Firefox is an open-source web browser produced by the Mozilla Foundation. It’s the major browser using the Gecko rendering engine, and has a number of features that make it more privacy-focused than, say, Chrome. It rose to prominence over the mid- to late 2000s as a superior browser to the stagnant Internet Explorer 6, and peaked at 32% market share in November 2009. Sadly, its fortunes declined as Chrome rapidly surged in popularity, and as of December 2021 it stands at 8% market share on computers, and 4% market share across all devices.

Firefox is almost certainly the web browser I’ve used more than any other; I used it almost exclusively between 2004–2009 (having used Mozilla Suite for years before that), cycled back and forth between it and Chrome between 2009–2012, and switched back to Firefox full-time in 2017. At time of writing, I’ve just started an experiment using Vivaldi as my daily driver, although Firefox is still my default browser on my iPhone. Nonetheless, I still have a lot of attachment to Firefox, I like it, and I want it to take away from Chrome’s mammoth market share.

Here are some of the benefits to using Firefox, especially compared to the other “big four” browsers:

  • uBlock Origin works most reliably in Firefox(external link). Some of the reasons for this include:
    • Firefox ensuring that uBlock Origin has loaded before allowing network connections (Chromium-based browsers don’t wait)
    • Firefox respecting users’ preferences to disable prefetching whereas Chromium allows websites to override user preferences
    • Firefox allowing extensions to block HTML elements before the page has been parsed by the browser, unlike Chromium
    • uBlock Origin having the ability to “see through” CNAME cloaking on Firefox (basically, where websitewithads.com decides to set a CNAME record directing ads.websitewithads.com to spammyadserver.com in order to disguise ads as first-party content to try and thwart ad blockers
  • Firefox has various built-in settings restricting advertisers’ ability to track you, be it via third-party cookies, “supercookies”, or fingerprinting. (Not all these settings are on by default though, as they can break some websites.)
  • The Mozilla Foundation (the non-profit that the Mozilla Corporation are a for-profit subsidiary of) are strong advocates for net neutrality and open standards for the web – but their advocacy is more influential the more market share Firefox has.

Past Firefox UIs

Firefox has gone through a number of different user interfaces over its time, and it can be fun to reminisce over what they looked like 😃

Cool features that Firefox still has

This section is going to talk about features that are relatively unique, or at least not universal (like, every browser has tabs these days).

  • Multi-Account Containers: This is a huge one. Basically, you can use containers to compartmentalise your browsing, preventing cookies, etc. that are set in one container from existing when you browse in others. One potential use for this is privacy: for example, if you have a “Facebook” container only used for Facebook/Meta sites and a “Google” container only used for Google sites, Facebook and Google’s trackers won’t be able to link your browsing elsewhere on the web back to your accounts on their ser­vers (or at least, not just through your cookies). Another use is to log into multiple accounts on the same site in the same browser session, for example being able to log into two email accounts simultaneously and have both their inboxes open in different tabs. (That is, even if the two accounts are unlinked on the email provider’s end.)
  • Picture-in-picture: Start watching a video, press the button to pop it out, and hey presto, you can keep watching your video in a small window hovering over the top of whatever other window you want to look at.

Cool Firefox features that got taken away

One of the reasons Firefox first rose to prominence is that it had a number of features that really appealed to power users, like tabbed browsing, pop-up blocking, and dev tools. (Not that it necessarily invented these – I believe it was Opera that innovated tabs, for example – just that it popularised them.) When Firefox started losing traction against Chrome, that was also because Chrome had won over power users with its sleeker interface and “better performance” early on.

One of the difficulties I believe Firefox has had since Chrome overtook it in popularity is understanding what type of user it really appeals to. I mean sure, in theory it should appeal to everybody – it’s a functional web browser. But in recent time it seems like they’ve gone out of their way to chase “nor­mie” users, at the cost of pissing off their existing user base. This has mainly taken the form of removing features and options and claiming their existence was “confusing”. Some examples:

  • Tab groups: The main thing that kept me coming back to Firefox between 2009–2012 when otherwise I preferred Chrome (which didn’t keep hanging/freezing on me) was that it made it way easier to manage large am­ounts of tabs with tab groups. For example, when I had a university assignment to get done, I’d make a new tab group with all my research in it, and switch to that group when it was time to buckle down. Unfortunately this feature was removed in version 45 (March 2016).
  • View Image Info: In version 87, they removed the very useful feature to right-click on an image and select “View Image Info”(external link) to, you know… see info about the image (like its dimensions, metadata, alt-text, etc.). They did this because they claimed “the right-click menu was too long” and “it wasn’t used much” (and yet the infinitely more useless “Email Image” was kept) and that there were other, multi-step ways to access the same info (e.g. “View Page Info” then scroll through potentially hundreds of images to find the one you wanted the info of; right-click to “Open Image in New Tab” then right-click again to “View Page Info”; using web developer tools and “Inspect”…). After an outcry they let you re-enable it through about:config in version 89(external link).
  • Live Bookmarks: You used to be able to bookmark a site with an RSS feed, and when that site updated, Firefox would notify you that your bookmark had new stuff to check out. This feature was removed in version 64 (Dec 2018).

One ongoing issue seems to be that they keep pointing to unreleased “tel­e­me­try data” to justify the removal of features that were extremely popular and useful. A possible explanation for this is that power users are more likely to disable telemetry, as it’s perceived as a privacy risk (or even an outright violation by some people…), and then features that are pretty much exclusively used by power users appear to Mozilla like they’re barely used at all and then removed.

Side Projects

Firefox has, at times, dabbled in extra projects that are somewhat incidental to their core project of maintaining a web browser. (Not counting Thun­der­bird in this, which is more of a sibling of Firefox as another direct descendent of the old Mozilla Application Suite.) Some of these are, or have been:

  • Firefox OS: Was an operating system designed for smartphones, with releases between 2013–2015 (around the same time that Windows and Ubuntu phone projects were also underway). A fork of Firefox OS, KaiOS, designed for keypad-bearing feature phones, continues to be maintained and is somewhat popular in India.
  • Pocket: Is a read-it-later service that Firefox integrated into its browser many years ago (somewhat controversially(external link)) and eventually acquired in 2017.
  • Firefox Lockwise: Was a minimalistic password manager. On the desktop it’s literally the same thing as Firefox’s “remember this password for later” feature, but there were apps available for iOS and Android to enable you to autofill passwords on those systems from the same database. For some reason Firefox deprecated the apps in December 2021 and you can’t install them any more.
  • Mozilla VPN/Firefox Private Network: A repackaging/rebranding of Mullvad VPN.
  • Firefox Send: Was an encrypted file-transfer service they shut down in September 2020 after it had been reportedly used to send a lot of mal­ware.
  • Firefox Private Relay: A utility where Firefox will give you disposable email addresses that you can use when shopping from certain places that are gonna sign you up for marketing lists once you’ve bought from them, or when subscribing to newsletters or whatever that you don’t want to just give your real email address.


Unfortunately Firefox is not a perfect company, and has done a number of questionable things (beyond just changes they made to their browser which I covered in my points above). I’m putting this list in reverse chronological order, in the assumption that it’s more useful to put the fresher stuff first.

  • With the release of version 98.0 in March 2022, Firefox’s “What’s new” page (that it takes you to automatically after upgrading) was basically a full-page ad for Disney+, which angered people (especially given Mozilla’s historic opposition to DRM and Disney’s full-throated advocacy for it). The same update introduced changes to the downloads manager which made it easier to download things by accident and harder to control what happens to them if you do.
  • In February 2022, Mozilla announced in a blog post(external link) that they are collaborating with Meta/Facebook on “privacy-respecting” ways for advertisers to get feedback on the conversion rates of their advertising. Fund­a­men­tal­ly the idea seems to be that they would only get this information in aggregate, so couldn’t pinpoint individual users. This was controversial because a lot of people hate all advertising and even more hate Facebook as a company, and don’t want to see Mozilla helping them in any way.
  • In January 2022, Mozilla tweeted out a “reminder” that they accept donations in various forms of cryptocurrency, incurring backlash from a founder of Mozilla and designer of Gecko (see relevant Reddit thread(external link)). After this backlash, they announced a “pause” on the ability to donate crypto to them as they undertake a review (see other relevant Reddit thread(external link)).
  • A lot of people are mad about how high executive pay is compared to other non-profits (e.g. Mozilla’s CEO got paid $2.4 million in 2018) while they also engage in layoff after layoff, shedding technical staff.
  • Firefox has placed links to various sites that are paying them to do so, under various names (“Top Sites”, “suggested links”, “sponsored links”, etc.) – the sites in question will be things like Amazon, Google, eBay, etc. Separately but relatedly, articles can get recommended to you on your New Tab page via Pocket. You can disable both those things, but a lot of people resent that they’re active by default, being basically ads. Others are more understanding, because Firefox needs to make money somehow.
  • It’s pretty common for people to block Firefox’s default telemetry “for privacy” but truthfully I’m not sure this improves privacy in a meaningful sense. I guess it depends on whether you trust Firefox to store, use and delete your data appropriately – if you don’t, then by all means disable it, but at least they’re not a company that profits from targeted advertising like Google. I could understand if the telemetry was chewing up an excessive amount of system resources, and I can also understand the irritation of people who are like, “They just use telemetry as an excuse to get rid of useful power user features!” (and actually agree with them tbh). I just think this one is overblown as a “controversy”.
  • In December 2017, Firefox remotely installed a dubious-looking add-on into unsuspecting users’ browsers as part of a marketing campaign for a TV show called Mr Robot. The mechanism they used to do this was one that described itself in the settings as being for telemetry and genuine research studies – not marketing campaigns – so people were ropeable. See relevant article on CNET.(external link)


Over time a number of browsers have been released which built on the Fire­fox codebase. Some of these are what I’d consider “true forks”, in that they’ve diverged since, while others continue to update their underlying Firefox codebase and just overlay their modifications over the top. This latter category is generally more secure. At any rate, here are some of the browsers derived from Firefox:

  • Pale Moon: Forked from Firefox pre-version 28 (retaining that UI), and has also forked the rendering engine (theirs is called Goanna). It supports NPAPI plugins that are no longer supported by mainline Firefox, such as that required to run Adobe Flash. It is considered inadequately maintained, and therefore insecure.
  • LibreWolf: This is the kind of fork that overlays its own modifications over a relatively up-to-date codebase. They aim to be a more privacy-hardened version of Firefox, with uBlock Origin built in and telemetry removed.
  • Waterfox: Another fork, this one in two versions: Waterfox G (the overlay kind of fork) and Waterfox Classic (which still supports the old XUL architecture, and is considered insecure). In late 2019 it was acquired by a “privacy-focused” advertising company, System1, which is also majority-owner of the StartPage search engine.
  • GNU IceCat: Another “overlay” type of fork of Firefox, maintained by the GNU Project, that removes all non-free code (like certain plugins) and copyrighted branding images.

Historically there was also the Camino browser for Mac OS, which used the Gecko rendering engine from Firefox but embedded it into a Mac-native GUI. It looks like it was pretty cool (and I know some people who’ve sung its praises!) but development became difficult after Mozilla stopped maintaining Gecko as a component that could be used separately from the rest of the Firefox codebase, and the browser was discontinued in 2013.

  1. More screenshots, available on the Mozilla wiki: Firefox 4.0 in Windows (Vista and XP)(external link), in Mac OS X(external link) and in Linux (in a couple of different themes)(external link)↩︎

Did you know? I’ve posted other content tagged ‘Firefox’! If you want to see what else I’ve written on this topic, you can do so here.