La versión 3.5 (antes numerada como la versión 3.1), llamada Shiretoko, fue lanzada el 30 de junio de 2009. Es compatible con la etiqueta como define la especificación HTML 5; en el cual incluye compatibilidad nativa con los códecs libres Ogg Theora y Ogg Vorbis.

Esta versión incluye características que no pudieron ser desarrolladas a tiempo para Firefox 3. La interfaz de usuario se mejoró visualmente, se incluyó una aplicación para organizar el historial que complementará al organizador de «marcadores», se implementará el «modo privado», mediante el cual el navegador no guardará cookies, historial ni relleno de formularios, y se usa la versión 1.9.1 de Gecko, que incluye características que no fueron incluidas en la versión 1.9.

También incorpora un compilador JIT (Just in Time) y nuevo motor para la ejecución de código JavaScript, llamado TraceMonkey que ofrece mejoras de rendimiento notables en aplicaciones web con abundante uso de JavaScript, como Gmail.

La geolocalización es una característica integrada en esta versión y en su variante móvil, actualmente conocido como Fennec. Gracias a la nueva característica los usuarios podrán compartir su localización con sitios web a través de ambos navegadores.

What’s New in Firefox 3.5.5

Firefox 3.5.5 fixes the following issues:

  • Fixed several stability issues.

Please see the complete
list of changes
in this version. You may also be interested in
the Firefox 3.5.4 release
for a list of changes in the previous version.

System Requirements

Before installing, make sure your computer meets the system


Mozilla provides Firefox 3.5 for Windows, Linux, and Mac OS X in a variety of languages. You can get the latest version of Firefox 3.5 here. For builds for other systems and languages not provided by Mozilla, see the Contributed Builds section at the end of this document.


Please note that installing Firefox 3.5 will
your existing installation of Firefox.
You won’t lose any of your bookmarks or browsing history,
but some of your extensions and other add-ons might not work
until updates for them are made available. You can reinstall an
older version later if you wish to downgrade.


You can remove Firefox 3.5 through the Control Panel in the
Start Menu on Windows, by removing the Firefox application on
OS X, or by removing the firefox folder on Linux.

Removing Firefox 3.5 won’t remove your bookmarks, web browsing history,
extensions or other add-ons. This data is stored in your profile
, which is located in one of the following locations depending on
your operating system:

Windows Vista Users\<UserName>\AppData\Roaming\Mozilla\Firefox
Windows 2000, XP, Server 2003 Documents and Settings\<UserName>\Application Data\Mozilla\Firefox
Mac OS X ~/Library/Application Support/Firefox
Linux and Unix systems ~/.mozilla/firefox

Any version of Firefox that you install after removing Firefox 3.5 will
continue to use the data from this profile folder.

Extensions and Themes

Extensions installed under Firefox 3 may be incompatible and/or require updates to work with
Firefox 3.5. Please report any issues to the maintainer of the extension.
When you install Firefox 3.5 all of your Extensions and Themes will be
disabled until Firefox 3.5 determines that either a) they are compatible
with the Firefox 3.5 release or b) there are newer versions available that
are compatible.

Known Issues

This list covers some of the known problems with Firefox 3.5 which will
be fixed in future updates or releases:

All Systems
  • Restoring your bookmarks from a backup can take some time, during which the
    browser may seem unresponsive (see bug 493731)
  • Firefox 3.5 will only support color profiles as specified by ICC v2,
    later versions will add support for ICC v4 (see bug 463221)
  • Websites using the new downloadable font support that wish to change the color
    using :hover will also need to add
    text-rendering : optimizeLegibility for font sizes less
    than 20 pixels (see bug 495455)
  • Some sites with Flash can cause problems with the Cookies dialog (see bug 495035)
  • Web pages can no longer automatically install PKCS11 cryptographic
    tokens. Users are now required to do this manually or install an
    Add-on that installs them (see instructions
    and documentation
Microsoft Windows
  • If you select Fax from the Print Dialog, the Windows Fax dialog will appear
    and then disappear. Faxing still works from other applications (see bug 440486)
Mac OS X
  • If the user repeatedly changes the paper size and asks for a Print Preview,
    Firefox may crash (see bug 495567)
Linux and Unix
  • Zooming out on some sites may result in grey or black lines appearing (see
    bug 477552)


  • Poorly designed or incompatible extensions can cause problems with your browser,
    including make it crash, slow down page display, etc. If you encounter strange
    problems relating to parts of the browser no longer working, the browser not
    starting, windows with strange or distorted appearance, degraded performance, etc,
    you may be suffering from Extension or Theme trouble.
    Restart the browser in Safe Mode. On Windows, start using the “Safe Mode” shortcut created in your
    Start menu or by running firefox.exe -safe-mode. On Linux,
    start with ./firefox -safe-mode and on Mac OS X, run:

    cd /Applications/

    ./firefox-bin -safe-mode

    When started in Safe Mode all extensions are disabled and the Default theme is
    used. Disable the Extension/Theme that is causing trouble and then start normally.

  • If you uninstall an extension that is installed with your user profile (i.e.
    you installed it from a Web page) and then wish to install it for all user profiles
    using the -install-global-extension command line flag, you must restart the
    browser once to cleanse the profile extensions datasource of traces of that
    extension before installing with the switch. If you do not do this you may end
    up with a jammed entry in the Extensions list and will be unable to install
    the extension globally.
  • If you encounter strange problems relating to bookmarks, downloads, window
    placement, toolbars, history, or other settings, it is recommended that you try
    creating a new profile and attempting to reproduce the problem before filing
    bugs. Create a new profile by running Firefox with the -P command line
    argument, choose the “Manage Profiles” button and then choose “Create
    Profile…”. Migrate your settings files (Bookmarks, Saved Passwords, etc) over
    one by one, checking each time to see if the problems resurface. If you do
    find a particular profile data file is causing a problem, file a bug and attach
    the file.

Frequently Asked Questions

  1. What can I do to help?We need help from developers and the testing community to provide as much
    feedback as possible to make Firefox even better. Please read these notes and
    the bug filing instructions
    before reporting any bugs to Bugzilla. You can
    also give us your feedback through this feedback form.
  2. Where can I get extensions and themes (add-ons)?Extensions and
    Themes can be downloaded from
    Firefox Add-ons.
  3. Who makes Firefox 3.5?Lots of people. See Help->About Mozilla Firefox, Credits for a list of some of the people who
    have contributed to Firefox 3.5.
  4. Where’s the Firefox 3.5 source code?A tarball of the Firefox 3.5 source code is available for download.
    The latest development code can be obtained through Mercurial.
    Firefox-specific source is in mozilla-central’s “browser”, “toolkit”,
    and “chrome” directories. Please follow the build instructions.
  5. Where is the mail client?Firefox 3.5 works with whatever mail client is the default on your system.
    However, we recommend Mozilla Thunderbird, our
    next-generation email client and the perfect complement to Firefox.

Contributed Builds

These are unofficial builds and may be configured differently than the official
Mozilla builds. They may also be optimized and/or tested for specific
platforms. You can browse through the available contributed builds on the