Browsers
Operating Systems
Operating Systems Windows 2000/XP/2003/Vista/7
Additional Requirements None
Download Information
File Size 41.06MB
File Name Firefox Setup 44.0.exe
Total Downloads 48,877,667
Downloads Last Week 34,339
License Model Free
Limitations Not available
Price Free

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