Yet another round of extension recommendations

Update: 15:07 – Added Tab Mix Plus and TBE to the “not install” list.

ComputerWorld managed to generate quite a lot of buzz with its list of must-have extensions and extensions to avoid. But, as many commenters noticed, the extensions listed appear pretty random. The first list contains a number of extensions that are based on good ideas but either didn’t manage to implement these ideas properly or are simply useless to most Firefox users. On the other hand, some extensions that these users would really consider absolute “must-have” like Adblock Plus are simply missing which undermines the credibility of this article. The second article is no better. It lists several very popular extensions without giving good reasons why these should be avoided. And it is filled up with extensions that fall into the category “useless” — as if there were a point in warning users about hundreds of existing useless extensions. No wonder I have yet to see a single positive feedback on this article.

But since extension lists are so popular, I want to present here a list of my own. I do not expect anybody to agree with my choice of extensions, quite the opposite. That’s why I will describe each of them and tell who the extension is meant for, how good it is at doing its job and what its shortcomings are. Being an extension developer myself I choose extensions very carefully and evaluate them not only on the aspect of what they are doing but also on how they are doing it, something that most people don’t notice.


These are the extensions that I have been using for a long time and found very useful (in alphabetical order).

  • Adblock Plus — surfing the web with all the ads is just too painful. The big advantage of Adblock Plus is that it doesn’t touch HTML code of the web pages and only blocks actual requests so that it is far less likely to break web sites than most other ad blockers. The extension attempts to appeal to users with very different skills. Newbies will simply select a subscription and forget about ads. Slightly more advanced users learn to use the context menu to block annoyances. Really advanced users use the list of blockable items and create good filters even for less obvious cases. And unfortunately it takes a really advanced user way too often because the ways in which ads are inserted into web pages get more and more complicated. The other problem of Adblock Plus is its user interface which could be more intuitive.
  • ChatZilla — if you use IRC regularly you will want to install it. The user interface is very intuitive and comfortable while still having every feature you can ask for. Unfortunately, it started showing signs of bloat like overly complicated preferences dialog and nested context menus. ChatZilla could use some focus instead of trying to please everybody.
  • Correct Identity — Thunderbird extension for people who dump all their mail into one account but still want to reply from the address that the mail was sent to. Thanks to that extension I could consolidate half a dozen mail addresses I use while still being able to sort the incoming mail — a great feature, especially given that this extension always works in background, completely unseen.
  • Leak Monitor — an absolute “must-have” for extension developers. This will alert you any leaks of JavaScript objects and show the object that leaked. On the negative side, the leak alert being a pop-up window is quite annoying. This was a huge issue with Firefox 1.5 where it regularly detected memory leaks. Fortunately, by now this extension already made sure that Firefox and most popular extensions no longer show this kind of leaks and leak alerts are very rare.
  • Live HTTP Headers — shows HTTP headers for all requests sent out by the browser and responses received from the servers. It adds a tab to the Page Info dialog, the actual Live HTTP Headers dialog shows you far more information however and even allows “replaying” certain requests with some changes. Very useful tool for web developers and web security testers, especially since it intercepts SSL connections as well. Yours truly made sure that the most obvious shortcomings were fixed, no objections left other than some minor bugs.
  • View Cookies — adds a tab to the Page Info dialog showing the cookies set for the particular page. This is especially useful for web developers and privacy fanatics. Very focused extension, it does only this one thing and it does it very good.

Reluctant recommendations

I am using a few more extensions that are useful but have considerable shortcomings.

  • Adblock Plus: Element Hiding Helper — makes it easier to hide (not block) parts of web pages with Adblock Plus. Unlike Adblock Plus itself, this extension is primarily targeted at advanced users. The most critical issue is that you can easily create a rule that will hide far more than what you selected. This means that to use this extension properly you have to understand how it works which requires at least some basic HTML knowledge and ideally also CSS. But once you got over that hurdle it can be very useful.
  • Dictionary Switcher — good for people who write texts in more than one language. While the spell checker is the killer feature in Firefox 2.0, it works based on the assumption that you mostly use one language. Dictionary Switcher is a big help here, and I exchanged a few mails with its author to improve it. Unfortunately, it still sometimes fails to switch the language correctly. Also, it often switches dictionaries unnecessarily. German dictionary is huge and takes a while to load which makes those unnecessary switches pretty annoying. Ideally the spell checker should be made to keep the dictionary in memory once it was loaded regardless of dictionary switching, I am not sure whether this can be done from an extension however. Still, Dictionary Switcher is certainly better than nothing.
  • Stylish — lets you create and organize user stylesheets that will be applied to web pages allowing to change their look. Clearly targets advanced users even though there is a collection of pre-made styles. But the main problem is its rather awkward user interface, something that shouldn’t be hard to improve — and then Stylish would become a top-notch extension. Myself, I never add any permanent styles to Stylish since all the changes I need can be done with Adblock Plus already. It is useful to test things out however, like how Adblock Plus would look with a different icon.

Extensions I would never install

There are a few popular extensions that are often recommend and that I often install in my test profile for that reason. I would never use them in my work profile however.

  • Adblock Filterset.G Updater — still often recommended “to update filters for Adblock Plus automatically”. Too many people don’t know that Adblock Plus is perfectly capable of updating filters itself and have to deal with the issues of Filterset.G.
  • Fasterfox — is supposed to make your browser faster. My tests indicate in fact that this extension is not a placebo as I originally assumed, and that you get a ca. 20% improvement in page loading times. The price is high however. For a marginal performance improvement you significantly increase the load on the web sites you are visiting. By default Fasterfox will increase allowed number of simultaneous connections from 2 to 8. I know at least two servers that started banning users with too many simultaneous connections because of server load issues, and users who complained usually had Fasterfox installed. Also, Fasterfox enables HTTP Pipelining which is known to have issues with some web servers — yet my tests indicate that pipelining doesn’t have any notable effect on performance. Altogether, most hidden preferences that Fasterfox allows you to change are hidden for a good reason.
  • IE Tab — the idea that you cannot use Firefox as your only browser and that there are many incompatible sites is very persistent. Maybe this is even true for some countries, but ever since Windows can be updated without going to Windows Update page I haven’t seen a single site that would not work with Firefox. If a site looks broken then maybe it is broken — tell the webmaster and come again in a week. Switching to IE for a site that looks broken is not just bad for web standards, it is also dangerous given all the known security holes in Internet Explorer. I use Internet Explorer for testing of course but I only point it to web pages where I know what they do. Finally, some time ago it was possible for a web page to force IE Tab to switch into IE mode. I analyzed the current version of IE Tab and could not find any similar vulnerability, but I cannot be sure that I didn’t miss anything.
  • NoScript — advertised as a security solution. As I discussed earlier this extension doesn’t really make you any safer. People occasionally bring up the argument that they use NoScript and didn’t have a single malware infestation — but they should thank Mozilla developers, NoScript had nothing to do with it. People who simply kept their Firefox browser updated, even those who know almost nothing about computers and simply accepted the automatic updates, have made exactly the same experience. But since NoScript has a blacklist mode as well, it can be used as an annoyance blocker, and some people use it as such. Still nothing for me however, Adblock Plus blocks most annoyances already and the rest of them isn’t worse that NoScript’s attention-grabbing messages.
  • Tab Mix Plus and Tabbrowser Extensions — are supposed to give you more flexibility with tabs in Firefox. This means first of all a preferences dialog that has far more options than Firefox itself. There are people who like this kind of bloat. However, the worst thing about it is the way how Tab Mix Plus and Tabbrowser Extensions are implemented. They rewrite browser functionality freely in ways that make the phrase “huge hack” an understatement. Result are obscure bugs that are difficult to trace back to the extension and are interpreted as Firefox bugs way too often. As a matter of fact, I add this to the list because I just looked into an issue some user reported: links opening pop-up windows (useful ones) didn’t work, the pop-ups were closed immediately without an obvious reason. At least, they were closed most of the time, one out of 5-7 pop-ups stayed.

I hope my perspective will be useful for some people. It is a short list, unfortunately good ideas only rarely meet good programming and user interface design skills so that I have to be very selective with what I install.


  • LorenzoC

    Even if I had to disable it because It was slowing down FF each time I opened a new tab…
    I would also reccommend Firebug.
    It is not for the average user but It is a must for people who work on Web pages and need an advanced debugging tool.

    Wladimir Palant

    I had my trouble with Firebug. It is potentially a nice tool – yet lacking in implementation. I had to uninstall it.

  • insignificant

    I hadn’t realized how Adblock Plus worked. Now I’m wondering if it would provide better page-loading performance than I now get with Ad Muncher. (And there’s also the system-wide performance issue regarding Ad Muncher’s use of global hooks.)

    I have 37 extensions installed, a few of which I think are very good. I won’t bore anyone with any more detail than that!

  • LorenzoC

    By the way, ADBlockPlus is not missing.
    It comes right after NoScript in the list of “extensions to avoid”.
    Adblock and Adblock Plus
    Obviously, we have some bias when it comes to ad-blocking extensions, as Computerworld is an ad-supported site. We also understand that these are very popular extensions. But if everyone blocked ads, how would sites such as ours continue to offer content free of charge?

    Wladimir Palant

    I know that. I was talking about the first list – it is missing there. As to the second, it is one of the extensions where they provided a lame reason for why it should be avoided.

  • Sam

    I find IE Tab very useful for Web Development. And while rare, I still come across the odd site where it is faster and easier to switch the tab to IE, do whatever I wanted to do, then switch it back afterwards. A few days ago Picasaweb wasn’t loading photos in Fx – it was fixed the next day, but while it was broken I just switched the tab to IE to use the site.

    The extensions lists weren’t too bad…I have 8 of the ‘best’ ones installed (out of my 40-odd extensions) and only ABP out of the ‘worst’ lot. I agree about FiltersetG, Fasterfox and Noscript though, they’re all awful.

  • pirlouy

    I agree for all unrecommended extensions.
    However, I have to disagree for an extension: Chatzilla.
    Firefox is already known to be “heavy”. It’s a web browser. Adding IRC possibility has nothing to do with Firefox.

    If you want to use IRC, you’d better use an IM software like Miranda IM (for example). I had been using Chatzilla, but I understood the problem when I had to restart firefox (Java site for example ;-) ). I think you like Chatzilla because IIRC it was kinda pretty, but this extension can’t be in the recommanded list.

    The extension Userchrome.js could be in recommanded extensions too. In fact, it should be built in Firefox. This extension allows to customize browser easily. However, Javascript can be very evil, and can be poorly used, like for an extension…

    Else, I also think LocationBar² and Download Statusbar indirectly allow a better navigation.

    Wladimir Palant

    As I said – I expect you to disagree. But last time when I tried Miranda I couldn’t stand the user interface. And I generally didn’t see any standalone IRC clients with a good user interface. I also don’t understand what you mean by “heavy”. ChatZilla doesn’t add any complexity to the browser (one additional menu item). It doesn’t have any impact on performance or memory use unless you start it – that’s what I expect. It doesn’t seem to cause any significant changes in performance when it is running though is uses up some memory for the backlog – also exactly what is expected. Restarting Firefox is a problem however, which is why I might go for a standalone ChatZilla running on XULRunner in future (no sooner than Firefox will run on XULRunner of course, otherwise it would be a waste of memory).

    I only listed extensions that I have been using for a while so that I can tell for sure whether they are worth using. I never used Userchrome.js however, and neither did I use LocationBar² or Download Statusbar.

  • ABP Fan

    I like Noscript though. I definitely agree that it is an excellent annoyance blocker, In fact I use it as such.
    Noscript is my first line of “defence”, I have configured it to allow all top level domains while blocking scripts from all 3rd party sites.
    This first line takes care of surprisingly many ads that are outside my whitelist.

    Then I have ABP for the finer surgery, it easily takes care of the rest, especially with the aid of Element Hiding Helper and the various subscriptions.

    Then I also use CookieSafe/View Cookies CS to block all cookies by default, and manage the 20-30 cookies from sites I view regularly.

    Blacklisting by default in Noscript is annoying as heck since it breaks sites for me far too often and then I have to allow the scripts anyway plus reloading the sites. This is rarely the case with cookies though, so I find the approach of blacklisting by default acceptable in case of cookies.

    Those 3 are like my trinity of web privacy :3

    (And of course ABP is the most important of my extensions. ABP is 60% of my reasons to use Firefox if that tells you something)

  • rick752

    Besides the more complex extensions, some the “less powerful” extensions provide great use. I love Download Statusbar because I simply hate Fx’s Download Manager or a floating status window that disappears when I go back to Firefox. Having a small progress bar on the status bar is really nice.

    Permit Cookies is a small but really useful extension. I just set my Firefox to ‘session’ all cookies as default and then use permit cookies to always allow or totally block a cookie. The control/status icon sits in the status bar and changes color to show the ‘allow’ status for each site you are on … nice.

    Firebug is also a terrific extension. It was a little buggy at first, but I think that the last update really helped with that.

    Wladimir Palant

    Rick, the last three Firebug updates only helped with security issues. And I am afraid that there might be more, Joe Hewitt really should change the way he displays data.

  • LorenzoC

    I’ve tried NoScript intensively and I’ve got mixed ideas about it. The main flaw in my opinion is the “trusted/untrusted” mechanism. White/Black lists are proven to be un-effective and annoying, maybe un-effective because annoying :). Once you have allowed a site to execute scripts you can’t really know what will happen one day. And “untrusted” is the whole WWW out of your “trusted” list, so you are always asked to authorize something until the white list grows out of control. Does it make sense? You need a “detection by behaviour” or some euristics to run the scripts in a “sand box” and then let them execute or not if they comply the “rules”. IMHO.

  • insignificant

    Mr. Palant: You don’t use Firekeeper? I learned about this extension from you… But you only did say you prefer its approach over that of NoScript, and not that you actually use it.

    Wladimir Palant

    No, Firekeeper is in early alpha stages and I don’t think it is good for anything other than testing the concept. I might try it later when it matures.

  • Greg

    I use extensions for three main reasons – safety, convenience and UI improvements.

    For safety:
    Adblock Plus *
    Adblock Plus: Element Hider Help
    CookieSafe *
    Flashblock *

    For web convenience:
    Gmail Manager
    IE Tab
    Show Image
    Stop Autoplay

    For UI improvements:
    Add to Search Bar
    Context Search *
    Organize Search Engines
    Download Statusbar
    Tab Mix Plus
    Tiny Menu

    The ones with asterisks are recommended for anyone. The others are all useful, but may not be for everyone.

  • insignificant

    I use a lot of the same extensions Greg does. But I recently did away with the Context Search extension after (finally) realizing I could simply drag one or more words to the search bar to effect the same thing. When you drag to the search bar and use the Second Search extension, it pops up the search menu nicely. If the Context Search extension had a menu icon, it would be easier for me to pick out among all the other context menu items, and I might use it again. Oh well, who cares, right?

    Oh—regarding Firekeeper: I think it’s useful, if (a big “if”, I know) it works without introducing other problems. And so far, to me it seems to do just that. I recently began using the Malware Block List with Firekeeper. Nice idea that seems to work pretty well. But the default Firekeeper list seems pretty lacking so far.

  • Bill

    The IE tab is a wonder for those of us in specialty fields (mine is Real Estate). Getting the powers-to-be to program for Firefox is remote. We are perceived as being a small group of nerds.

  • Brett

    Just as Adblock Plus gets used without noticing i recommend “Drag de Go”, u can alter the default settings to let u open links in the background just be clicking and dragging a link, instead of right clicking and going to open in new window. It also lets u select text and drag the selected text to open up a search window in the background with ur default search engine.

  • Matt Nordhoff (Peng)

    There are caveats with some of those:

    ChatZilla — If you’re someone like me who’s in like 30 channels 24 hours a day, it will use a LOT of memory. Using XULRunner (as of sometime last year), like 200 MB after a few weeks or a month. And then it’ll probably crash. While I’m sure it’s Gecko’s fault (and the obvious and useful choices CZ made since it’s based on Gecko, like using HTML for channel views), that doesn’t make it any more usable on a system without a lot of extra RAM.

    Live HTTP Headers — Something to be aware of is that it isn’t always exact. Capitalization of header names can vary (I send “ETag” headers and it shows “Etag”) and if you send more than one of some headers, it will be collapsed into one. Also, the Page Info header tab will list headers in <meta http-equiv> tags at the end (but their names will be all-lowercase). I use when I need to see exactly what is sent.

    (Lists don’t work in comments? That sucks.)
    (Nor does surrounding code in @s?)
    (HTML is also stripped instead of escaped in the Message box after hitting the preview button. Hopefully it won’t be stripped when I submit this.)

    Wladimir Palant

    LiveHTTPHeaders only displays the headers as Gecko has them. They might be normalized already (though this is rarely the case). And – of course a sniffer can get more information, theoretically. But using a sniffer is very rarely necessary if you have LiveHTTPHeaders. And you cannot replay a request with a sniffer (note that this feature also has its limitations but it is very useful nevertheless).

  • Jakob Breivik Grimstveit

    Nice to see your view on IE Tab and Fasterfox, amongst other things. Good thing to be reminded about Live Headers, will have to install that one again, even though I’m not a web developer anymore :-)

    Keep up the good work, both in regards to the blog and the extension development!

  • Don Pedro

    “I haven’t seen a single site that would not work with Firefox. ‘’ you wrote about IE Tab.

    Maybe you do not spent a lot of time surfing on internet !

    Unfortunately or not IE Tab is a must have .

    You miss lines or information on some sites.
    the owner login…if you do not install IE Tab the line about the VAT does not appear and you can’t fill the form.
    I asked them to correct it 2 years ago still the same.,problem etc…

    Even I could not complete this order without to install IE tab. (It was 2 years ago I did not check this year), I can’t send you money from this bank if IE Tab is not activated.
    Friendly regards