The Road to Firefox 57 – Compatibility Milestones

Update: this post was updated to reflect a change in how we determine when Firefox will run in multiprocess mode. Firefox won’t run in multiprocess mode unless add-ons are explicitly declared to be compatible with Multiprocess Firefox. Compatibility shims will be removed earlier than indicated in the previous version of this post.

Update 2: we can now confirm that this plan also applies to Firefox for Android.

Back in November, we laid out our plans for add-ons in 2017. Notably, we defined Firefox 57 as the first release where only WebExtensions will be supported. In parallel, the deployment of Multiprocess Firefox (also known as e10s) continues, with many users already benefiting from the performance and stability gains. There is a lot going on and we want you to know what to expect, so here is an update on the upcoming compatibility milestones.

We’ve been working on setting out a simple path forward, minimizing the compatibility hurdles along the way, so you can focus on migrating your add-ons to WebExtensions.

Legacy add-ons

By legacy add-ons, we’re referring to:

Language packs, dictionaries, OpenSearch providers, lightweight themes, and add-ons that only support Thunderbird or SeaMonkey aren’t considered legacy.

Firefox 53, April 18th release

  • Firefox will run in multiprocess mode by default for all users, with some exceptions. If your add-on has the multiprocessCompatible flag set to false, Firefox will run in single process mode if the add-on is enabled.
  • Add-ons that are reported and confirmed as incompatible with Multiprocess Firefox (and don’t have the flag set to false) will be marked as incompatible and disabled in Firefox.
  • Unless your add-on has the multiprocessCompatible flag set to true or is a WebExtension, Firefox will run in single process mode. Firefox will run in multiprocess mode if all enabled add-ons meet this criteria.
  • Add-ons will only be able to load binaries using the Native Messaging API.
  • No new legacy add-ons will be accepted on (AMO). Updates to existing legacy add-ons will still be accepted.

Firefox 54-56

  • Legacy add-ons that work with Multiprocess Firefox in 53 may still run into compatibility issues due to followup work:
    • Multiple content processes is being launched in Firefox 55. This enables multiple content processes, instead of the single content process currently used.
    • Sandboxing will be launched in Firefox 54. Additional security restrictions will prevent certain forms of file access from content processes.
  • Multiprocess compatibility shims are removed from Firefox, starting with the Nightly and Developer Edition channels.

Firefox 57, November 14th release

  • Firefox will only run WebExtensions.
  • AMO will continue to support listing and updating legacy add-ons after the release of 57 in order to have an easier transition. The exact cut-off time for this support hasn’t been determined yet.
  • Multiprocess compatibility shims are removed from Firefox. This doesn’t affect WebExtensions, but it’s one of the reasons went with this timeline.

For all milestones, keep in mind that Firefox is released using a “train” model, where Beta, Developer Edition, and Nightly correspond to the future 3 releases. You should expect users of pre-release versions to be impacted by these changes earlier than their final release dates. The Release Calendar lists future release dates per channel.

We are committed to this timeline, and will work hard to make it happen. We urge all developers to look into WebExtensions and port their add-ons as soon as possible. If you think your add-on can’t be ported due to missing APIs, here’s how you can let us know.

144 responses

  1. Kees wrote on :

    I’m a bit puzzled about what Mozilla is trying to do. First there is much work on getting the classic add-ons running with multi-process Firefox and when this is more or less stable then suddenly WebExtensions are announced. WebExtenstions is fine, however de-supporting the classic add-ons less then 2 years after WebExtensions is announce is wrong. In my opinion the classic add-ons should still be supported for another 2 years*. Please take into consideration the work add-on developers already have done to get there classic add-ons working, give them significant time to switch to WebExtensions.

    In the mean time there should be a clear effort to get EVERYTHING (or at least 80-90%) of the feature set from classic add-ons working as a WebExtensions. (That means that No-Script, GreaseMonkey, Tab Groups should all work as an WebExtension). The 2 year path* (instead of 6 months), should be sufficient for add-on developers to migrate to WebExtensions is a natural way.

    At the moment is seems that add-on developers have to rush to get their extensions converted, which of course is never a good idea.

    *: Ideally this would be even longer, long time support would be 3-5 years IMHO.

    One comment about: “If you think your add-on can’t be ported due to missing APIs, here’s how you can let us know.” – This is ridiculous of course, based on the add-ons alreadt hosted at the Mozilla engineers are able to determine this themselves. The/all features used by these classic add-ons should be in WebExtensions before any disabling of the legacy XUL-based add-ons is done. (When then there are still options missing the developer of the non-AMO add-on can indeed indicate to Mozilla what is still missing).

    1. alex wrote on :

      “…based on the add-ons alreadt hosted at the Mozilla engineers are able to determine this themselves.”

      Given the dynamic nature of JavaScript, doing this would probably be equivalent to solving the halting problem.

      1. Kees wrote on :

        > Given the dynamic nature of JavaScript, doing this would probably be equivalent to solving the halting problem.

        Actually XPCOM isn’t that dynamic. It may be huge (as in theory a classic add-on can use all XPCOM components available). I’m not saying it is easy, but technically is can be done. Even an analysis (using every possible tool, even grep would do) of the top 10 most popular extensions will help a lot. (Although as indicated elsewhere the next step would be to check the top 100 extensions of course).

    2. kjemmo wrote on :

      I agree a lot in this comment.

      We have been encouraged to port to WebExtensions for some time now, but the truth is that for many developers it is still impossible due to missing APIs.

      I recently asked when a toolbar API will be available and so far no one has been able to give me a clear answer. Or the clear answer is “no one really knows” it might or it might not be available and no one knows when.

      I guess the answer is the same for several other APIs that are needed to port legacy extensions.

      Is incredibly frustrating with all this uncertainty.

    3. Termy wrote on :

      according to the developer of some of my favorite addons ( chrome://thefoxonlybetter/content/lastnotice.html ), i fully agree with you.

      I’m shocked that Mozilla is letting down/abandon one of the main reasons FF is loved and that sets FF appart from all the other browsers – most powerfull add-on options.
      I’m sure there’s a reason to switch to WebEx, but then WebEx should be feature-competitive to the “old” APIs and not missing so much that many addons can’t be ported over…

    4. Jorge Villalobos wrote on :

      > WebExtenstions is fine, however de-supporting the classic add-ons less then 2 years after WebExtensions is announce is wrong.

      I fully admit the timing was bad. The opportunity and resources to launch WebExtensions came up when we were already into the initial e10s migration process, and the plans for Firefox also shifted in a way that WebExtensions can be the only path forward. We can’t support legacy add-ons for 2 years more because the APIs they rely on won’t exist then. Supporting them for longer only means extending the frustration of constant breakage, both for developers and users.

      > That means that No-Script, GreaseMonkey, Tab Groups should all work as an WebExtension

      NoScript will definitely be a WebExtension. I know the GreaseMonkey devs were looking into it, and there’s TamperMonkey which is a somewhat equivalent WebExtension. Don’t know about Tab Groups, though.

      > This is ridiculous of course, based on the add-ons alreadt hosted at the Mozilla engineers are able to determine this themselves.

      Like someone else pointed out, this isn’t so trivial. We have tens of thousands of add-ons, some active and others abandoned, and the nature of the legacy platform means that there are no easily identifiable API points for most functionality. We have done some surveying and research, but hearing from developers who are still engaged in the process is the priority.

      1. Kees wrote on :

        > I fully admit the timing was bad.

        At least this is acknowledged, however that doesn’t change the fact that Mozilla is able to ensure that even with this very bad timing the rest of the process is done in a way that add-on developers (and users) have sufficient time to make a change. Especially when timing of a big change is bad (because Mozilla is doing something which will effectively destroys hours and hours of work done by add-on developers) the organisation should be VERY generous in giving the developers time to adjust to the new add-on type. Even 2 years may be too fast, but a certain date has to be set. (I can understand the need for an extension type which also works on say Servo, but as long a the engine is Gecko there is no need to *rush* to the deprecation/removal of the classic add-ons without a sufficient transition period).

        > We can’t support legacy add-ons for 2 years more because the APIs they rely on won’t exist then. Supporting them for longer only means extending the frustration of constant breakage, both for developers and users.

        This seems a management decision and not a technical one, the APIs exist today and can continue to be supported. Of course any change should be done in a stable manner, which may not be easy – however they have worked for years and letting them work (maybe without Fx in e10s mode) for some more time gives the add-on developers sufficient time to switch over in a normal manner.

        Even if WebExtensions would implement about 90% of the features of classic add-ons (which as far as I know doesn’t), a transition of 6 months is way too fast. Now that the WebExtensions are still forming 6 months is just asking for big problems. How would a user react when add-ons are no longer working because this was done on purpose (by removing the classic add-on support)? The will never be happy. Even if this affects 5-10% of the Firefox users this is to much, and I read somewhere that about 40% of Fx users has an add-on installed. Say that only 15% is really using an add-on which will no longer work, what will that do related to publicity about Firefox???

        > I know the GreaseMonkey devs were looking into it, and there’s TamperMonkey which is a somewhat equivalent WebExtension. Don’t know about Tab Groups, though.

        From what I’ve read about TamperMonkey is that this is not as powerful as GreaseMonkey (comment made by somebody elsewhere on a Mozilla blog [yes I know this is a vague statement :-)]. About Tab Groups, I’ve got an announcement from the developer that he will not be able to convert this and among the reasons was that WebExtensions is just not complete enough for this. In addition the current maintainer writes about the work he has already done to get his add-ons working with Firefox/e10s: “Oh, by the way, I already did all that. It took me a year and a half of extensive rewritting to make my add-ons e10s/multiprocess compatible, something that is being rolled out only now, all with the prospect of a long-lasting life for them. And the WebExtensions announcement was made not two months after. “Demotivating” doesn’t quite cover it…”

        The only comment I can add to this, that is that just because the developers already have invested lots of time into getting their add-ons compatible with e10s Mozilla has a moral obligation to give them a large time-frame (the 2-5 year migration path I suggested would do). Even 2 years may be short for somebody who invested 1.5 years in e10s compatibility – where most of it is spare time as well. 6 months is just way too short…

        About the fact that Tab Groups is no longer working on Firefox in the future is even more insulting to the person who took over its development. As it was Mozilla people themselves who suggest that Tab Groups is further developed as an add-on, somebody is taking this responsibility and about 1 year later Mozilla says effectively “well, thanks for the work you did, but it was all for nothing…”. Especially this add-on developer should have received all the help in getting the add-on working on WebExtensions (including the implementation of the right APIs and help from Mozilla to get the add-on converted – maybe this would even be a good show-case how the transtion would be done).

        >>> This is ridiculous of course, based on the add-ons alreadt hosted at the Mozilla engineers are able to determine this themselves.
        >Like someone else pointed out, this isn’t so trivial. We have tens of thousands of add-ons, some active and others abandoned, and the nature of the legacy platform means that there are no easily identifiable API points for most functionality.

        Well, I disagree with this (as this is not about JavaScript compatibility). As far as I know the core of the classic add-ons is based around XPCOM which in itself is fairly static technology. Even a simple grep in the 100-1000 most popular add-ons will give Mozilla engineers data to use. Instead of something relatively simple the burden is shifted to others (who did not necessary ask for this change). Of course there can be rough edges which will not materialize and for that input from developers will be helpful…

        After I placed the earlier comment I’ve browsed around a little and I did find the following overview (I know it is on a Wiki so not necessary up to date).

        When about 60% of the XUL/XPCOM APIs are not yet available as a WebExtension API then the first focus has to be to get this working…

        Instead of rushing in changes which require disabling the classic add-ons the Mozilla engineers should be working on getting WebExtensions to a point where at least the functionality is provided which you already identified. The next step would be to ensure that the APIs used by the top 100 add-ons (based on usage) are implemented and when that is done the removal of the classic add-on infrastructure should be done.

        Also one other note: It seems that the deprecation of the classic add-ons is not even done on an ESR version, this seems really strange to me. A change as big as this one should IMHO only be done in a way where people get a long transition period which is provided by an ESR release, but it seems that even something simple as this is not taken into consideration.

        1. liam wrote on :

          1. Mozilla does as you ask and, in two years time, has an unsustainably low share of the market. As a result, Mozilla, as a development entity, ceases to exist. Community picks up the remnants, but little is done with the codebase. Likewise, work on servo is halted, and the unique presence of a non-profit entity, with a strong market position, which advocates for a “more open web” is gone.
          2. Mozilla goes forward with a more sustainable codebase and is able to reach parity with edge, safari, and chrome when it comes to speed and security….perhaps this year. That progress comes at the cost of requiring extension developers to engage with the browser developers in a way that is unusual for both sides. This causes extensions to break, some developers to leave the community, and general unhappiness. However, a few developers continue their engagement and help define the webextension api and create an even larger gap of extensibility between Firefox and the other browsers.

          Yes, there are more options, but this is how each side views things.

          1. Nemo wrote on :

            What does “unsustainably low share of the market” even mean? Not enough revenue from the default-search provider due to low install base?

            How do you even imagine the cause-and-effect of “keeping XCOM on life support longer” to “plummeting market share”? The bulk of Firefox users don’t even INSTALL addons, so how is ‘people with crappy addons that cause instability switched browsers’ an existential risk to Firefox market share?

  2. Rockridge wrote on :

    It seems the release date of Firefox 57 is November 14th now. See RapidRelease/Calendar on MozillaWiki.

    1. Jorge Villalobos wrote on :

      Thanks, it’s fixed now.

  3. Eduard Braun wrote on :

    I hate how nobody at Mozilla ever even acknowledged “legacy developers”.
    If that’s really how important we are to you, then you’re going down with good reason!

    1. John Stein wrote on :

      They took on the herculian task of implementing both multi-process and WebExtensions in parallel, because it was clear that both would require a lot of porting work for add-on developers and they wanted add-on developers to be able to go straight to the multi-process-compatible WebExtensions, therefore having to only port things once.

      They implemented those multi-process shims just to give add-on developers more time to port their extensions. They serve no other purpose and, as mentioned above, will be removed from the code base once this is done with.

      They got into contact with some of the high-profile add-on developers who had extensions that couldn’t be ported to WebExtensions to work out together how the new APIs should look like. The closing words of this blog entry are a link for you to do the same.

      And WebExtensions are even just being added to Firefox, because it’ll mean less fixing work for extension developers whenever changes are made to Firefox.

      I’ll allow you the opinion that you’d rather continue fixing up your extensions, even when they get started with Project Quantum, or that you just don’t think WebExtensions are sufficient to replace the current add-on ecosystem, but do not claim that Mozilla never even acknowledged legacy add-on developers.

      1. safsadgfasgf wrote on :

        Just DON’t implement multiprocess. It’s slow and RAM consuming, it is not as useful as addon’s are. Don’t try to be Chrome, you cannot beat Chrome in what it is master: orientation on housewives and dumb people which saw ads on TV (usage of chrome is completely unmotivated, FF does everything better). Instead you will lose ff fans.

        1. Mark Smith wrote on :

          Wrong!!! Stop spreading lies! The browser is inherently insecure without multiprocess and exposes the user to severe danger and risk. Multiprocess and OS level sandboxing must become standard and mandatory features and eventually each tab must be contained within a seperate process. Most OSs support shared libraries so much of the browser code will be loaded once into RAM and then all processes would share the library code, this is a standard OS feature. State information would be in seperate processes. There is some work I understand to do on Firefox internals but multiprocess when implemented properly will have an insignificant effect on RAM usage. The effect on CPU is none, because a multiprocess browser will be able to run on multiple cores, it could actually utilize the 20 core CPUs that I hope we will eventually see. Doing multiprocess is essential to putting rendering and javascript code into a sandboxed process with a reduced kernel attack surface, no filesystem access. This protects the user should a buffer overrun happen, for instance.

          So, multiprocess and sandbox should become mandatory to protect users from malicious web pages.

    2. Joe Mindel wrote on :

      @Eduard Braun, what makes you so special that you have to be catered-to on some deeply personal level, and that Firefox will “go down” because they are not doing do? Legacy is a big problem to Firefox, and speaking as someone who has made such addons in the past, I can fully understand why Firefox would need to move on. I don’t feel like I’m more important than Firefox, and that addons that refuse to cooperate in order to keep Firefox relevant are of any importance in the longer-run. Users don’t care as much as you think they do.

      1. kristof nacsa wrote on :

        > don’t care as much as
        user here. from what I see it’s the other way around.

        my friends who used to use firefox 1-3 but wasn’t caring already switched to chrome at the time of version 4.

        if I look around me I see all over the place firefoxers who fall into two categories. 1) users who do care 2) users who take the recommendation from those in group 1.

    3. Jorge Villalobos wrote on :

      What do you think we should have done / be doing differently in terms of acknowledgement? We’ve been doing mass communications with developers for quite a while and are actually worried about being too spammy.

      1. Eduard Braun wrote on :

        There are in fact multiple things that make me currently hate Mozilla (and I used to be a big fan of the organization creating the Browser I once loved). As the deprecation of XUL is only one part of many I’ll not limit myself to that but try to paint you the whole picture:

        – It started around the time “Australis” was implemented. To the current day I detest that change (as did many others, including many of the most avid addon-developers). It’ no coincidence “Classic Theme Restorer” is one of the most popular add-ons. Mozilla never acknowledged that Australis might not be a universally good idea. Instead it was forced upon people with some changes unnecessarily breaking existing functionality.
        – There were good things, too: Hardware rendering (with serious problems in the beginning though), support for HTML5 and native video decoding, so I had hope.
        – Around that time Mozilla also decided to cut out many settings and “streamline” about:preferences. Instead of just hiding those settings they were usually removed without replacement. To the current day I don’t know if those were political decisions at Mozilla (“we don’t like it so you can’t use it”) or if it’s – sorry the term – incompetence (“we wanted to change it but now we can’t maintain the previous implementation, whether you liked it or not”) but it made me seriously doubt the path Mozilla was taking.
        – With all that on the table Mozilla started to implement new “features” (e.g. the new newtab page complete with ads, a redesigned downloads window, Pocket, pdfjs, Firefox Hello, …) I assume I should have been delighted about – but I wasn’t… It were things I don’t need (and I doubt many other people wanted), often not within the scope of a webbrowser, and with every step it was getting harder and harder to disable the stuff I didn’t ask for and to not let Mozilla decide “what’s best for me”.
        – By then I had the impression Mozilla was piece-by-piece stripping out the parts of Firefox I liked and was replacing theme with stuff I didn’t need or want. I wasn’t happy but – with the help of add-ons and userchrome.css – I was always able to revert the changes Mozilla had done and return Firefox to a state in which it was useful for me.
        – At the time Mozilla announced e10s I was a bit happier again. Finally a change that wasn’t useless for me. I was motivated and brought my (XUL) add-ons up to speed to be compatible. It was a lot of work but i had the feeling it was the correct direction. I even got an AMO editor around that time as review queues were endless and I wanted to give back.
        – Then the big downer: Before e10s even was close to hit a stable version Mozilla announces to deprecate XUL add-ons?!? That was basically a punch in the face. I just had invested a lot of time into my addons and into reviewing and suddenly Mozilla decides: All that work you’ve done will be trashed in about a year or two! Even if this was paid work I’d been furious, but it wasn’t. Quite the opposite as I spent something very precious: my free time.
        – Now I’d hoped for Mozilla to really explain *why* this step was necessary (thoroughly as it – hopefully – was discussed in internal meetings) weighing the cons and the potential gains, preferably with somebody personally taking responsibility (I guess you’ve got managers who signed off on this long-term strategy?) and explaining why it in fact *is* the correct choice. I would have hoped that the fact that this change will destroy the work of hundreds of volunteer add-on developers would weigh enough to really try to sell why the change was worth that. Instead all the mass communications where more along the lines: “We – Mozilla – have decided it’s time to move on. Thanks for your efforts but if you want to stay compatible you have to rewrite your add-on”.
        – Personally I therefore got the impression Mozilla does not appreciate add-on developers very much. I got the feeling that the drag of add-on compatibility was seen as an annoyance for only a “small bonus” in functionality. I did not get the feeling that add-ons were being recognized as offering real and significant improvements upon the functionality Firefox offers natively and could considerably impact the usefulness of the overall browser. Along these lines it also feels a bit odd that I never read once in a statement from Mozilla that they were actually sorry for breaking compatibility! Instead announcements where always quite technical explaining from a top-down perspective what needs to be done to stay compatible without even considering the real-world implications this will have.
        – For me personally it’ll probably mean the end of my add-ons. I don’t have the time to do a complete rewrite. Also I doubt it would even be possible to port all of them to web extensions. (Before people jump in again that I should specify what i need: This alone needs an awful lot of time! How should I be able to specify what APIs I need off-hand? This would already require me to learn a lot about webextensions, potentially starting to implement certain features. It’s unrealistic for many add-on developers! And even if I would: Wo could guarantee that the API for my super-specific use case will get implemented? But aren’t those super-specific use cases what makes add-ons really interesting?)

        I hope this made it a bit clearer why I’m so angry and I certainly hope that Firefox will continue to be a great browser but as I said so many times before: What advantages does Firefox have compared to e.g. Chrome if you take away add-ons and complete customizability? On the technical side you can never dream of beating Google’s developers, so all you have is your community! Don’t throw that away…

        1. bombless wrote on :

          Dude, you need to deal with the fact that Mozilla has limited resources.

        2. Lucumo wrote on :

          As a simple user who has been using Firefox from the beginning, I completely agree with you and thank you (and all other add-on developers) for all you have done for us. And yep, I had to install “Classic Theme Restorer” just to be able to properly use Firefox like I could before. Same with the “Downloads Window” add-on.
          I will probably not switch to the new versions…despite the recent update of Firefox often eating all of my memory when dealing with html5 videos.

          Apart from that, I’m with Celtic_superhero. Firefox should have stayed Firefox, instead of trying to become Chrome which they will never achieve. Throwing away all your advatanges, only to become an inferior copy…not the best decision. Might have been incompetence, might have been something else. Doesn’t matter, the future is looking grim.

        3. safsadgfasgf wrote on :

          You should also remember the case of forced self-firing of Aich. The nasty stuff occured after Aich have been fired. It looks like he was fired just to not to interfere with introduction of the nasty stuff.

      2. Salmon wrote on :

        Jorge, read carefully the paragraph in Eduard’s long comment above. The one that starts and ends with:

        – Now I’d hoped for Mozilla to really explain *why* this step was necessary …….etc etc……….. rewrite your add-on”.

        I and others ended up having to do that job for Mozilla, but it involves guess work, research, a bit of faith even, and a single news from Mozilla we have to start all over again.

        Just make a complete, thorough assessment as described by Eduard. It *is* needed, from the start of this project up to the reasons behind this very steep deadline as opposed to say, waiting Firefox 59 ESR.

        Additionally: More add-on developers need to be paid to port their add-on or implement their required API, like Giorgio Maone and Kris Maglione.

        Mozilla hear me out: You are cut off from your userbase. If you start to think you are being spammy, it really shows you are cut off. The problem is not there at all, the problem is that you don’t ever speak about the right things, honestly and in enough depth.

        1. Salmon wrote on :

          I also think Andy McKay is a WE extremist. I don’t question his competence and want him to succeed in his career, but he cannot possibly stay in a position that has such an impact on Mozilla PR when he is politically completely at odds with the vast majority of users affected by his work. The WE project can be achieved just as well with a more moderate leader.

          Completing what I said in my previous post: We don’t lie or affirm strongly things we are unsure about. That means we can’t do that job for Mozilla, we can only make readers more moderate and open, and only until your PR screw it up again by not explaining any of the things that should be explained. Honestly, just contact some guy with a good pen if that’s your problem, and reply all his questions, let him investigate as much as he wants and contact whoever he wants in Mozilla. Then he’ll do the post and follow up you’ve been failing to do all along.

    4. Liam wrote on :

      If webextensions don’t currently support an api you may be interested in this:

      Tldr, allows you to create an extension that will act like the api you need.

  4. Travis wrote on :

    You’re shooting yourselves in the foot by doing this.

  5. Fredrik wrote on :

    I for one am quite excited about all this! Will be looking to write some WebExtensions to help fill AMO and because the barrier to entry for me as a web developer is now lower.

  6. Amartel wrote on :

    I’m confused. Is there anybody, who thinks that killing Xul is a good idea?

    1. Liam wrote on :

      I’d imagine anyone who wants any of the following:
      Faster browsing
      More stable browsing
      More secure browsing
      Better platform to act as desktop alternative target (games, office suites, graphics and audio manipulation)
      More stable target for extension development

      Or maybe they’re just doing it for the lols

    2. Mark Smith wrote on :

      I think its a good idea. It will protect the users from malicious code. XUL is inheritently insecure and dangerous due to the level of access it gives questionable add-ons. There are problems as well with add-ons exposing users to threats from malicious web pages that could exploit a problem with an add-on. XUL was basically a dog and leads to all kinds of badly written extensions that creates a sea of possibly security exploits and poorly audited code.

      It will also also help add-on developers since they can re-use their code on multiple platforms.

      I kind of wish firefox could have kept XUL for older extensions only and required new extensions to use WebExtensions. But they have limited resources and they say major architectural changes will break XUL anyway, it would be extremely difficult or impossible to support older XUL extensions.

      1. Amy Tsay wrote on :

        Not sure if someone already mentioned this, but my understanding is that in the Nightly and Aurora channels, legacy add-ons will still be able to run via Experiments.

  7. Celtic_superhero wrote on :

    Soon starts the time where many before loyal users will make the switch to different products.

    Congrats Mozilla that you alienate users of accessibility and customisation featured – that way you loose even more soon.

    No one loves a rebuilt Firefox which is influenced by Chrome for Chrome users in mind.

    If you would be honest you would rename the browser – this is neither Firefox and you are no longer Mozilla. Mozilla was all about features and choice – you are no longer.

    Luckily Otter-Browser, Qupzilla, Brave, Vivaldi and others are carrying on old Mozilla’s legacy.

    Good riddance!

    1. jkoll wrote on :

      When Firefox loses its last advantage over Chromium there won’t be any reason not to use Chromium.

  8. kjemmo wrote on :

    I am the developer of a complex overlay add-on. For the past month or two I have been researching my options to port my add-on to a WebExtension.

    There are several APIs that are not yet ready, that I need before I can port my legacy extension.

    With just nine months to the release of Firefox version 57 I’m seriously starting to get concerned if I will be able to port my extension in time.

    The main problem is, that it is a date in time that dictates when WebExtensions will be the only supported add-on type.

    There are no list of minimum requirements or a list of essential WebExtensions APIs that must be available to developers before legacy add-ons are made absolete.

    That means that we as developers have no clue if or when the APIs that we need will be available.

    I have asked about this on the developer mailing list and here:

    And so far the answer is that no one really knows. There is no list of minimum requirements no one knows which APIs will be available and when.

    The strange logic is that a date will dictate when WebExtensions becomes the only add-on type and not a minimum set of features.

    You are just out of luck if an API that you need does not make it before the deadline.

    > We’ve been working on setting out a simple path forward, minimizing the compatibility hurdles along the way, so you can focus on migrating your add-ons to WebExtensions.

    I would love to focus on migrating my add-on to a WebExtension, but I can’t with the limited list of APIs currently available and It seems that no one can tell me if or when I will be able to do so…

    > There is a lot going on and we want you to know what to expect, so here is an update on the upcoming compatibility milestones.

    The truth is that we have no idea what to expect as there is no minimum requirements to WebExtensions.

    What I would like to see and what could give me peace of mind is the following:

    * A clear list of minimum requirements and APIs that will be available when WebExtensions are enforced.
    * A generous transition time of at least six months where all the minimum requirements above is available to developers.

    Without this we need to rely on hope and luck in order to port our legacy extensions.

    1. Jorge Villalobos wrote on :

      Can you please post this in dev-addons AT mozilla DOT org? I know that Andy McKay (who leads the WebExtensions API) is finguring out how to make that plan more visible, since now it’s mostly handled on Bugzilla.

      Now, the reason the deadline is a date is because there are many big changes coming to Firefox that will make legacy add-on compatibility pretty much impossible going forward. So, it’s not an arbitrary date we chose.

      1. kjemmo wrote on :

        I already did post this at the mailing list and Andy has replied.

        I suggested a list with planned APIs that are still in development in addition to the already available APIs. Here is my reply to Andy (have not heard anything back yet):

        “I suggest that a list of planned APIs is listed somewhere where it’s easy to find for WebExtension developers. It could easily be at the main WebExtension page:

        In addition to the already available APIs a list could be added with the ones that are in development and planned. Please see the screen shot for placement.

        Information such as expected availability (Firefox version) and a brief description of what it does would be great.

        With a list like this assumptions, hoping and guessing would not be needed and it would make it possible for developers to plan when and if to port their existing legacy add-ons to WebExtensions.

        Can anyone support this idea?”

      2. Kees wrote on :

        “There are several APIs that are not yet ready, that I need before I can port my legacy extension. With just nine months to the release of Firefox version 57 I’m seriously starting to get concerned if I will be able to port my extension in time. The main problem is, that it is a date in time that dictates when WebExtensions will be the only supported add-on type. ”

        I just responded to the reply Jorge Villalobos to my earlier comment. Above comment by kjemmo is a very good indicator (at least to me) what the current status of WebExtensions is: Still heavily in development and Mozilla requires from add-on developers to ensure that their add-on (most likely created in spare time) is working with Firefox 57 which will be prime-time 28th of November but for a significant number of heavy users (i.e. Aurora/Beta users) even earlier.

        To me the path taken looks like throwing away old shoes before the new ones are completely manufactured. The timing of the change should be longer (it will not help to alleviate the aggravation/anger of the developers who have invested in getting XPCOM based e10s add-ons compatible, but at least the ones who will go to the WebExtensions have sufficient time to make the transition).

      3. Kees wrote on :

        > Now, the reason the deadline is a date is because there are many big changes coming to Firefox that will make legacy add-on compatibility pretty much impossible going forward. So, it’s not an arbitrary date we chose.

        When the WebExtensions are not powerful enough then this deadline can become a dead for lots and lots of add-ons which may be the reason that people use Firefox. So instead of making internal changes which result in the removal of classic add-ons the real focous should be on getting the WebExtensions feature complete (i.e. in a state where a large number of features used by add-ons are available in WebExtensions).

        At the moment the checklist is not adding up:
        1. Feature is disabled just after an ESR release – nope it a couple of versions before. Should be a no-go.
        2. WebExtensions are already feature complete and tested. About 50% of the most used addons (say the top 25) are a WebExtension – I cannot answer this one, but to be honest my gut feeling says that this criterion is also not met.
        3. There is at least 2 years* between the first announcement that the classic add-ons will no longer work and the actual removal – doesn’t seem the case to me.

        *: I would like to have this longer, Mozilla would like to have this shorter so about 1.5-2 years would be somewhere in the middle….

  9. Rob Crowther wrote on :

    “Firefox 57, November 28th release”

    The sad day when, after 15 years, I will stop using Firefox as my primary browser.

    I’ve been able to work around all the previous dumb stuff only because of XUL-based extensions.

  10. DMcCunney wrote on :

    I’ve been using Mozilla code since it was still the code name of an internal Netscape project to replace Netscape Communicator with a next generation Browser suite, and I’ve followed along through Netscape 6 (unusable), Netscape 7, the Mozilla Suite, and Firefox and Thunderbird.

    I liked Mozilla products because of their extensibility. Having the UI implemented in XUL, CSS and widget sets meant I could dramatically change what the products *looked* like via themes, and change and extend them via extensions. I used Firefox because it was the most *powerful* browser.

    That has been steadily reduced. Themes now are at best title bar decorations of a basic UI that can’t be significantly modified. XUL is now deprecated in extensions, with pure JavaScript as the path going forward.

    Now we see Web Extensions as the anointed path for future development.

    I get the impression that the Mozilla devs live in an echo chamber, and only talk to each other. What *users* might need or want doesn’t seem to be a consideration. An example is the Australis redesign for Firefox. I didn’t mind it that much, and had already implemented a lot of what it did through extensions, but I saw a lot of “If I wanted the browser to *look* like Chrome, I’d *run* Chrome!” comments, and the complainers had a point. If Mozilla ever solicited comments from *users* about what *they* thought before imposing this, *I* never saw it.

    The changes outlined on the road map are steadily reducing the reasons I run Mozilla code in the first place. The use of Web Extensions going forward will likely *break* about half of what I have installed, because what they do simply can’t be *done* in Web Extensions unless that API is dramatically extended. (I’ve already gotten a notice from one developer of extensions that I use that development has ceased because he doesn’t see a way to do what his extensions do in Web Extensions, and they’ll simply stop working whan the switch is thrown.)

    Firefox appears to be doing its best to look and act like Chrome. Tell me, Mozilla devs – why should I bother to continue to use Firefox? Why shouldn’t I just give up and switch to Chrome, since it runs under both Windows and Linux and I dual boot? I’m aware of the architectural differences under the hood, but they largely don’t affect what I see and how I use the products.

    And I see the steady erosion in Firefox market share in favor of Chrome, so *large* numbers of users have already made that decision.

    Mozilla is funded by cooperative agreements with Yahoo, Baidu, and Yandex, so the money in Mozilla developer’s paychecks doesn’t come from actual product sales. But those agreements are predicated on Firefox driving traffic to those partners, and as Firefox usage declines, so does the benefit the partners derive from funding Mozilla. (And Yahoo has been acquired by Verizon and is being re-branded. Will Verizon see fit to continue the agreement? I’ll be rather surprised if they do. Then what does Mozilla do for funding? How many developers insulated from what the market wants will get layoff notices as funding goes away?)

    Mozilla seems to be totally out of touch with its user base, and declining steadily as a result. It doesn’t matter what your business model is – if you don’t *have* users, you cease to exist. That’s pretty much what I see happening to Firefox, and by extension, to Mozilla.

    Mozilla looks like it’s in the process of committing suicide, and is bringing it upon itself through utter failure to communicate with its user base and pay attention to what they want and need. It will likely be the source of some classic B-school studies on how *not* to run a project like that.

    I’m profoundly sorry about that, and I’ll continue to run Firefox as long as I can, but there will be a time when I can’t because it can no longer do what I want, and that time looks like it will be sooner rather than later.

    1. Mike Miller wrote on :

      I will stop using Firefox after version 57 is released as it just won’t do enough of what I need after that time. The extensions being exterminated are exactly why most people continue to use the browser.

      This is a terrible move by those who have lost touch with the main users of their product.

    2. Kees wrote on :

      > (I’ve already gotten a notice from one developer of extensions that I use that development has ceased because he doesn’t see a way to do what his extensions do in Web Extensions, and they’ll simply stop working whan the switch is thrown.)

      This could (and still can) be prevented by ensuring that WebExtensions match the feature set used by classic add-ons before the become the only option for add-ons.

      Just thinking out loud: Having compatiblity shims in classic add-ons would help with the transition so that you can have a classic add-on and use more and more WebExtensions when they become more and more feature complete. Of course the transition timeframe should be longer than 6 monts, it should be about 2 years or so…

      1. Jorge Villalobos wrote on :

        Embedded WebExtensions serve that purpose. But, like you said, the timeframe matters.

    3. sdfdfsdhgdsf wrote on :

      It’s we who are livin in an echo chamber. We are a minor share of people using Firefox. So in fact new Mozilla who lost the market to chrome because chrome is made on Google’s money and that’s why IMHO is near the fringe of bankruptcy. Cancelled projects can be signs of this. So they have 2 choices: try to retarget the product to housewifes (which don’t need extensions at all) making it more chromish and loosing geeks and get bankrupt, or just get bankrupt without any effort to prevent it.

      1. Jorge Villalobos wrote on :

        This report should give you a fairly good idea of how Mozilla is doing financially. Cancelled projects can also be a sign of better focus.

      2. Peter wrote on :

        Web browsing is a big part of my day and i use Firefox with , All-in-One Sidebar, Classic Theme Restorer, Clear Recent History, DownThemAll!, FlashGot, NoScript, Persona Plus, ProfileSwitcher, Ublock Origin and Status 4 Evar.

        These add ons make me productive. I have uninstalled Flash from my systems and have installed Google Chrome in addition to Firefox and switches to it whenever I need to use a site that still uses Flash.

        Google Chrome does not have a user interface and is therefore painful to use. I have tried to find ways of using Chrome to be ready when the “Australis removal of the Firefox UI” is completed but this has not worked for me.

        Google swiftly moved to an “Ecosystem” business model and us freedom loving folks are currently its subject. Mozilla understands this and launched its own Ecosystem play with big fanfare. Just as it started to look interesting they pulled the plug. They innovated with what many of us ad blockers found an acceptable level of intrusion with their ads on new tabs approach and just as we became accustomed to the idea that Mozilla is an ad funded enterprise they pulled the plug. Mozilla made ad campaigns where they proclaimed to be the defenders of privacy then got rid of Thunderbird. What is the mission of Mozilla and how is this expressed in practice.

        The world does not need a Chrome clone. Chromium is released under a free software license so the need for a free web browser is taken care of by Google.

        It seems that Mozilla’s reserves would be better spent on adding productivity supporting user interfaces to existing free software projects. It might be able to find a business model that is significantly different to Google’s and thereby be able to survive as a software project. Google’s business model is to insert itself into its users daily activities ruining productivity. The lack of a meaningful way of accessing bookmarks in Google Chrome is to ensure a round trip to Google search and another eyeful of ads when you want to visit your list of websites.

        The people that developed the original user interfaces to the Firefox browser got it right. The purpose of Google user interface design is to gain power over the user. Mozilla does not have a mobile phone where it can dictate terms to users, Mozilla does not have an equivalent to Chrome books where it can dictate terms to users. Mozilla does not have its own ad tech company. The only thing Mozilla currently have is its productivity aiding add-on ecosystem.

        What do we need Mozilla for? The only time a nontechnical user is subjected to Firefox is when a freedom loving techie installs it and instruct them to use it. What is Mozilla’s survival plan? Hopefully there are some really smart leaders working in the organization and they are just playing with their cards close to their chest. I’m worried please reassure me.


  11. Simon wrote on :

    Mozilla needs a shakeup in management – the decisions made are baffling. You are removing the only things that make your browser different. Why would anyone bother to download and install your product at that point when Chrome or whatever else that is bundled in is more or less the same. You cannot afford to marginalize your remaining base of users. WAKE UP!

  12. CuriousGeorge wrote on :

    I like this idea a lot. I find it frustrating when I develop a website for Chrome and it doesn’t work properly for the <10% of people who still use Firefox. Luckily, killing XUL will be the nail in Firefox's coffin, thereby fixing the problem.

    Thanks again to Firefox devs for their great help in moving everyone over to Chrome.

  13. tim wrote on :

    What about the Seamonkey-Version of the XUL extensions? Because that’s the browser to go, when firefox stops using XUL (as i guess they won’t migrate soon to another UI).

    1. Jorge Villalobos wrote on :

      As far as we know, SeaMonkey will continue supporting legacy add-ons for the time being. That might become harder in the future since SeaMonkey code is largely based on Firefox code.

  14. Neil Hunnernan wrote on :

    The only addon I truly care about is Firegestures. It is a XUL addon and there’s no indication it will be ported to Webextensions.

    EVERY mouse gesture addon in Google Chrome sucks. Most are literal malware, and the few that aren’t work frustratingly inconsistently. They simply don’t perform acceptably.

    I have seen no indication that mouse gestures will work well once Firefox murders its legacy addon system. When that happens I’ll either switch to the inevitable Firefox fork or Vivaldi. I’ve been using Firefox as my primary browser since it was called _Phoenix_, and you’re pushing me away.

    The vast majority of your community hates that you’re doing this, Mozilla. Response has been overwhelmingly negative since day 1. Most of us simply don’t understand why it’s necessary. Can you explain that?

    1. Jorge Villalobos wrote on :

      You can find an explanation in this blog post.

      1. Neil Hunnernan wrote on :

        Laughable. “Modernization” is not an explanation.

        As a user, this reads as “we’re doing it because we think it’s the best path forward”. That is your right as you own the product, but it isn’t actually an explanation.

        1. Jorge Villalobos wrote on :

          It’s a very long post, so I can understand if you didn’t read it all. The most relevant section is “Deprecation of XUL, XPCOM, and the permissive add-on model”, which goes over some of the technical reasons.

  15. Danny April wrote on :

    Jorge why removing customisation?

    It started already with Australis – the reason you removed that was not bc security – you can’t expect us to believe that it was for Sec reasons!

    Changing the UI is not compromising anyone at all. You did that bc you want to broaden your user base beyond power users. And bc users like Chrome or IE users don’t use a “bloated” prod – our pet features had to go.

    Oldskool Mozilla saw it as their obligation not to cater only noobs interests.

    What you are doing now is boing down to the lowest common denominator, supporting only amateurs interest. Opera did the same.

    It’s a shame you adopted a money oriented mentality which is a shame for an open source company. You are not better than Google or Microsoft – you are abandoning us for influence money and market share – and in 2 out of 3 points you are still failing.

    An open source project without user loyalty is not better than a close source one.

    Where is good old Mozilla and why it was replaced with that anti loyal and money and influence hunting imitation of a once proud and loyal organisation???

    1. Jorge Villalobos wrote on :

      There are some UI elements that are security sensitive, like the identity box, but that’s not the main reason that UI customization is being significantly restricted. The main reason is that add-ons that do this are very dependent on the UI begin a certain way, and breaking easily when it doesn’t. This means making big UI changes in Firefox (like Australis) lead to lots of anger from users and add-on developers, and add-ons end up being inevitably abandoned every time. Restricting APIs in a way that make them more future-proof largely avoids these problems. It’s a trade-off, of course, and some great add-ons can’t be implemented in the same way, or at all, but we believe it’s a net positive.

      1. Danny April wrote on :

        It is no one’s benefit you could have chosen to introduce UI customisation in bundled component or hard coded form. This is not about breakage – You do not want to support features like that any longer.

        Not going to use your browser any longer. Again we do not want a browser which looks like Chrome and works like Chrome. Hope you find enough replacement users BC one is for sure – without us vocal supporters you will have a hard time.

        1. Danny April wrote on :

          Here are some nice replacements for all who are fed up with Mozilla’s fascination with Chrome:

          Otter browser

          Jorge, how Google handles their UI is not at all desirable. Too bad you can’t understand that.

          Have fun in Chrome imitation land!

          1. G.V.P. wrote on :

            Some of those other browsers you mention actually use the Chromium engine. Pale Moon uses the Goanna engine which is based on the Gecko engine that Firefox uses. It is a fork that goes in the direction that firefox would have gone in if it hadn’t been derailed by Australis. Many FF extensions are completely compatible, and many developers have produced PM versions of your favorite FF extensions. Full themes are completely supported in Pale Moon, and that is not going away. You should check it out.

            Pale Moon dot org

      2. Donald Trump wrote on :

        You have to go back

      3. Ben wrote on :

        Why are you guys actively trying to destroy firefox?
        google paying you?

      4. Moo wrote on :

        “making big UI changes in Firefox (like Australis) lead to lots of anger from users […] Restricting APIs in a way that make them more future-proof largely avoids these problems”
        NOT MAKING such changes also avoids the anger. Also avoids a lot of work for everyone.

      5. Joe wrote on :

        It doesn’t really make sense to me that the solution to occasionally breaking a custom UI is to permanently break it.

      6. Catherine wrote on :

        Restricting APIs for the sake of “making big UI changes in Firefox” just makes me even more scared to stay on the Firefox code base. Australis was something that felt forced down our throats and, indeed, did break a lot of my own personalization work. I switched to Waterfox when you began injecting Pocket and Hello. I hide in Stylish with Australis. Once XUL is removed and I lose ownership over my interface yet again, I’ll be forced to abandon the last browser that offers any sort of unique control. I had been holding out, hoping this decision might be reversed, but that seems to not be the case. Time to freeze updates till I can find an appropriate replacement.

  16. Afdal wrote on :

    All I can say anymore is that I really hope the Animated PNG format continues to thrive without Firefox behind it to encourage adoption. It would be tragic for that to become a casualty due to the poor choices of Mozilla executives intent on killing their own user share. Maybe Pale Moon will rise to fully replace Firefox.

    1. kristof nacsa wrote on :

      I hope Mozilla releases a new brand dedicated to XUL+XPCOM,
      until then yeah is your place to go,

      I gather they did a really good job forking Gecko the Firefox engine to Goanna, Pale Moon superb browser choice let it live long either way!

  17. Ken Jameson wrote on :

    Mozilla – you have one big problem!

    The issue is that you are always in attack mode and you are willing to fight! You are doing that since day one. You tried to fight against IE and have been able to break it’s dominance a bit with useful and cool features.

    The Chrome arrived. You tried the same strategy too, but it was not working as it used to work in the past. So you have been thinking about something else. Beat them with their own weapon. If Mozilla would walk away from their attack mode and would accept things as they are, it would not have ended like that. But your newest plans are also a total failure. So why still going on with that. You had a nice market share during Firefox until version 20 or something like that. Enough to shove it into Google’s face and make them realize that they are not winning to 100%. But even that was not enough or you guys. You wanted to become number one, no matter what it has to be done to reach that goal. For this you are sacrificing user’s interests.

    History has showed it that crusades never will lead to success. We had already crusaders being beaten up for being ignorant and power hungry. And that’s what you are too. You are crusaders on a holy war for influence and breaking the dominance of Google Chrome. But if you betray your own user base for this fight, you are nothing better than the enemy you want to take out.

    Learn history Mozilla, we already have been there. Aggressive and horrific crusades never will lead to success. We had a religon crusade which failed. We had during WWII a crusade and it (luckily) failed. What makes you believe that you win your crusade?

  18. Adam wrote on :

    For years now I have written extensive comments on this blog in response to Mozilla’s foolish decisions, especially regarding addons. They were in vain, however, since Mozilla is intent on transforming FIrefox into Chrome and thereby destroying itself.

    I’ve used Firefox since it was Phoenix. Firefox 56 will be the last version of Firefox I use. May the Phoenix rise again.

  19. meee wrote on :

    Welp, looks like the final reason why I still use Firefox as my browser will be gone in November. You served me well for many years, but your time has come. Goodbye.

  20. z wrote on :

    There is no reasonable alternative to Tree Style Tab and Suspend Tab so I will probably be switching to Chrome

    1. Jorge Villalobos wrote on :

      Tree Style Tab is my favorite add-on, and I hope the developer will have a suitable WebExtensions version by the time 57 arrives. He’s been involved in proposing WebExtensions APIs.

  21. Danny April wrote on :

    Bye Jorge I hope you and me or I and another Mozilla guy will never meet each other – because I feel VERY motivated to belt you one right in the face!

    You guys are spineless betrayers and Google fanboys.

    1. Buttman the Dark knight wrote on :

      That’s enough, Danny / Celtic. You’re acting like a spoiled kid who is owed everything. You don’t get to threaten people, lightly or not, and not be called out for that.

      1. Lestat wrote on :

        So speaks one of the guys who does not care for special features. Mozilla should not surprised to get that gate because if they allow it to happen that Google gets into the position to dictate what Mozilla is creating and destroying then Mozilla has to endure it because a Google controlled company does not earn anything better.

        Mozilla today is nothing of value. Opera today is nothing of value. Both companies are infiltrated and taken over from a third party.

        Mozilla does not earn something better and they should be happy that people only are cursing them, after all they have done and after all that betrayal of us customisation loving core users they for sure earn a date much worse than that.

        Who has no respect and loyalty against the users who made one big and mighty most of the time gets it in the end.

  22. Mark wrote on :

    Due to you guys dropping XUL addons, I’m dropping Firefox from my desktop, android and laptops. All that made Firefox great is being removed by you, so there’s no point in using Firefox anymore. I really hate the fact that these decisions have been made, and hope that you will see the light one day. But until you do, I don’t want to have anything with you, your browser, and yoir brand anymore. Goed luck “making the web great again” — you’re ruining it for me. So I’m breaking up with you, farewell.

  23. togetfiles wrote on :

    An educated, highly efficient, and well organised public on the net, is obviously NOT the intention of the Mozilla creed.

    Spare us the morbid liturgy and fake sermons Mozilla. Mozilla is 100% a political cointel movement and it’s time the alternative people to do themselves a favour and see Mozilla for the snakes they are.

    I’ll welcome a M$ browser any day of the week.

  24. Cyrano wrote on :

    Hi Jorge,

    Could you please share, if available, a link that details the scope of WebExtensions APIs related to UI ? I mean, what is the list of design constraints that an UI API must pass to be accepted and added to Firefox ?


    1. Jorge Villalobos wrote on :

      I suggest you send that question to dev-addons AT mozilla DOT org. I don’t know if there’s a clear list for this, but here’s what comes to mind: 1) should handle radical UI changes well, or fail gracefully, (2) should be fully asynchronous (since WebExtensions will run in separate processes in the future).

  25. Stephen Fordice wrote on :

    Thanks for pushing me to use Opera. Faster, cleaner, better. Goodby Firefox, have fun with the broken browser.

  26. KellyL wrote on :

    So… what is wrong with Mozilla lately?

    The issue is that they are always in full attack mode and are willing to fight! They are doing that since day one. Mozilla tried to fight against IE and have been able to break it’s dominance a bit with useful and cool features.

    Then Chrome arrived. Moz tried the same strategy too, but it was not working as it used to work in the past. So they have been thinking about something else. Beat them with their own weapon. If Mozilla would walk away from their attack mode and would accept things as they are, it would not have ended like that. But their latest plans/goals are also a total failure. So why still going on with that. Moz had a nice market share during Firefox until version 20 or something like that. Enough to shove it into Google’s face and make them realize that they are not winning to 100%. But even that was not enough for them. Moz wanted to become number one, no matter what it has to be done to reach that goal. For this they are sacrificing user’s interests.

    History has showed it that crusades never will lead to success. We had already crusaders being beaten up for being ignorant and power hungry. And that’s what Mozilla is facing too. They are crusaders on a conflict for influence and breaking the dominance of Google Chrome. But if they betray the own user base for this fight, they are nothing better than the enemy Moz want to take out.

    Learn history Mozilla, we already have been there. Crusades never will lead to success. We had a believe driven crusade which failed. We had a war driven crusade which failed (luckily). What makes Mozilla believe that they win their crusade?

    Also to count into is the following:

    Jorge made it more than clear that ui customization is no longer a supported functionality!

    Mozilla mentions also quite often maintenance or security reasons for removing features.. but the truth behind which everyone knows is the following:

    Maintenance and security is a reason, but not the biggest. The thing is simple users are representing the biggest part of the market share. Chrome owns the largest percentage of the market share.

    So what do companies do which try to gather a large part of that users too? They restrict and remove features from which they know that simple users are not going to accept them and refusing to use a browser with such features inside.

    Opera has done it. Even Microsoft has done it partly with Edge – even if they can’t remove much features as they do not had many in the first place. Everyone adopts that new simplicity trend because big companies show that they earn that way money and gather large influence. Even an Open Source company like Mozilla is not willing to ignore that.

    Ask a simple user if he would use a software with customization and tons of accessibility features inside. The answer is a clear no-brainer. And what are you doing then to gather that users? Kill features and restrict the feature set until a point that these users switch over.

    Saved money is a nice side effect, but not the main reason of all that. Like it or not, we experience a 180 degree shift of priorities. And in most cases advanced users are the one’s who lose everything as it is not possible to earn enough with users like us today.

  27. John Nagle wrote on :

    So Mozilla is killing Jetpack, the Add-On SDK, too. After pounding add-on developers into using it.

    The question now is, does Mozilla still have enough market share to justify conversion. My add-on usage has dropped 50% in the last year, in lockstep with Mozilla’s declining market share (6.58% in January 2017.) Should we bother?

    1. Sup wrote on :

      Firefox desktop: 350M users
      Firefox for Android: 170M users
      Firefox for iOS: Dunno
      Rough total: 500M users not accounting for iOS.

      Your call.

  28. Leigh Harrison wrote on :

    I’m a web developer of more than twenty years, and a Firefox user since it was first available. My development ecosystem is based on Firefox with a specific set of extensions. Through cross-browser testing I know I can get some (but not all) of this ecosystem’s functionality in Webkit browsers. For the remainder I have to rely on external applications, which makes for a less efficiently integrated workflow.

    Pragmatically, if a new release of Firefox arrives and I can’t update my preferred extensions to maintain the development ecosystem I need, I will switch browsers. Hopefully there will be a Firefox fork available, but I can’t afford to be picky: my income depends on this functionality.

    I’m prepared to trust that Mozilla is making this move for sound reasons. But the day it affects my ability to do my job efficiently will, with regret, be the day another browser replaces Firefox as my tool of choice. Nothing personal; I want to see Firefox succeed, but I have to earn a living.

    Best wishes,


  29. J wrote on :

    Mozilla doesn’t know what to do. They change plans like people change underwear. Forget about this browser already.

  30. Eric wrote on :

    Looks like the various tab customization extensions won’t work at all with the new extension system. That’s a shame, I’m a long time Firefox user and a huge fan of vertical tabs.

    For those of you looking for an alternative browser with a highly flexible UI, I’d definitely recommend checking out Vivaldi.

  31. Janne Koschinski wrote on :

    So, here we are now.

    A deadline has been set, deprecating that what gave Firefox once its edge over the other browsers.

    The question now is, can WebExtensions ever live up to what it has to?

    Will we be able to actually modify the entire browser chrome with HTML and CSS someday? There still isn’t any API yet to add toolbars. Nor is there any API allowing us to add tab thumbnails as previews (as known from Vivaldi).

    We have no way yet to port code like Automatic HiDPI (an addon that allows Firefox to handle HiDPI on Linux, with different scaling factors per monitor).

    Nor is there any way to port many other addons that I and many other rely on daily because the Firefox Core itself is missing many features, and others are massively buggy, but suggested changes are ignored by Mozilla.

    So, for me, this is probably going to be the end – without these addons, Firefox is unusable for me (as the DPI scaling still is a massive issue), so I’ll have to stop using Firefox at all.

  32. ngiau wrote on :

    I totally understand the importance of multiprocess. Maybe there is no good decision to stop losing users at this moment since most of the users know nothing about these and will simply choose Chrome because Google is good. But certainly you can not lose the customization as that is your advantage and that is why your hard core fans choose you. Doing this will accelerate the decrease of market share.

    Moreover, imitating Chrome is even a worse idea. How could users of Chrome switch to a Chrome-like stuff I can imagine that in a few years, Gecko will be replaced by Blink and about:config will be deprecated. Then in one day Chromium instead of Firefox will finally become the default web browser in Linux distributions. Then RIP.

    I will try Pale Moon, as that is what Firefox should be. I might still keep Firefox on my computer as a secondary browser, but from now on, Firefox is nothing special to me.

  33. anon wrote on :

    Contrasting many it seems, I’ve just switched to firefox for privacy. Removing the old addon system was justified by mozilla as necessary to implement better browser security. With the use cases browsers handle, sandboxing and guarding against RCE takes priority over convenience of some addon users.

    I, for one, fully support mozilla’s decision to kill off the old addon system if it’s holding the browser back.

    Also, attacking people for doing something they are within their rights to do is down right pathetic.

    1. Lestat wrote on :

      Perhaps for simple users is a bit more feature rich than Chrome enough but for many users it’s not.

      Especially if it is more than clear that it is not about security first but because is broadening the Firefox userbase in simple/Chrome users direction.

      To start all the issues with features started when Mozilla removed them in Australis.

      Then stuff was breaking as CTR had to deliver what Mozilla refused to do in version 29.

      And now they use this excuse to restrict customisation abilities once more.

      People have all rights to be pissed. All this is a decision against power users. Why? Because Opera did similar. Mozilla has no right to abandoning it’s feature loving core usergroup.

  34. Joe wrote on :

    To me WebExtension is the way to go, but when it is reacher than Chrome’s one. Not when it is a lot less powerful. Firefox needs to have something that attracts people to it. If the idea is to follow Google, then why not using its browser as well? Why anybody should be interested in Firefox?

    I know you guys want to extend WebExtension, but at least until FF 57 is released, there is no way for WebExtension to be more powerful that what Chrome already has. This means users are get better support if they dump FireFox and switch to Chrome, right? Normal users wouldn’t return back to Firefox if they can get what they want in Chrome.

    This timeline you propose will definitely affect Firefox. I do understand the need to move to WebExtension, but it is clear at this stage WebExtension is not yet powerful enough for most of developers and hence they will give up supporting Firefox. For instance WebExtension has no plan for supporting access to password manager, does this really mean all password related extensions are going to die?

  35. Elis wrote on :

    What about tree style tabs?

    1. Jorge Villalobos wrote on :

      The developer has been fairly involved in WebExtensions API discussions. It’s my favorite add-on, so I hope it will make it by 57.

  36. Anon-a-moose wrote on :

    Whelp that’s it for me. Moving on to Pale Moon already. So long Mozilla!

  37. Keith Hall wrote on :

    How can one tell which extensions they have installed are WebExtensions and which are legacy extensions? Why doesn’t display this information?
    I’d like to know which addons I could potentially lose the use of in November…

    1. Jorge Villalobos wrote on :

      We don’t expose that on AMO at the moment. But we’re working on a recommendation system that will let you know if an add-on won’t make the cut and what your available alternatives are.

  38. Alex Smith wrote on :

    Please Mozilla – reconsider this approach. As Firefox users, we want our browser to have the best technology, but not at the expense of our ability to use add-ons vital to our workflow.

    XUL, etc. should only be replaced once there’s a viable alternative in place. Anything else will cause the mass migration of Firefox power users who rely on Firefox’s best and most powerful feature – its ability to be customized to the user’s needs.

    If anyone cares about this, I’ve created a petition here to see if we can get Mozilla to reconsider:

  39. smith wrote on :

    I need legacy addon.
    I don’t wish WebExtension addon.
    If WebExtension addon are adopted and legacy addons are obsolete, I will cease updating with firefox 56

  40. Patrick O’Keefe wrote on :

    As with most Firefox users, I know absolutely nothing about developing FF add-ons. I care nothing about developing FF add-ons. I just use them. And I am not going to be happy when those add-ons no longer work. As with most FF users, I knew nothing of this upcoming change. I saw mention of it in a Win10 forum, and I’m certain most FF users do not look at Win10 fora. I suspect most FF users are going to be blind-dided by this change when FF 57 is released. This is not a good way to keep customers.

    1. Amy Tsay wrote on :

      It depends on which add-ons you’re using. I wouldn’t expect all of your add-ons to stop working. For the ones that would no longer work, we’re planning to recommend alternatives with similar features.

  41. Gumbo Bakalaclaque wrote on :

    What is the way to go now?
    Rewrite my addons for Vivaldi browser?
    Keep going and hope there will be a Firefox Fork with a good community and XUL Addon Support?
    Stop this and do meaningfull stuff for thankfull people?

    I think Firefox will be dead soon with this anti customization policy.

  42. kristof nacsa wrote on :

    Mozilla, hear me!

    restore XPCOM and XUL
    keep the users who loved wrote and used addons for 10+ yrs

    webextensions is the actual insignificance
    this is because you can already have other browsers that have webextensions
    there is no purpose in Mozilla going that way

    please, fork your product and create a firefox brand which will work forever with XUL and XPCOM.

    should you go webextensions, you will loose your users, trust, and eventually fade away.
    the only value it gives you is when you sell out the company to people who doesn’t care about it.

    you don’t have to do that – firefox the XUL+XPCOM way is something that still gets the love. from the users that is. you can’t get back the users who left for chrome after version 3 to 4 but you can keep your loyal die-hard firefoxer base if you keep XUL+XPCOM.

    Thank you!

    @commenters: here is a petition you can sign (I am not affiliated, but I’ve signed):

    1. Mark Smith wrote on :

      As I have said elsewhere, I do think XUL and XPCOM should be depreciated and phased out. They are too insecure and dangerous and expose the users to malicious code in the add-on or to malicious code coming from web pages. To say you want to keep this indefinitely is insane, its just naive disregard for the safety of users.

      However, I did post previously suggesting that for *existing* add-ons XUL and XPCOM could be kept and only new add-on would have to move to WebExtensions. They replied that the architectural changes coming would break XUL and XPCOM anyway.

      1. kristof nacsa wrote on :

        Hi there Mark!

        > please, fork your product and create a firefox brand
        please just do that

        > which will work forever with XUL and XPCOM.
        where I said “forever”, I’ve really meant “dedicated to”.

        release a new brand dedicated to xul+xpcom
        not unlike Mozillians released Seamonkey for those who
        wanted that sort of thing. repeat this step and release
        a brand that is dedicated to xul+xpcom for those people
        who just want those sort of things.

        you don’t have to agree with it, just let be *Mozilla* release it:
        those who want that sort of things will take care
        for themselves.

  43. Michael wrote on :

    Your plans are fine.
    Your timeline is the biggest nonsense you could have come up with.

    Give yourself more time to implement a hell lot more APIs.
    AFTER(!) that give us more time to port.
    THEN(!!) kill legacy add-ons off.

    1. kjemmo wrote on :

      Spot on.

      I do not mind WebExtentions, but forcing WebExtensions before the API is ready is simply nonsense.

    2. Grzesiek wrote on :


      I don’t care about legacy technologies. I care about features. If my must-have addons* keep working, everything is fine.

      * These are:
      – Tab Groups
      – Tab Mix Plus (actually a rather small subset of its functionality)
      – HTTPS Everywhere
      – Transparent standalone images (this addon is super simple and I plan on porting it to WebExtensions)
      – something to disable the “Ctrl+Q means quit” shortcut
      – something to block ads, trackers, fingerprinting and other crap.

  44. Bill wrote on :

    November 15th: 80% of Firefox’s userbase asks themselves why they should stick to this browser because it’s still good but now lacks its unique selling proposition.

  45. kwhitefoot wrote on :

    Apart from wanting to support an open source browser the (on my own gear I try to have only open, preferable GPL, programs) the only reason to use Firefox is add-ons of various kinds.

    If major add-ons like GreaseMonkey disappear all that will be left is the warm fuzzy feeling of supporting software freedom. But if I have to use another browser anyway to get the customisation that I want I probably will end up with Chrome or something that depends on Chrome anyway so then I lose even the warm fuzzy feeling.

    For the moment all I can do is wait and hope

  46. Mark Smith wrote on :

    I am in full agreement that the old XUL based add-ons system needed to be eliminated and replaced with something far more secure. Something which allows the data in the browser to be accessed directly by the add-on and this data to be possibly sent or transmitted is very insecure. It is actually pretty annoying hearing of add-on developers who extol the virtues of such a dangerous and insecure model which encourages an environment that endangered user security and welfare. Add-on code which can look at user data should not have any contact with the outside world and should not be able to transmit this data to the outside world. All add-ons should have to use the browsers file save dialog as well so the add-on has no ability to directly read or access the filesystem. They all must run in a sandbox.

    The flood of thousands of add-ons to Mozilla and the fact that Mozilla runs an add-on repository creates a situation where users assume these add-ons are safe. In fact, they are exposing the user to possibly malicious code. XUL sounds like a security nightmare. I can imagine that trying to audit such a large number of plugins was becoming a huge logistical problem.

    Firefox for years was the most insecure browser due to XUL and due to the lack of a multiprocess sandbox. So, its good to see Firefox finally starting to catch up with the other browsers in protecting users from the hostile and dangerous web environment.

    Firefox did what was right to get rid of XUL and finally do multiprocess and sandbox, and to promote cross browser compatability by supporting the same add-on API as the other browsers, which will actually help add on developers.

    It is upsetting to hear so many people who have such a naive disregard for user security and safety to want to continue to expose the inheritently insecure and dangerous XUL and browser internals to a sea of questionable third party add-ons. Add-on writers need to move on from the broken insecure old API and rewrite for WebExtensions.

    1. Jorge Villalobos wrote on :

      To be fair, WebExtensions (and extensions for other browsers) can still access user data and send it to remote locations. Granted, some of that data is gated behind permissions, so users need to approve it, but it doesn’t apply to all kinds of data. And there’s no separate permission for web connections, since it’s such a common feature for extensions and the web. That’s why we still do code review for WebExtensions on AMO.

      Having said that, there definitely are security and stability benefits in WebExtensions, and we really appreciate the support.

    2. Repo wrote on :

      That means killing also almost every bit of ui customization.

      That is not a good trade-off. This is only supporting the most rookie user base. After Mozilla removed customization from the UI with Firefox number 29 add-ons have been our only choice to customize the UI.. and now that is going away too.

      With Webextensions something like CTR is not possible anymore. Ask the developer over at Mozillazine.

      That security aspect is a large joke. The truth is that Mozilla decides that a different, more simpler user base is of more interest than us power users today.

      I and many others will not support that, that it will be no longer possible to move buttons on a large scale, that we can’t have custom toolbars anymore or that we can’t combine bar elements into one single bar.

      All this is going away. And why? Mozilla believes no longer in features and advanced users. One more time, that security aspect is a joke. XUL could have been made more save and it is actually save.

      Firefox with webextensions does offer nothing to advanced and power users. Firefox users are adults, we know what we are doing. We are no infants which needs a caretaker. We used and loved Firefox because of the options which have been offered to us.

      Now almost 100% of it is going away. Here is my answer: uninstalled! We do not want a browser which works like Chrome. We do not want a browser which looks like Chrome. Because we already have Chrome.

      We need features and options and choice and not lame limiting Google technology which is not allowing us to customize the browser in a large scale.

      Talking about security is the most biggest lame joke ever. Thanks for nothing. Like Opera Mozilla is now just another failed company which believes more in what Google does than actually in what they have done in the past.

      This is selling-out and giving up. I will not be a part of that limiting future. Why not offering replacements like Vivaldi does it? Here is the answer: Because Mozilla does not want to have customization features inside the core product anymore. Taking away the only remaining options too is the most shameful and disappointing thing what Mozilla ever has done.

      Btw. i take away the over 100 users i brought over to Firefox in the past with me, to whatever for a browser i am moving. That happens if you mess with power users. You get a reaction.


  47. Drozo wrote on :


    Do you know if Rikaichan’s developer is involved in a WebExtension port ?
    If you don’t, do you know if Rikaichan’s features have a chance to be turned into WE APIs ? Or better yet, Rikaisama, which is a fork with much extended features.

    1. Jorge Villalobos wrote on :

      I know the developer is active and has been working on e10s compatibility for the add-on. I don’t know if they have WebExtensions plans, but the add-on seems feasible to port.

  48. AjangP wrote on :

    Regardless of anti-virus/malware I used, my computer had been attacked by malware twice, which I believe coming from downloaded applications. The malware immediately spread and infected all browsers I have but Firefox, which is the reason I always keep Firefox even though it now may lack of unique selling proposition.

  49. Linards wrote on :

    Thanks! Nice to know the milestone!

  50. Anon wrote on :

    Will userChrome.css and userContent.css still be working in Firefox 57 and up?

    1. Jorge Villalobos wrote on :

      I don’t know of any plans to remove support for them.

      1. Gary wrote on :

        It is my understanding that using css code to modify the UI won’t be allowed. If true what can a person place in userChrome.css that would be allowed?

        1. Jorge Villalobos wrote on :

          As long as it is supported, you can add any CSS like before. You just won’t be able to do it from an add-on.

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