Blocking the Skype Toolbar in Firefox

The Skype Toolbar for Firefox is an extension that detects phone numbers in web pages, and re-renders them as a clickable button that can be used to dial the number using the Skype desktop application. This extension is bundled with the Skype application, and is installed into Firefox by default when Skype is installed or, in some circumstances, updated. As a result, a large number of Firefox users who have installed Skype have also installed the Skype Toolbar, knowingly or unknowingly.

The current shipping version of the Skype Toolbar is one of the top crashers of Mozilla Firefox 3.6.13, and was involved in almost 40,000 crashes of Firefox last week. Additionally, depending on the version of the Skype Toolbar you’re using, the methods it uses to detect and re-render phone numbers can make DOM manipulation up to 300 times slower, which drastically affects the page rendering times of a large percentage of web content served today (plain English: to the user, it appears that Firefox is slow loading web pages). We believe that both of these items constitute a major, user-facing issue, and meet our established criteria for blocklisting an add-on.

As a result, we’ll add all versions, up to and including the current shipping and beta versions, of the Skype Toolbar to the Mozilla Firefox Blocklist for all versions of Firefox. The blocklist entry will be a “soft block”, where the extension is disabled and the user is notified of the block and given the option to re-enable it if they choose. It’s also important to note that the Skype application itself will continue to work as it always has; only the Skype Toolbar within Firefox is being disabled. The blocklist entry will be added sometime in the next 48 hours, and will be in addition to the existing soft block on earlier versions of the Skype Toolbar.

We’re tracking the issues we’re seeing with the Skype Toolbar in bug 615799, and the blocklist process in bug 627278. We’ve recently established contact with the Skype Toolbar team, and will work with them to identify the issues that should be corrected, and will lift the soft block on future versions that address those issues.

113 responses

  1. Mook wrote on :

    So what is the non-slow way to do what they wanted to do? (I’m guessing scrape for phone numbers to add the calling UI, including dynamically added text.) Bug 530995 didn’t seem to offer any solutions.

    Blacklisting things seem fine to me, but only if there has been an attempt to provide fixes…

    1. Boris wrote on :

      There non-slow way to do it is:

      1) Don’t do it on every mutation.
      2) Don’t post an event to trigger it on every mutation.
      3) Don’t use mutation event handlers, ever.

      If they really think they want to scrape for phone numbers after onload, say, one way to do that is to do the scraping when the user hovers over their toolbar or whatever. Because, again, there is no point doing it on every mutation.

      1. smaug wrote on :

        Since it is a binary extension, they could use mutation observer, which is
        significantly faster than mutation events.
        Though, even that could be slow if they don’t batch the mutations.

        1. Mook wrote on :

          Sadly, the more Mozilla-supplied XPCOM/platform things you use, the more likely you’ll cause crashes the next time Firefox has a minor point update.

          Until there’s a useful future-proofing story (and unfreezing everything for Firefox 4 certainly isn’t helping!), the best practice is and always has been keep as much as possible in JS. And that means both source and binary compatibility.

          Sorry, you can’t have both the flexibility of changing internals whenever _and_ have people using it.

      2. Mook wrote on :

        That means for something like GMail, the user will need to manually trigger everything because the load event is completely useless? If you _don’t_ do it (eventually) on every mutation, you might as well not exist – for much the same reason supermarkets put candies and gum next to the checkout.

        Yes, I understand that mutation events are slow because event dispatch is slow when you do it a lot. But I blame that on Gecko _not_ having an appropriate “tell me when things are done changing and give me some set of things that changed” event. Yes, refresh driver, etc. That’ll ship… sometime in 2013 as a beta?

        In the Skype-specific case, adding the extension in their installer without clearly informing the user is, indeed, their bad. But that’s completely separate from Mozilla side not appearing to actually offer solutions in the relevant bug and just going for the banhammer.

        I know Mozilla doesn’t really want to admit this, and has been bad at it and will only get worse (due to planned shorter release cycles), but Firefox is a platform and is only interesting because it is a platform. Sometimes that requires doing work that benefits extensions instead of trying to turn it into Netscape 6.

    2. PHFM wrote on :

      OK I am not trying to be smart,BUT what is the ‘skype toolbar’
      I use skype all the time and 1/2 thru a conversation Mozilla drops out completely.If this is one of the reasons,where do I locate this toolbar.
      Please some one tell me more.


      1. spook wrote on :

        the toolbar could be located in a few ways: (mozilla)

        1. skype icon on the right side with numbers 1,2,3 on it. clicking that would give you the option to uninstall/disable the toolbar

        2. go to tools>add-ons>and go to the “Extensions” tab and look for “skype extension” > then select disable

        3. tools>skype extension>then a popup would show with the options to disable/uninstall it. ..

    3. Amila wrote on :

      Mook, and all… Greetings. Loving the dialogue. But, I am wondering how much it is that Mozilla charges for using the Firefox browser… …. OK…. so I know its FrEE…. …. just checking.

      The only problem that I have with any toolbar or add on being installed is when any such items are installed without my authorization.

      Beyond that, I would much prefer that the folks at Mozilla take the safe road, at least until known issues are definitely resolved.

      Thanks, Mozilla team!

  2. Fred wrote on :

    Full-text page searches are slow anyway. What might have been particularly slow was possibly the way they decided it was time to search again — you can do that on a timer, for example, but only if certain events were fired in the mean time. If you attach to events directly, it is possible you execute full-text searches all that time, etc.

    So while it’s an inherently slow operation, there are more and less efficient ways of handling this problem.

    1. Bill Calfee wrote on :

      OK, so I would like to know how to get rid of the Skype extension. Any help?

      1. bill wrote on :

        When I left click on the Skype logo on the tool bar it shows uninstall. Or remove extension from Firefox.

        Don’t know if this is the answer, but it is there

  3. Wladimir Palant wrote on :

    Thank you! I found that their new version is again doing something that breaks overlays (meaning that Adblock Plus won’t work for some people).

  4. Lino wrote on :

    PLEASE do this for ALL the installed-without-explicit-request toolbars and plugins.

    This shit should be strictly opt-in.

    1. Mario wrote on :

      Are You Telling That Youre Asking To Block Almost Half Of The Millions Of Addons! Cause Half Of The Addons Will Put A without-explicit toolbars! No I don’t agree. If Install Google Talk Will Install Google Toolbar, Must It Be Blocked? If That Happens The Google Toolbar Will Not Be Available At The addons page! Sorry For The spelling mistakes…

      1. Kissaki wrote on :

        Such toolbars are no way half of the millions of addons.
        Maybe you’re thinking about all addons adding icons, buttons etc?

      2. Lain_13 wrote on :

        1. Look at statistic of most popular addons. There are no toolbars. So, “millions” is a lie.
        2. Softblock doesn’t remove extension/plugin completely. It just disables it _BY DEFAULT_.

        So, theoretically FireFox _must_ disable all addons installed from outside without user’s approval and inform user about such events to give ability to enable such addons if it’s necessary and user _know_ about installation of these addons. Additionally Firefox must hardblock tricksters who will try to avoid this behavior and enable addon without user’s approval if it will be possible to do.

        1. Jim wrote on :

          I think a good compromise would be to block at initial installation and then if the user has overridden the block let updates proceed with perhaps a warning. Give the user the ability to disable the warning if they want. That way you opt in once and everyone is happy.

      3. Kangaroo wrote on :

        *All* and *every* change to a person’s computer should be explicitly authorized by the person responsible for the computer. That *does* include installation of libraries, add-ons, add-ins, extensions, you name it. Even if the user does not understand exactly what is to be installed, at least (s)he was offered a chance to know and decide – even if it takes a little research before making a decision.
        What is *not* admissible is that somebody comes to one’s computer and starts making changes without the “informed consent” of the computer owner/user.
        Do you want your privacy to be sistematically violated? Would you like the government to install spyware on your machine? Would you like companies to block your computer the way Microsoft intended with its Genuine program? Do you like when shitty programs put garbage in your machine without you knowing and that garbage brings your machine down?
        And, Mario, please, please, please, don’t start every word with a capital letter. That’s wrong in *every* language I have ever heard of, and it is *very* irritating!

        1. Jacob Tabak wrote on :

          The system as it is now is fine. Remember when Vista came out and the UAC popup was driving people nuts and adversely affecting sales?

          You get one popup that allows a single program (Skype installer) to do whatever it wants with your computer.

          I’m not sure who your rant is directed at (app developers? operating system developers?) but it is naive and idealistic.

          If you want to target a specific problem, like rogue firefox extensions, then let’s talk about that. When a program installs an extension, you are notified of it the next time you open Firefox and are indirectly given the opportunity to disable it at that time.

          Perhaps it would be good to refine this process. Instead of saying “New addons have been installed”, pop up a box that describes the addon, and then has comments/ratings from users about that addon, and present a clear choice to the user about whether or not they want to allow the addon to be enabled.

          1. Dusty wrote on :

            You are the ranter Jacob! And an inconsistent one at that. One minute the ‘system’ is “fine”, a few pars later it’s ‘perhaps’ “good to refine” it. But you entirely miss the point that it comes down to a sound principle, the principle of Property Rights, i.e. if it’s *my* computer every change to it must be made only with my informed consent. So you are so very wrong, “The system as it is now is fine.” NOT! It is actually most UNsound. Go back to devising your beloved rules but live them yourself instead of dumping them on others.

            “The personal right to acquire property, which is a natural right, gives to property, when acquired, a right to protection, as a social right.” — James Madison

            P.S. As to naivety and idealism, you demonstrate those traits yourself above, so stop projecting onto others your own shortcomings, Mr Tabak.

          2. Evert wrote on :

            I would be happy with the last proposition of Jacob.

            But the pop-up should come from Firefox. Why not inform directly about possible problems in the use of the add-on.
            Also there should be any usefull sign or statement that the add-on is free from virusses, tracking cookies, addware, spyware, etc.

        2. Roger Wolff wrote on :

          This is a sliding scale. If I install an ubuntu package on my system, it often installs more than just the binary I asked for. Some required libraries, some configuration files, some documentation etc etc. Sometimes my common sense tells me it’s installing too much. For example, when I install “xnetload” on a remote server it also installs a whole lot of libraries that are required for “run Xwindows on this machine”, but not for displaying on a remote machine as I’m intending.

          Similarly, you can argue that Skype as a package comes with the toolbar feature. You requested the Skype package, and it comes with a firefox toolbar. You can even disable it if you want….

          Anyway… I personally think that automatically adding toolbars to the browser is NOT a valid part of a package. So I agree that Skype overstepped its boundary. But it remains difficult to say where that boundary should be exactly…..

    2. Kissaki wrote on :

      Pretty much all toolbars can be deselected from install of those applications.
      It’s the users just clicking next all the time on the installers.
      Of course that’s what those publishers play with, they hide the checkbox, they pre-select it, and sometimes even hide it in a different install mode (default/standard vs custom where you can change components and path).

      1. kev wrote on :

        “and sometimes even hide it in a different install mode (default/standard vs custom where you can change components and path).”

        Which is exactly what’s being done in this case, and a lot of people are unaware it’s even installed as a result. (you need to click on “Options” in the first window of the installer, and then deselect the toolbar for Firefox)

  5. Kissaki wrote on :

    Nice move!
    Nobody needs that crap.
    Sad so many ppl. happily install it without knowing and without realizing or removing it later on.
    This blacklisting is a good move though.

  6. Val wrote on :

    Thanks FireFox team! I never install toolbars if I see the option. I’m glad I can keep my favorite things Skype and FireFox. Nice to know someone’s got my back =]

  7. Serge wrote on :

    Can you please add in the Firefox a feature – asking the user to approve of just registered plug-ins?

    In more details:
    Each start the Firefox looks for plug-ins and starts to use them. Instead of silent use of just appeared plug-ins it can show a list of “just found new plug-ins” and with choices “use”, “disable/never use it”, “un-install/move to black list of plug-ins”.

    I really don’t like that other “good” tools tries to hijack my nice browser for whatever reasons without any notice to me.

    1. Justin Scott (fligtar) wrote on :

      Yes. We had hoped to do this for Firefox 4, but weren’t able to finish it in time, so look for it a little later this year. Some relevant bugs to follow for this are: and

      1. Sebastian Muniz wrote on :

        This usually adds issues with users. Let’s state the obvious:
        Most users don’t know what an extension is or how to deal with it.
        A lot of vendors installs plugins on firefox to support their business.

        Confronting an user with a dialog like: Do you really want to enable java console 6.0.17? might cause panic.

        However I do think that the browser needs an authentication method to avoid execution of any non authorized plugins by default.

        1. Eric Poncho wrote on :

          “Most users don’t know what an extension is or how to deal with it.”


          “Do you really want to enable java console 6.0.17? might cause panic.”

          It might, but not saying anything will keep the user in the dark, thereby ruining any chance of him/her ever knowing what an extension is or how to deal with it. So the challenge is educating the user. Jacob Tabak’s earlier comment is, I think, the way to go:

          “Instead of saying “New addons have been installed”, pop up a box that describes the addon, and then has comments/ratings from users about that addon, and present a clear choice to the user about whether or not they want to allow the addon to be enabled.”

          As others have said here, the user has to be in control. Unless it is totally justified (like say, when an add-on cripples the whole browser), we have to decide what we want to install or not and can’t let someone else, be it microsoft, apple or mozilla, decide for us.
          If not, the next logical step is hardware locking when running a program that hasn’t been licen$ed by the hardware manufacturer *shivers*

  8. Mihailo wrote on :

    Thanks! That’s the first thing I do when I install Skype – disable the bloody toolbar.

    1. warder wrote on :

      Download the Business Version of Skype… the MSI file. There is no toolbar 🙂

  9. Max wrote on :

    What have I to do to uninstall this addon? Uninstall options is deactivated…

  10. Jordi wrote on :

    Really really well,…

    We had problems with our web applications with ppl have skype addon. It’s a really good new.

  11. Maiqui wrote on :

    A scandal that during the installation, Skype don’t if we agree or not to install this bar. I have removed this rubbish Skype bar from the programs and therefore from Firefox.

  12. Harriet wrote on :

    How to I disable this toolbar?

  13. hongbo wrote on :

    nice, I don’t really like skype because of its spyware-characteristic!

  14. Cosmoskitten wrote on :

    Ah, I wondered why I had started to get those weird phone numbers from.

    Well done Firefox team!

    I normally opt out of every toolbar I can, but this one must have slipped by me.

  15. Wschloss wrote on :

    Lino is absolutely right! And Mario probably works for some horseshot add-on spammer.

  16. Jeff wrote on :

    Thanks for the “plain english” version of the description of the issue. I have no idea what an add-on or extention is is in the first place! I really depend on you folks for a worry free internet experience. Thank you for “having my back” and caring enough to work with Skype to fix the issue. You make me proud of the Mozilla team and I see you all as Heros! Please continue to let me know “what’s up” with the Skype service and how it interfaces with Firefox. I wish you the best and thank you again for your assistance to those with no computer literacy. Peace.

  17. Corinne wrote on :

    So how can I uninstall it? The soft-blocked toolbar doesn’t allow itself do be removed when looked up in tools-options-general-manage add-ons. There is simply no option to click that will remove it!

  18. Art McCray wrote on :

    Echoing Val: “Thank you.” Strongly echoing Lino: “PLEASE do this for ALL the installed-without-explicit-request toolbars and plugins.”
    If Google is installing toolbars, or whatever, without an explicit opt-in, that is evil–like Micro$hit. Such a practice, by Google, Skype, or any other organization, is a flagrant expression of contempt for users.

  19. Alex wrote on :

    Contradictionary to some of the comments before: I love the Skype extension.

    We are using a HTML pages based CRM and the Skype extension offers the possibility to click on a number and have it dialled in Skype without any copy/paste etc. This saves time, money and a CTI connection. It is a quick and easy to use solution.

    It is easy to deactivate and thus speed up the page load.

    As far as I know, there is no alternative to the original toolbar or do you know any?



    1. reņģis wrote on :

      you’re the rare exception, because most users just have the Skype extension forced on them and don’t use or need it, and the alternative would be for the CRM system to support Skype links for phone numbers natively by using the skype:?callto handler

  20. Adam wrote on :

    Skype refused to reimburse my cab fare after I interviewed with them. I’m not at all surprised by their level of incompetence.

  21. retimer wrote on :

    Delete Windows and install Linux. There are no problems with Skype in Ubuntu. And no toolbars are added.

  22. bill wrote on :

    PLEASE do this for ALL the installed-without-explicit-request toolbars and plugins. I normally opt out of every toolbar I can.

  23. Stivan wrote on :


  24. J. Geil wrote on :

    For what it’s worth, the Skype toolbar will also clobber textareas that contain Javascript-generated input (e.g., MediaWiki or WordPress) with supposedly toolbar-internal markup. Wikipedia has to filter for broken markup just in case. I’d suggest hard-blocking, honestly.

  25. Christian wrote on :

    I believe I somehow was able to uninstall the toolbar (right-click?) AND keep the extension… no crashes, no delays, as far as I can see.

  26. Don Sullivan wrote on :

    I spent 2 hours a couple of days ago trying to figure out how to send email to skype and have not found out yet. I have had skype about 3 months and have tried to use it 1 time. I have a credit balance and no way to get in touch with them. I would like to cancel it and have my balance returned to pay pal. Any one have an email address for skype, please help.
    Don Sullivan

  27. Marc Thibault wrote on :

    The intelligent way to provide that kind of function is to add it to the right-click menu. The way they’ve done it would be dumb even if it didn’t bring Firefox to a halt.

  28. Ken Jackson wrote on :

    I have two computers, a PC and a laptop, one running Windows 7 Pro and the laptop running Windows 7 Home. Both have SKYPE installed and the program is used daily. I consider myself fairly computer literate yet the exchanges above referencing “Mutation, mutation observer and even binary extension are not terms I use everyday just trying to load and use my email using Firefox.

    Therefore I depend on actions such as Firefox describes and then attempts to intervene which I sincerely hope has nothing but the best interest of the Firefox user in mind. Is it not easy to see why and how so many people on line hold the same feelings deliberately or not.

    I noticed this announcement from Firefox when logging on to my PC, which is my main computer, however no such notice has appeared on my laptop, which is only a few months old, and I have used SKYPE on my laptop several times today.

    I will finish here and go immediately and check my laptop and if any SKYPE addition’s can be found I will know I did not request new add on’s nor give permission for add on’s. They will be deleted right down to the exact registry entry.

    Thank you Mozilla for a great product that I enjoy daily.

  29. joe wrote on :

    Like others, I cannot uninstall! It seems I have to go through a rather fiddlesome process to remove- and I didn’t even choose to install the blighter in the first place..

    1. Claire West wrote on :

      TO UNINSTALL: If it doesn’t work in the Tools/Add-Ons box, just go the Start/Control Panel/Uninstall Programs. There should be two listings, one for Skype and one for the Skype Toolbar. Uninstall the Toolbar only.

  30. mhenriday wrote on :

    Good move – thanks !…


  31. conundrum wrote on :

    Also causes Windows Explorer to crash during file transfers while web browsing it seems, as this problem went away after removing Skype toolbar.

    so far I have wasted hours troubleshooting this POS windows 7 laptop, I am seriously considering taking legal action against Skype for my wasted time

  32. Imran Sarwar wrote on :

    Good do block flash player too, it sucks & crashes my firefox

  33. Chief wrote on :

    And it is not necessary there toolbar from Skype.

  34. MG wrote on :

    Have uninstalled the add-on from the toolbar (I think?!) but computer is still running terribly slow! Anybody know why or what I need to do? Thanks

  35. Techie Salsan wrote on :

    Good to know since I literally just downloaded Skype 20 minutes ago. Thanks!

  36. neokuji wrote on :

    Always choose custom install, and at least review the options/opt-ins/outs prior to any installation!

    We have noticed the drag/delay, and crashes, but thankfully, the issues with Skype have not caused issues/problems with the operation of other extensions (ABP, NS, RP, TB, & RIL being most important!) Yesterday, we were notified via popup message that there were issues with the Skype extension, and were given the option to disable or uninstall the extension… …for the time being we chose to uninstall (successful) the Skype extension until the issues have been resolved.

    We agree with Jeff:…
    “Thank you for caring enough to work with Skype to fix the issue. Please continue to let us know “what’s up” (…the progress made) with the Skype extension.”

  37. Dave wrote on :

    People, people, people ….. it’s only a tool bar. Skype is naturally proud of it and want you to use it, undoubtedly as part of their grand marketing scheme. Slowing down a major league web browser, though, is bad form. I think banning the thing was the correct move. As I said … it’s only a tool bar, not the Holy Grail.

    Good on yer, Mozilla!

  38. Globinch wrote on :

    It was a useful toolbar , but unfortunately could not make it it into a qualified add-on. But since Firefox is one of the most popular browser millions of people are using it across the globe, these performance issues cannot be ignored..

  39. tito wrote on :

    I’ve lots of friends ( no idea about computer ), that when I look into Firefox they have 2 to 4 unwanted toolbars.
    I uninstall these shitty, but these self manage to install again.
    Some of they started to move to chrome mainly because of “unwanted staff sitting on browser” {2cents}

  40. Phillip Gelman wrote on :

    In plain English – how do I block the Skype tool bar?

  41. Mickey wrote on :

    No the reason they are getting rid of it has nothing to do with bugs, it has to do with hax. Come on you can use it to rip phone numbers off websites, so there is a small possibility that say you know someone’s facebook and it’s private that you can still view their information without viewing their page. Of course we all have something like 12 hours before the skype toolbar no longer exists. So lets start hunting! As well besides Skype there are other programs that are becoming incompatible with Firefox like the Bing Bar. Apparently there’s a security risk using it, but I think its more of a risk for the company than the users because they’re still advertising it for IE.

  42. Arsen Ate wrote on :

    Every extension that is installed by default by another application, without user input, should be blocked as a matter of principle. I hate that shady stuff.

  43. Mike wrote on :

    Interesting. What a black eye for Skype. At least *someone* is doing something about the problem. Keep up the good work.

  44. Plain Speaker wrote on :

    Sadly, this is just another example of the risks in using Skype, which is based on an unpublished proprietary peer to peer protocol. In my opinion Skype is a prime example of the triumph of marketing over reality.
    If your live in a country where you don’t already get free international dialling try using SIP based services, they are free between users, safer and cause a lot less problems.
    On the other hand keep using Skype and keep those of us that regularly clean up the mess busy!

  45. Craig McPheat wrote on :

    Wasn’t FF doing this as default for a while?

  46. jacinta hills wrote on :

    my son has just gone to India and set up Skype with web cam for me to communicate with him so I dont want to delete it ,but it appears to affect my internet connection,I have kaspersky protection, is there anything I can do to get rid of the virus without removing Skype?

  47. fakhar wrote on :

    my brother install that extension and i want to disinstall that but i cant disinstall.
    enyone can explane me how to disinstall that extension without disinstall firefox end reinstall?

  48. Kohei Yoshino wrote on :

    A Japanese translation of this article is available at

  49. Melissa wrote on :

    Is there any way to make this list more obvious to users? I’d been experiencing crashes over the past few days, and I thought it was a conflict with the new version of windows live I installed. I did check the firefox website, but making this list more visible would have saved me a big headache.

  50. SkipTML wrote on :

    Here’s a comment on Skype’s side.

    First, if you do not, and don’t want to, call many numbers that show up on web pages using your computer as a VOIP phone, then definitely disable the Skype toolbar in your browsers. And when you reinstall Skype, do the custom install thing and deselect the toolbar from the three browser choices.

    Second, they have changed their installation dialog over time, and I can’t recall if the toolbars are defaulted or not, but I do know you don’t have to use them.

    That said, here’s my take for the toolbar and Skype.

    I use as a contact manager in my job. I’m always tracking people’s phone and email information, and do a lot of outbound phone calling. Domestic US and international. The Skype toolbar and their installation processes have improved from shaky beta to pretty good now over the past year or two. It now works well for me in IE8, Firefox, and Google Chrome.

    I can just click the number in the web page and Skype activates and calls them. Costs much less than the phone company. Fewer misdials, better productivity. I rarely notice the page display time slowing down. (I am intrigued, so maybe I’ll run some tests with it running and not.)

    I heartily recommend that Skype users get an inbound-outbound Skype-Out phone number (there’s a reasonably priced subscription fee for the number and for different calls) and use the extension if you do a lot of phone calling and you have numbers available in web pages.

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