Firefox & Browser Compatibility Testing

Even though it has lost significant market share to its closest competitor, Google Chrome, Mozilla Firefox is still way ahead in market share when compared to other browsers like Safari and Edge. That is one of the main reasons why even the Chrome loving developers perform cross browser testing in at least Firefox first before delivering any piece of web code.

Mozilla Firefox and Google Chrome are the world’s most used web browsers. Yet that was not always so. In the past, Firefox has been the most used browser by a very significant margin. Firefox project and the Mozilla foundation has been a beacon of open source success and a trendsetter of browser technology. The open-source initiative has locked horns with the largest tech companies in the world and has built up a brand that rivals giants like Google, Apple, and Microsoft in the game.

Firefox leads most of the browsers in terms of performance, usability, community support, and security.

In this post, we are going to discuss why testing on Firefox should be important for you, where it is incompatible compared to other major players.

History of Mozilla Firefox

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Firefox, also recognized as Mozilla Firefox is a free and open-source web browser, developed by a not-for-profit organization Mozzila Foundation which is dedicated to open source initiatives. Its story starts in 1998 when an American internet services provider company Netscape Communications Corporation decided to design and launch a user-friendly browser christened as Netscape Navigator. The Navigator was succeeded by Netscape Communicator and the source code of Communicator 4.x was the base of both Mozzila Application suite and its spinoff which will be known eventually as Mozilla Firefox.

The idea behind the development was to build a light and fast-loading web browser that would appeal to users efficiently. Later In 2002, the company released its first browser, Phoenix, which provided features such as bookmark for saving multiple Website addresses and the ability to add various extensions to customize the browser. Due to the trademark related issues, the name was changed to firebird then ultimately to Firefox.

The first version of Firefox Firefox 0.8 contained an installer for Microsoft Corporation’s Windows operating system and Google as its default search engine, however other search engines could also be used accordingly by the users. After the release of Firefox 1.0, Mozilla took a significant portion of the market share even when Microsoft’s Internet Explorer had just been launched. Later, the company expanded worldwide its business with its availability in more than available 31 languages.

After the creation of an open community, the Mozilla project had become larger than anytime before. Members of its community started to expand the scope of its products’ real aim rather than focusing on the subsequent browsers of the Netscape series. They started creating multiple browsers of a variety, different development tools and a wide range of other projects. They contributed to Mozilla by different ways and developed a number of open-source software with various features.

In 2002, more than 85% of Internet users were using Internet Explorer for web browsing. However by 2009, even amid intense competition by Microsoft backed IE, the usage share of IE fell to 66%, with Firefox scooping up 25% of the market peaking at a market share of 32% in 2010.

Though the usage numbers have declined significantly since then thanks to the meteoric rise of Chrome, Firefox is still a major contender in the market and a favorite among lots of developers and tech enthusiasts.

Browser Market Share of Firefox

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Now the most important question is, how popular is Firefox browser right now and how important it is for you to test on Firefox browsers.

Well, the hard truth is that even though Firefox used to be a favorite browser once upon a time, it has significantly lost it’s earlier market share to Google’s Chrome browser.

Firefox is used by around 10% of the desktop audience worldwide, however, it is still the second most used browser after Chrome. It is more popular than Safari and Edge, the default browsers that come with the latest Mac and Windows machines.

If we look at the fact that there are more than 3.9 billion internet users worldwide, just 10% of that number becomes somewhere around 390 million potential users. At that scale, you can start to see the picture on how many potential users/customers you may lose if your website is not cross browser compatible with Firefox.

Taken in that perspective Firefox suddenly becomes more important doesn’t it!!

However there is more complexity involved when we take into picture the target audience as well. For example if your website or web business is targeted more towards tech savvy users, then there is a high probability that your website would be getting much more than 10% traffic from Firefox.

A good way find which browsers are more important for you would be to check your web analytic’s technology sections. For example if you are using Google Analytics, navigate to Audience -> Technology -> Browsers & OS. This will help you understand how much traffic is coming from which browser.

  • What is inside of a Firefox browser
  • How does it work and what it does differently than other browsers
  • History of FF
  • Its layout engine – gecko for <57 and Quantum for 57+ –
  • Why this change in layout engine was required –
  • Why you need to test on both 57+ browsers and browsers lower than 57 because of this
  • What are the features that are available only in firefox browsers
  • Platform Availability
  • Market adoption (ofcourse)
  • Different builds of Firefox (maybe)
  • Firefox development cycle
  • Using firefox with selenium
  • Drivers required, what’s in the driver,
  • Why scripts may work with chrome but not with firefox
  • CAN I USE breakdown of FF

Platform Availability

The desktop version of Firefox is available and supported on Microsoft Windows, macOS and Linux, though Firefox for Android is separately available for Android operating system. Firefox desktop should be installed in a system meeting minimum requirements for best performance.


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Operating Systems (32-bit and 64-bit)

  • Windows 7, Windows 8, windows 10

Hardware Requirements

  • Pentium 4 or newest processor that can support SSE2
  • 512MB of RAM / 2GB of RAM for the 64-bit version
  • 200MB of hard drive space


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Operating Systems

  • macOS 10.9, macOS 10.10, macOS 10.11,macOS 10.12, macOS 10.13

Hardware Requirements

  • Macintosh computer with an Intel x86 processor
  • 512 MB of RAM
  • 200 MB hard drive space


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GNU/Linux distributors can provide packages on the basis of different system requirements.

Software Requirements

Firefox runs within the following compatible libraries or packages :

  • GTK+ 3.4 or higher
  • GLib 2.22 or higher
  • Pango 1.22 or higher
  • Org 1.0 or higher (1.7 or higher is recommended)
  • libstdc++ 4.6.1 or higher

For optimal functionality, following libraries or packages should be utilized :

  • NetworkManager 0.7 or higher
  • DBus 1.0 or higher
  • GNOME 2.16 or higher
  • PulseAudio

Browser Compatibility Issues

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Though Firefox has maintained a sustainable growth with its compatibility on different platforms and environments, its latest version faces several incompatibilities like CSS Reflections, CSS image-set, CSS Cross-Fade Function, Filesystem & FileWriter API and Speech Recognition API. There are also several partial compatibilities like CSS scrollbar styling, :matches() CSS pseudo-class, and CSS Appearance.

As web-based platforms are not merely an online visiting card for e-commerce businesses, but also a primary source of revenue in these days. Developers have a major challenge to count different ways to get to a website running on different types of devices and web browsers. Experts engage to moderate the website needs to ensure an independent approach of leveraging internet facilities. User expects to have a good experience on website. Cross Browser testing allows developers to realize how better a company’s website or web application performs across different browsers which are not same to each other as per the specifications.

Cross browser testing facilitates developers to refine bugs and eliminate usability issues before a website becomes available on server. This can also be ensued on regular time-intervals. The users might be using any of these web platforms such as Mozilla Firefox with Windows 10, but it is indulged potentially on Windows 8.1 or Windows 7. Organizations need to ensure an operational strategy for their websites, where they are loaded to perform across different web browsers. However cross browser testing ensued on a regular basis can be an effective aid to rectify such issues. offers several advantageous tools to perform cross browser testing for your website or web application’s interoperability across different platforms. It is also a powerful tool used to examine your website or web application’s bugs and deficiencies. Cross browser testing can be accomplished with the help of efficient environments, starting from Macs to iPhones and Androids. While investigating the website with thorough measures, several process-reports are observed. This can work closely with automated testing and can also be performed on a regular basis.

A sustainable organization develops a mechanism to support and help more customers with an aim-oriented mission. In the same sequence, Mozilla followed this model to create an open and collaborative environment to use the internet freely.