Firefox OS Simulator 3.0 released

About 6 weeks ago, we wrote about the preview of Firefox OS Simulator 3.0 and now we’re happy to release it!

New features

In our preview coverage, we listed the new features for this version:

  • Push to Device
  • Rotation simulation
  • Basic geolocation API simulation
  • Manifest validation
  • Stability fixes for installation and updates to apps
  • Newer versions of the Firefox rendering engine and Gaia (the UI for Firefox OS)

Since then, apart from verifying and making the above functionality stable, other notable improvements are:

  • Keyboard shortcut to repackage/reinstall/restart the current app – drastically improving workflow speed, especially for packaged apps
  • Significantly reduced download/installation size of the Firefox OS Simulator
  • Faster start time (partly due to above with smaller size)
  • Much newer versions of Firefox OS and Gaia
  • General bug fixes, making it more functional and reliable
  • OS-standard ways in the menu to close the Simulator, with corresponding keyboard shortcuts (Alt + F4 on Windows, Cmd + Q on Mac, Ctrl + Q on Linux)

Firefox OS Simulator documentation

As part of this release, we’d also like to highlight our updated Firefox OS Simulator documentation on MDN and also our Firefox OS Simulator walkthrough example.

Download/install the Firefox OS Simulator

You can download version 3.0 of the Firefox OS Simulator from our add-ons web site.

Please let us know what you think in the comments! If you encounter any bugs or problems, please file a bug.

About Robert Nyman [Editor emeritus]

Technical Evangelist & Editor of Mozilla Hacks. Gives talks & blogs about HTML5, JavaScript & the Open Web. Robert is a strong believer in HTML5 and the Open Web and has been working since 1999 with Front End development for the web - in Sweden and in New York City. He regularly also blogs at and loves to travel and meet people.

More articles by Robert Nyman [Editor emeritus]…


  1. Mike Rogers

    With every update I’m getting more and more exciting about the impact Firefox OS will have.

    I can’t wait to start building apps for it.

    May 2nd, 2013 at 10:45

    1. Robert Nyman [Editor]

      Sounds great, Mike!

      May 2nd, 2013 at 13:39

  2. Piers Hollott

    Thanks Rob!

    I’ve been working on a Mobile Health connectathon demo; I’m particularly excited about the updates to the Gaia apps, since I’m integrating with the dialer.

    May 2nd, 2013 at 14:21

  3. Nico Steiner

    Firefox OS in my opinion would perfectly fit together with – right now they are not sure whether to start with Firefox OS or not – I press thumbs!

    May 2nd, 2013 at 14:37

  4. schoewilliam

    That is great ! I’m really really exciting about Firefox OS and begun to try writing a notes taking app. The simulator 3.0 already helped me a lot.

    May 2nd, 2013 at 19:29

  5. Tomer Cohen

    Why not have it run in its own browser tab, instead of running on a new window? We can also allow it to run in full screen, which is great for demonstrations.

    May 3rd, 2013 at 04:33

    1. Myk Melez

      A browser tab would be ideal, but the Simulator has to run in its own window due to a technical limitation of the current implementation (which runs in a separate process using its own Mozilla profile). It might be possible to overcome that limitation eventually, but it would probably be a lot of work.

      May 3rd, 2013 at 08:51

  6. Maiko Engelke

    Indeed incredible, but just one question. I actually never tried cause I feel it won’t work, and I also bought the Peak, so when I get it I know I will be able to do it, but does the simulator supports APIs that won’t be made for the Desktop and Android Apps, like TCP Sockets and such?

    May 3rd, 2013 at 05:16

    1. Myk Melez

      Good question! I’m not sure how the Simulator’s API support compares to desktop and Android at the moment, but in general I think our goal is to support the same APIs on all OSes on which we implement a runtime for Open Web Apps (except where it isn’t possible due to hardware differences). That includes FxOS, Android, and desktop OSes.

      So the Simulator isn’t designed to support APIs that won’t be made available for non-FxOS devices. However, it might still be the case that it supports some such APIs, because we’ve implemented the APIs in FxOS but haven’t yet implemented them on the other OSes.

      May 17th, 2013 at 11:33

  7. viswaprasath

    Is IMEI facility has been added to this simulator.
    that is can i get the IMEI of the device now. any random number as it will act as IMEI

    May 3rd, 2013 at 08:37

    1. Myk Melez

      No, we haven’t added the ability to get the IMEI of the virtual device. I’m not sure there’s even such an API on real devices, at least not one that is exposed to apps. The WebMobileConnection API docs suggest that there isn’t one, but it could be out-of-date, so you might try asking in the B2G forum. However, any such API is likely to be available only to certified apps (i.e. those that come bundled with a device).

      May 3rd, 2013 at 08:59

  8. Brian LePore

    I’m having some issues finding a change list. I swear that previously Firefox OS used the largest image with a rel=”icon” when you try to add a web page bookmark to the home screen, but now it seems to use the last one referenced. I serve two images sized at 128 and 256, and then a favicon after it. The favicon is now being pulled, but I swore it wasn’t like this in the last version of the simulator.

    May 3rd, 2013 at 10:12

    1. Myk Melez

      Here’s the comparison between Simulator 2.0.1 and 3.0. But it seems more likely that the behavior you observe is in the Gaia, so here’s a comparison between the versions of Gaia in Simulator 2.0.1 and 3.0. (It’s also possible that the change is in the B2G codebase, for which I don’t have a good comparison at the moment.)

      Those comparisons are large! So you might have better luck reporting a bug in B2G, providing your website’s URL, so folks can test on real devices. If you do that, please cc: me (putting :myk into the CC field will do it) so I can keep tabs on it.

      May 3rd, 2013 at 10:31

  9. Murdok

    The success or failure of S.O. depends on having the most popular app.

    * Line
    * whatsapp
    * shazam
    * apalabrados

    * …….

    Firefox will not currently have them.
    There are plans to incorporate these app. ??

    May 6th, 2013 at 10:44

  10. Zakir

    Is Firefox going into the tablet market too as I would love using Firefox os on a touch screen tablet

    May 6th, 2013 at 13:47

    1. Robert Nyman [Editor]

      With Firefox OS, nothing has been announced yet. But you have Firefox available on Android tablets.

      May 6th, 2013 at 23:26

  11. zakir

    Dose Firefox OS support dual sim or is Firefox OS going to support dual sim soon. wants to lauch phones running Firefox OS because of the openess it has but they want dual sim support it dose’nt have that.

    They said they will wait and see how well Firefox OS dose before they Lauch it. For now there are sticking to Android.

    May 8th, 2013 at 05:23

    1. Robert Nyman [Editor]

      I don’t know about the state there, but I believe Dual SIM aren’t on top of the list of things to support right now.

      May 8th, 2013 at 07:15

  12. Zakir

    I thought Firefox OS aim was to help low end countries own there first smartphone but the problemis what if they want a smartphone Firefox OS is looking like a good buy for them but they dont wanna buy another phone to keep there other sim you see one for business and the other for social they would rather keep one smartphone.

    it should be Firefox OS top of the list of things to support. inkow bare people who want this option rather then buying another mobile

    May 8th, 2013 at 11:21

    1. Robert Nyman [Editor]

      I’m sure this need, weighed and evaluated with other needs, is being taken into consideration by the business teams. Thanks for the feedback.

      May 9th, 2013 at 03:59

  13. Maikon

    I am trying to run the addon 3.0 on firefox/ubuntu and i missed the option in firefox menu. I am not a developer i am just a firefox fan that is curious about the os. There is a way that i can to fix it? While there is no phone for sale, i am killing my curiosity with it. rs

    May 9th, 2013 at 08:57

    1. Myk Melez

      If the option isn’t in the menu, then the addon failed to load for some reason. You might try the latest preview build to see if it fixes the problem:

      * Windows:
      * Mac:
      * Linux:

      May 17th, 2013 at 10:43

      1. Maikon

        Hi Myk,

        Unfortunately didn’t work, but thank you for your tip. Anyway i am waiting to buy the phone. It just gonna make me more excited. Thank you again.

        May 21st, 2013 at 22:37

        1. L.Helen

          Make sure you are not running Firefox in “private” mode by default, as it won’t show the Developper>Simulator menu in this case.

          May 31st, 2013 at 11:43

  14. Alex

    Downloaded latest Firefox OS simulator 3.0
    FF ver 20.0.1

    Simulator works well except whichever way I go in to Contacts, I just get a blank screen – any ideas?

    May 11th, 2013 at 14:40

    1. Myk Melez

      This sounds like issue 400 <>.

      May 17th, 2013 at 10:41

  15. vikram

    Does gwt work with this IDE?

    May 15th, 2013 at 13:59

  16. Adesh Shukla

    Which version of firefox browser is needed to install th simulator ?

    May 16th, 2013 at 07:57

    1. Robert Nyman [Editor]

      Firefox 19 and later:

      May 16th, 2013 at 08:36

  17. Robert Nyman [Editor]

    This is not an IDE, it’s a simulator for Firefox OS. You do not code etc in this.
    It can run code from any web server, so if you want to use GWT on your server you can.

    May 16th, 2013 at 08:29

  18. Adesh

    I am not able to apply for submitting app idea on the link provided on

    Please help. It says you dont have permission to access this item at Google drive

    May 17th, 2013 at 20:51

    1. Robert Nyman [Editor]

      As it says in the page you are referring to, the submission is now closed. Currently we don’t take any more proposals.

      May 18th, 2013 at 05:16

  19. aksshay

    Hi, I just downloaded and started work on it. After developing the simple application , i am not able to load into the simulator.

    => after adding the directory , i clicked on run and nothing happened.
    => when i clicked on apps->refresh
    => Got following error.

    App not updated ( Not found)

    I am running windows 8 as my OS.

    Kindly help.


    May 19th, 2013 at 04:02

    1. Robert Nyman [Editor]


      Please file a bug, as described in the post, and we’ll do what we can to help.

      May 19th, 2013 at 05:12

      1. aksshay

        Sorry, i got the answer, i changed the filename app.webapp to manifest.webapp and it worked like charm. Thanks :-)

        May 19th, 2013 at 06:32

        1. Robert Nyman [Editor]

          Ah, I see. Glad it worked out!

          May 21st, 2013 at 01:51

  20. st0rmt4il

    Great for testing new apps and own new or existed projects!.. Now to programming for FirefoxOS :D


    May 20th, 2013 at 13:07

  21. Enrico

    Hello! :)
    First of all, sorry for my bad english…
    I’m using firefox os simulator and it is really useful for testing apps (Sometimes it is better than an actual device), but now I’m stuck in developing my simple application because I’m not able to test it in any way… I hope you can answer my questions…
    1) Is there any way to simulate an SD Card using the simulator? I’d like to try devicestorage API (from sdcard) and I don’t know in which way i can test this with the simulator…
    2) Is there any way to test this API on an Unagi device, since it requires privileged permissions? The only way to test a privileged app is to send it to Firefox Marketplace?

    Thanks very much for the answer, I hope you can help me!

    May 24th, 2013 at 14:47

    1. Robert Nyman [Editor]

      Thanks, glad you like the Simulator!

      1. At this tine, unfortunately not.
      2. In the Firefox OS Simulator Dashboard you can test privileged apps by adding type: privileged to your manifest file and then just use Add Directory to add your app – that will automatically install it as a packaged app.

      May 24th, 2013 at 15:12

      1. Enrico

        Thank you for your answer!
        Since with the simulator i cannot test device-storage:sdcard, is there a way to test a privileged app also on a device?
        Except for the sdcard access, my app works fine with the simulator (that correctly recognize the app as a privileged one), but if i try pushing it to the device, nothing works (javascript disabled!) until I remove type: privileged from my manifest file… I heard that in older firmware versions there was a “Developer mode”, but it seems it has been disabled in newer versions…

        May 26th, 2013 at 05:39

        1. Robert Nyman [Editor]

          JavaScript shouldn’t be disabled when the app is pushed with type: privileged to the device, but there could potentially be a problem having it work (Developer Mode is gone, at this moment).

          Please file a bug about the functionality of an app when pushed from the Simulator and privileged access.

          May 27th, 2013 at 02:53

          1. Enrico

            I found that the problem was related to CSP restricions, it wasn’t related to the simulator! I didn’t know that these restrictions are automatically applied to privileged apps (But just on the device, not on the simulator)…
            Now i solved inserting events and scripts in separate .js files, but I still have a problem with external content…
            I’d like to have access to Google Maps APIs from my app, but this requires a script to be loaded outside of app package ( Something like ‘script type=”text/javascript” src=”h**p://…..”‘). Because of CSP restrictions in privileged apps, this works just with the simulator, but on my device I cannot load these APIs.
            Is there any way to disable CSP restrictions (for test purposes only) or any walk around for this problem? I tried this tag:

            iframe src=”frame.html” sandbox=”allow-same-origin allow-scripts”,

            But neither frame.html is able to load these scripts…

            May 28th, 2013 at 02:59

  22. Robert Nyman [Editor]

    Glad to know that you found out that CSP was the problem – I assume that means that all your local scripts/API access works now (but not the remote ones)?

    There’s no way of disabling CSP restrictions. This is our current default CSP policy.

    May 29th, 2013 at 00:24

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