Web Browsers and Extensions in 2018

Martin Brinkmann
Jan 22, 2018
Updated • Jan 22, 2018

Mozilla's decision to switch the Firefox web browser's extension system to WebExtensions had far-reaching consequences not only for Firefox but also for browsers that share code with Firefox.

I thought it would be a good idea to take a look at the current state of extension support of popular web browsers.

For this, I took a look at the browser's Chrome, Firefox, Edge, Vivaldi, Opera, Pale Moon, SeaMonkey and Waterfox, and what options users of these browsers have to download and install browser extensions.

Note: Mozilla switched to the new extensions system in late 2017. Browsers based on Firefox code may not have transitioned entirely to the new system or a custom system.

Web Browsers and Extensions in 2018

The table lists the browsers on the y-axis and the extension systems on the x-axis.

Browser/Extensions Chrome Edge Firefox ** Opera Pale Moon
Google Chrome yes no no no no
Microsoft Edge no yes no no no
Mozilla Firefox partially * no yes no no
Opera yes no no yes no
Pale Moon no no no *** no yes
SeaMonkey no no no **** no no
Vivaldi yes no no no no
Waterfox partially * no yes ***** no no
Browser/Extensions SeaMonkey Vivaldi Waterfox
Google Chrome no no no
Microsoft Edge no no no
Mozilla Firefox no no no
Opera no no no
Pale Moon no no no
SeaMonkey no no no
Vivaldi no no no
Waterfox no no yes

* with the help of the Firefox extension Chrome Store Foxified.

** Firefox 57 and newer. Firefox ESR supports legacy add-ons until version 60.

*** Pale Moon supports Firefox legacy add-ons but not Firefox WebExtensions.

**** SeaMonkey supports legacy add-ons only right now. It appears that the developers plan to make the switch to WebExtensions eventually though.

***** Waterfox supports WebExtensions and legacy add-ons currently.

The situation has not changed for Chromium-based browsers or Microsoft Edge. You can separate the extensions landscape loosely into the following groups:

  1. Google Chrome extensions
  2. Microsoft Edge extensions
  3. Firefox legacy add-ons
  4. Firefox WebExtensions
  5. Opera extensions
  6. Pale Moon extensions

Google Chrome

Google Chrome users can install extensions from the official Chrome Web Store. It is a massive store with lots of extensions but also quite a few underlying problems.

Malicious and problematic extensions are regularly discovered in the Store after they have been offered to users.

Microsoft Edge

Microsoft introduced support for browser extensions in Microsoft Edge in the Windows 10 Anniversary Update. The extension count is very low, however, and it is unclear whether Microsoft is still working on support for Chrome and Firefox WebExtensions.

Mozilla Firefox

Firefox supports WebExtensions only (Firefox ESR is the last official version of Firefox that supports legacy add-ons, but the support ends with the release or Firefox ESR 60 in mid-2018).

Firefox users can install browser extensions from Mozilla AMO. This is the main hub for Firefox WebExtensions.

The Firefox add-on Chrome Store Foxified adds a second option however, as it adds support for many Chrome extensions as well. Firefox users may install Chrome extensions from the Chrome Web Store after installing Chrome Store Foxified.


Opera is another special case. Since it is based on Chromium, it does support Google Chrome extensions. Opera Software maintains the Opera add-ons website next to that which is the central Store for extensions for the browser.

Opera users can also download extensions from Google's Chrome Web Store using this extension.

Pale Moon

Pale Moon supports Firefox legacy add-ons and add-ons offered on the Pale Moon Add-ons Site. The makers of the browser announced recently that Pale Moon won't support add-ons from Mozilla AMO directly anymore once Firefox ESR reaches version 60.

Mozilla revealed some time ago that it had plans to remove legacy add-ons from AMO after support for these add-ons ends in all Firefox browsers. Pale Moon users can install these add-on manually after the switch is made.


SeaMonkey switched to Firefox ESR recently to buy more development time. The browser supports legacy add-ons only right now.


The Vivaldi browser supports Chrome extensions. Users can head over to the Chrome Store and install browser extensions from the Store directly.


Watefox supports legacy extensions and WebExtensions currently. Users of the browser can download extensions from Mozilla AMO, and they may also use Chrome Store Foxified to download WebExtensions from the Chrome Web Store.

Now You: How important is extensions support for you?

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Web Browsers and Extensions in 2018
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Web Browsers and Extensions in 2018
The guide looks at popular web browsers and the extension systems that they support. It covers Firefox, Chrome, Edge, Vivaldi, Pale Moon, Waterfox and SeaMonkey.
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  1. Doc said on January 26, 2018 at 1:04 am

    Note that, some time in the near future, Thunderbird (Mozilla’s email client) will switch to WebExtensions only, as well.

  2. dark said on January 24, 2018 at 5:33 am

    >Waterfox supports WebExtensions and legacy add-ons currently.

    Tried to install NoScript (which is a WebExtension if i am correct) on Waterfox 56.0.3, doesn’t install, says i am not using Firefox 57. NoScript Classic works on Waterfox.

    1. John Fenderson said on January 24, 2018 at 5:37 pm

      NoScript Classic is still the better extension anyway.

    2. Appster said on January 24, 2018 at 10:32 am

      That’s because of a version number restriction imposed by the NoScript author.

  3. TelV said on January 22, 2018 at 11:03 pm

    If the user has Waterfox with the Self-Destructing Cookies addon installed which is incompatible with FF56 on which it’s based, multiprocess must be disabled otherwise sites may not load.

    Use Mozilla’s Compatibility Reporter to check which addons are compatible with FF56: https://addons.mozilla.org/addon/add-on-compatibility-reporter/

  4. Rick A. said on January 22, 2018 at 8:13 pm

    Martin, Google Opera does support Google Chrome extensions with Google Opera’s “install Chrome Extensions” extension – https://addons.opera.com/en/extensions/details/download-chrome-extension-9/

    1. Martin Brinkmann said on January 22, 2018 at 8:18 pm

      Rick you are right. I added the info in the table but forgot to add it to the Opera part of the article as well. Added and thanks!

  5. TelV said on January 22, 2018 at 6:50 pm

    The page doesn’t display properly Martin. Ads on the right hand side overlap the last column of the chart whereby the Waterfox column isn’t visible: https://imgur.com/nVTZJWA

    1. Martin Brinkmann said on January 22, 2018 at 7:37 pm

      Thanks, corrected that by separating the table.

  6. MikeK said on January 22, 2018 at 6:45 pm

    Chrome and Firefox are still my go to. My main concern with them is the bookmark managers. I prefer Bookmark OS

  7. John Fenderson said on January 22, 2018 at 5:49 pm

    Extensions are critically important to me, which is one (or both) of the reasons why I decided not to move to Quantum and am happily using Waterfox.

    The “or both” aside is because the second reason why I decided not to move to Quantum was the UI. While the Quantum UI isn’t as horrid as Chrome, it’s pretty close. Before Quantum, I could use an extension to fix Mozilla’s terrible UI decisions — but the neutered WebExtensions make it impossible to do this under the new scheme. So, I’m staying with the old.

  8. Kubrick said on January 22, 2018 at 2:49 pm

    With the existence of several adblockers i consider this a complete and utter waste of time and it seems herr google wishes to dictate what ads are shown and which are not..

    1. Richard Allen said on January 22, 2018 at 5:18 pm

      You’ll like this. (*sarcasm) DNS-based Ad Blockers are broken on latest Chrome versions: “https://www.xda-developers.com/fix-dns-ad-blocker-chrome/”

  9. Richard Allen said on January 22, 2018 at 1:24 pm

    For the most part I’m fine with extension support from the major browsers. Over the last year I was able to seriously reduce the number of add-ons that I use in most of my browsers, Pale Moon has 26 and the rest a lot less. In Firefox I still miss the session manager from Tab Mix Plus and I miss the easy access (toolbar replacement) to the bookmarks toolbar when using the ‘Bookmarks menu’ legacy add-on. Which explains why I sometimes find myself using FF v56 as much as the newer versions. I was hoping that Waterfox would be able to replace my need for a pre-FF v57 browser but the current version of Waterfox isn’t doing it for me.

    1. Appster said on January 22, 2018 at 6:38 pm

      @Richard Allen: What’s wrong with Waterfox? I can see no disadvantage when compared to Firefox 56…

      1. Richard Allen said on January 22, 2018 at 7:51 pm

        I tried it back when and felt it was a little too beta for me. Actually, I thought calling it a beta was a little generous. In comparison, Chrome Dev and Nightly were much more usable. I’ll check it out again in the future.

        As far as I can tell, “Tracking Protection” has never worked in WF v56 and the new Options layout doesn’t work either (browser.preferences.useOldOrganization=false). I would prefer that FF and WF use the same UI. The UI is minor but no tracking protection is a big deal, for me. Tracking Protection is a very easy work around for websites using ad block blockers, it’s easier and faster, without loss of website functionality, than disabling 3rd-party js or figuring out which network request is responsible. When using the built-in Tracking Protection a site can be whitelisted in your content blocker without having to give up protection from tracking and from potentially deceptive, maybe even, malicious ads. Ad block blockers are almost always temporary, so a website can be “temporarily whitelisted” w/uBO and at the next browser restart the whitelisted entry will not be in effect. And rarely does Tracking Protection trigger a website complaint or show any ads, in my experience. One of my goals is to use as few addons as possible. uBlock Origin (globally blocking 3rd-party iframes) and No-Script Suite Lite are the only two security/privacy related addons I use. No-Script Suite Lite is used as a javascript whitelist, new sites are auto blacklisted and ‘most’ sites I regularly visit end up whitelisted but uBO can still be used to disable 3rd-party js or whatever. With FF I have the level of protection I want without sacrificing ease of use and with the least amount of addons used as possible. I’m hoping Waterfox will get tracking protection working so that I can then uninstall FF v56.

    2. Ron said on January 22, 2018 at 6:37 pm

      >>I was hoping that Waterfox would be able to replace my need for a pre-FF v57 browser but the current version of Waterfox isn’t doing it for me.<<

      Have you tried Basilisk?

      1. Appster said on January 22, 2018 at 6:38 pm

        Basilisk is beta software.

      2. John Fenderson said on January 23, 2018 at 10:12 pm

        @Appster: “Basilisk is beta software.”

        I’m not sure what you mean by pointing this out. In this day and age, pretty much all software is beta software. I wouldn’t let that put me off from giving it a try. If something important is broken in it, then you can just stop using it. No harm done.

    3. kalmly said on January 22, 2018 at 4:20 pm

      Tab Mix Plus’ session manager is the main reason I have stayed with FF 56. I never had many add ons installed, but that one, I just don’t want to be without.

  10. jupe said on January 22, 2018 at 11:33 am

    I am happier now with the 10 or so WebExtensions I have in Firefox 59 than what I had in the legacy versions, even after all the doom and gloom spouted everywhere about the changeover.

  11. Anonymous said on January 22, 2018 at 10:25 am

    Martin, Chrome 66 is out now with Chrome’s built in ad blocker, will you do a demo for it ?

    1. Richard Allen said on January 22, 2018 at 1:22 pm

      From what I can see with Chromium v66 on Android (haven’t tried the Windows version), it only works on ‘some’ sites but then I am yet to find a site that it works on. A full page ad for the “bleacherreport.com” android app is still acceptable, I guess because you can scroll down to the article. Fact is a lot of websites show a banner for their android app and unless you have child size fingertips good luck closing the banner and not winding up in the Play Store, LoL. I just don’t see Chrome’s ad blocker ever doing much in the future, especially on popular high-traffic websites. The vast majority of ads are always going to be acceptable. Hopefully I’m wrong but…

      1. John Fenderson said on January 22, 2018 at 6:31 pm

        “The vast majority of ads are always going to be acceptable”

        No ad that comes with tracking can be acceptable.

    2. Martin Brinkmann said on January 22, 2018 at 10:33 am

      Does it work on the desktop? To the best of my knowledge, Google only vetted mobile versions of sites until now.

  12. wybo said on January 22, 2018 at 10:21 am

    It seems they are quite important. Initially I used FF Quantum but I started to miss some of my legacy addons. I also was not enamored with No Script 10.X. So i switched to WaterFox. Not regretting one moment of it. To me speed of loading is not an issue at all. Mind you WF is very quick.
    I read that Alex will start a WF AMO so that all (legacy) extensions will be curated for us. Excellent!.

    1. Sophie said on January 22, 2018 at 1:07 pm

      @wybo – if true, this is EXCELLENT news!! I keep wanting to know, and hear for sure….that WF will curate, hold, store….and make forever available, the old AMO.

      Great news indeed.

      I will still use Quantum (as well). I like it…but I also can’t be without my old Addons, and maintaining them (all 76 so far!)

      I even tried to download the whole AMO with an offline download….but gave up after three days! Haha! They probably throttled me, actually!!! :)

      1. wybo said on January 23, 2018 at 8:28 am


        I read it here under the what’s due in Q1 2018: https://www.waterfoxproject.org/blog/waterfox-56.0-release-download

      2. John Fenderson said on January 22, 2018 at 6:30 pm

        Why not just download the legacy extensions that you use? That’s what I do, so I will always be able to reinstall them as needed, even after they’re purged from AMO.

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