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. ilev said on August 4, 2012 at 7:53 pm

    Doesn’t Windows 8 know that www. or http:// are passe ?

    1. Martin Brinkmann said on August 4, 2012 at 7:57 pm

      Well it is a bit difficulty to distinguish between name.com domains and files for instance.

    2. Leonidas Burton said on September 4, 2023 at 4:51 am

      I know a service made by google that is similar to Google bookmarks.

  2. VioletMoon said on August 16, 2023 at 5:26 pm

    @Ashwin–Thankful you delighted my comment; who knows how many “gamers” would have disagreed!

  3. Karl said on August 17, 2023 at 10:36 pm


    The comments section under this very article (3 comments) is identical to the comments section found under the following article:

    Not sure what the issue is, but have seen this issue under some other articles recently but did not report it back then.

  4. Anonymous said on August 25, 2023 at 11:44 am

    Omg a badge!!!
    Some tangible reward lmao.

    It sucks that redditors are going to love the fuck out of it too.

  5. Scroogled said on August 25, 2023 at 10:57 pm

    With the cloud, there is no such thing as unlimited storage or privacy. Stop relying on these tech scums. Purchase your own hardware and develop your own solutions.

    1. lollmaoeven said on August 27, 2023 at 6:24 am

      This is a certified reddit cringe moment. Hilarious how the article’s author tries to dress it up like it’s anything more than a png for doing the reddit corporation’s moderation work for free (or for bribes from companies and political groups)

  6. El Duderino said on August 25, 2023 at 11:14 pm

    Almost al unlmited services have a real limit.

    And this comment is written on the dropbox article from August 25, 2023.

  7. John G. said on August 26, 2023 at 1:29 am

    First comment > @ilev said on August 4, 2012 at 7:53 pm

    For the God’s sake, fix the comments soon please! :[

  8. Kalmly said on August 26, 2023 at 4:42 pm

    Yes. Please. Fix the comments.

  9. Kim Schmidt said on September 3, 2023 at 3:42 pm

    With Google Chrome, it’s only been 1,500 for some time now.

    Anyone who wants to force me in such a way into buying something that I can get elsewhere for free will certainly never see a single dime from my side. I don’t even know how stupid their marketing department is to impose these limits on users instead of offering a valuable product to the paying faction. But they don’t. Even if you pay, you get something that is also available for free elsewhere.

    The algorithm has also become less and less savvy in terms of e.g. English/German translations. It used to be that the bot could sort of sense what you were trying to say and put it into different colloquialisms, which was even fun because it was like, “I know what you’re trying to say here, how about…” Now it’s in parts too stupid to translate the simplest sentences correctly, and the suggestions it makes are at times as moronic as those made by Google Translations.

    If this is a deep-learning AI that learns from users’ translations and the phrases they choose most often – which, by the way, is a valuable, moneys worthwhile contribution of every free user to this project: They invest their time and texts, thereby providing the necessary data for the AI to do the thing as nicely as they brag about it in the first place – alas, the more unprofessional users discovered the translator, the worse the language of this deep-learning bot has become, the greater the aggregate of linguistically illiterate users has become, and the worse the language of this deep-learning bot has become, as it now learns the drivel of every Tom, Dick and Harry out there, which is why I now get their Mickey Mouse language as suggestions: the inane language of people who can barely spell the alphabet, it seems.

    And as a thank you for our time and effort in helping them and their AI learn, they’ve lowered the limit from what was once 5,000 to now 1,500…? A big “fuck off” from here for that! Not a brass farthing from me for this attitude and behaviour, not in a hundred years.

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