Running Chrome Extensions in Firefox: What You Need to Know

Angela Randall 25-08-2015

Very soon, you’ll be able to run all your favorite Chrome extensions in Firefox. This game-changing development is likely to bring about a new renaissance in Firefox users and revolutionize the way extensions are created.


This change was announced as part of a raft of Firefox add-on changes from Mozilla. They are evolving to take advantage of a new era of technology and the current landscape of extension development.


Separate Processes

One of the most important announcements was that Mozilla will be incorporating new technologies like Electrolysis and Servo within Firefox, and will therefore make add-ons faster, safer and separated into multiple processes.

What this means for users is that the browser frame and the tabs are separate processes, and if one tab crashes everything else keeps on working. Brilliant news!

Validated Add-Ons For Firefox

There are also new developments to protect users from spyware and adware. Mozilla will be validating and signing all add-ons starting from Firefox 41 on September 22nd.


The add-on signing schedule is as follows:

  • Firefox 40: Users see a warning about unsigned extensions, but extensions continue to work.
  • Firefox 41: Unsigned extensions will be disabled by default, and signature enforcement can be turned off.
  • Firefox 42 and beyond: This will disable and prevent the installation of unsigned extensions.

It’s expected that Firefox 43 will be released by December 2015, so developers will need to take action quickly to get their add-ons signed.

Developers need to also be aware that the XUL and XPCOM technologies will be deprecated over the next year or so. 

Run Any Extension Using WebExtensions

Mozilla will be implementing the WebExtensions API to make it easier for developers to build extensions across Chrome, Firefox, Opera and Microsoft Edge with minimal changes. The WebExtensions API is largely compatible with Blink, which is how Chrome and Opera extensions are developed.


This also means that extensions written for other browsers will be able to run in Firefox, meaning you will soon be able to use your favorite privacy-friendly browser to run the plethora of amazing Chrome extensions The Best Chrome Extensions A list of only the best extensions for Google Chrome, including suggestions from our readers. Read More available in the Chrome store.

“Extension code written for Chrome, Opera, or, possibly in the future, Microsoft Edge, will run in Firefox with few changes as a WebExtension.” — Mozilla.

Mozilla plan to keep tabs on things though, by ensuring all foreign extensions are validated and signed by Mozilla. Only then will they be available through the developer’s site or the Firefox add-on store as a WebExtension. Keep visiting (AMO) to see new releases.


Developers are being encouraged to start testing WebExtensions straight away, and meanwhile Mozilla are discussing with other browser vendors how they can standardize some of the API even further.


Obviously, this move has upset many developers, but overall it should make life easier for developers of multi-browser extensions and for all users of Firefox.

Reasons to Switch to Firefox

If you’ve been feeling trapped in Chrome I Hate Google Chrome But I'm Trapped In It. Here's Why In the Chrome vs. Firefox war, I'm siding with the Google users. But I don't want to. Chrome is my browser of choice because it has features that I can't live without. Read More , or you’re not sure whether or not you can actually trust Google Using Chrome: Can We Really Trust Google? Why not trust Google? The company knows what they’re doing; clearly Google is trustworthy. Or is it? Read More , you’ll instantly feel relieved about being able to switch to Firefox. If you’re not so sure, consider these points:


You can ease the transition by syncing your browser settings 9 Ways to Sync Firefox and Chrome: Bookmarks, Passwords, and More It's easy to work with two browsers if you keep your data synced. Here are some ways to make Chrome and Firefox work in harmony. Read More before you switch. Once you’ve made the switch, be sure to make Firefox feel like home again Switching From Chrome: How to Make Firefox Feel Like Home So, you have decided that Firefox is the better browser for you. Is there anything you can do to make Firefox less of a foreign environment? Yes! Read More and to adjust Firefox from its default Ultimate Browser Settings: Must-Change Items In Chrome, Firefox, & Internet Explorer Let's take a look at those must-change browser items. Maybe you do the same, or perhaps you think that the settings should be different? Read More browser settings.


What Extensions Are You Waiting For?

Popular Firefox extensions The Best Firefox Addons Firefox is famous for its extensions. But which addons are the most useful? Here are the ones we think are best, what they do, and where you can find them. Read More like DownThemAll and webdev tool Firebug may be huge drawcards for using Firefox already, but what have Firefox users been missing out on? Lots.


Although, Firefox has recently caught up a little, letting users use WhatsApp web, cast to their Chromecasts and mute tabs (with the right extension).

Still, many more apps are being developed for Chrome at the moment than for Firefox. What is the first Chrome extension you’ll want in Firefox? Tell us!

Related topics: Browser Extensions, Google Chrome, Mozilla Firefox.

Affiliate Disclosure: By buying the products we recommend, you help keep the site alive. Read more.

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  1. DO
    November 17, 2017 at 12:14 pm

    We need a chromecast extension asap!!

  2. cd
    May 10, 2017 at 10:14 pm

    Am having terrible problem with some script running in FF which flickers the screen every few seconds plus that infamous circle keeps running all the time only stopping for a second or two when there's opp to click something. If you don't catch it in those 2 seconds, you must wait more minutes until the next opp. Staring at the screen!

    I saw on the Mozilla site that one solution is to get rid of any Chrome extension. HOW do I know which are Chrome Extensions??? That is the main question at this point. I have found how to open FF in safe mode without booting it up (if I boot it up I'll NEVER get to the Extension page!).

    How can I get a list of those Chrome extensions? Then I can check them against what I have installed and get rid of them!

  3. Anonymous
    February 25, 2016 at 12:09 pm

    ( I Forgot To Add This In My First Post )

    I Would Love It The Other Way Around, Too - Running FF Extensions Inside CHROME.

    For Any Extension Junkie, FEBE Is A Must Have Extension For FF.

    I Would Love To Have A Similar Extension For CHROME.


  4. Anonymous
    September 18, 2015 at 5:30 am

    Mozilla has not yet provided support for Native calls. My plugins make use of XPCOM and I need to make native calls to support my plugin. Can any of you suggest how I should support the plugin starting from the new Firefox 41 to the future release as well? As per my knowledge, they have a future plan to support the native messaging, but till then how ...!!! Moreover do any of you have any information, by when can we get the native support from Firefox.

  5. Anonymous
    September 11, 2015 at 11:48 am

    Until I can cast Firefox to Chromecast, I will stick to Chrome.
    My wife uses Firefox and all I do is listen to her complain about how slow it is.

  6. Anonymous
    August 27, 2015 at 7:19 am

    Any Browser Without A Huge Extension Library Is Mostly Useless To Me:

    A - I Abandoned IE8 When I Discovered FF - Never Looked Back.

    When A Browser Screws The Compatibility With Their Prior Extensions, I Find Another One To Be My Main Browser, Period:

    B - FF4 Screwed Their Old Extensions And I Moved To CHROME - Never Looked Back,

    C - CHROME Screwed All The Extensions From Outside The CHROME Web Store And I Moved To OPERA15+ - Never Looked Back,

    D - Sooner Or Later OPERA15+ Will Do The Same, And So On, And So On, And So On.

    Fortunately, Since ( B ), All CHROME Clones Share Most Extensions, And There Are Lots Of Clones I Have Not Tried - Yet.


    • HenchMeister
      March 1, 2016 at 10:49 am

      Please don't start all words in a sentence with a capital letter.

      • Anonymous
        March 1, 2016 at 3:24 pm

        Sorry About That.

        It Is The Output Of A CHROME Extension.


  7. Anonymous
    August 26, 2015 at 2:49 pm

    Mozilla is presently home to many bad ideas and these are yet more examples. My browsing habits make a monolithic browser process a lot more appealing than the process-per-tab model. No thank you.

    Second, the API changes for addons are going to kill NoScript, probably the single most valuable browser security tool available. I'd rather have deep control of Javascript execution than whatever third-rate security options other browsers have and Mozilla-derived browsers are the only ones that allow for that control.

    Fortunately, there's an answer: Pale Moon. It's based on Firefox 25, far enough in the past to have skipped Firefox's last major round of misguided UI changes. It already supports signed addons and all the extensions I genuinely care about are presently compatible.

    The world does not need another Webkit clone of Chrome. It doesn't even need a Gecko clone of Chrome. It needs a Mozilla foundation that actually wants to accept stewardship for the last gasp of open web technologies rather than plans to monetize bundleware that no one uses.

  8. Anonymous
    August 26, 2015 at 1:37 pm

    "If you’re not so sure, consider these points: Firefox lets you customize everything."

    This will no longer be the case with WebExtensions extensions. XUL and XPCOM are the only reason Firefox extensions are as powerful as they are. Even the developer of DownThemAll has expressed disgust at Mozilla's plan to deprecate XUL/XPCOM, since Chrome extensions are so much weaker than Firefox's current capabilities.

    The last time I tried using Chrome, it took me two extensions to get a full digital clock (one that didn't have tiny text, with the hour stacked over the minutes): one for the hour (one tiny icon) and another for the minutes (a second tiny icon). Firefox's FoxClocks and SimpleClocks extensions allow me to format the day, month, year, and time as text in a single extension, however I wish (currently 3-letter day-of-week, 3-letter month, day, a bullet, hour:minutes, AM/PM - and I can alter that any way I wish!) Chrome would require me to hover over the tiny icon to display the date in a tooltip.

    • Anonymous
      September 17, 2015 at 6:28 pm

      Switched to Pale Moon (an Open Source web browser forked off from Firefox/Mozilla code with no Australis), they are keeping support for XUL, XPCOM and XBL source code that these wonderful add-ons use to make Firefox flexible in every way.

      Link: [Broken Link Removed]

  9. Anonymous
    August 26, 2015 at 7:51 am

    DownThemAll is the only reason I was still using Firefox. Wanted to move to Chrome, but it has no extensions to boost download speed. The closest thing I've found was the Citiro browser (chromium-based). It has a download accelerator similar to dTa. Why can't Chrome have one?

  10. Anonymous
    August 25, 2015 at 5:49 pm

    "Very soon, you’ll be able to run all your favorite Chrome extensions in Firefox. "
    Will this open up FF to surreptitious snooping by Google?

    Looks like FF is following Opera to becoming a version of Chrome. No matter how I try, I cannot escape Google's tentacles. Like kudzu vine, Google is insinuating itself into every nook and cranny of the online world and taking over the landscape.

    • Anonymous
      August 26, 2015 at 2:57 pm

      Firefox isn't Chrome. Firefox has a different layout engine and a different set of privacy issues and security concerns. The UI is a practical clone at this point; apparently Mozilla long ago gave up the idea of thinking about UIs for itself, but it DOES have its own underlying tools for rendering HTML and processing Javascript. It also currently has a different (I'd argue better) process model and support for NPAPI-style plugins.
      Whatever may happen with Firefox's extensions, it's still not the same thing as Chrome, even if it looks like it and runs the same addons.

    • cd
      May 10, 2017 at 10:22 pm

      I despise Chrome, so for FF to become the same is to drive me far, far away!

  11. Anonymous
    August 25, 2015 at 5:30 pm

    The problem with new firefoxes is: new API is more restrictive, whixh means addons will be limited. Many devs already have said they will be no more new versions because of that. Example: DownThemAll was anounced it will be abandoned. Many other will follow.