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Applications panel - Set how Firefox handles different types of files

This article describes the settings that are available in the Applications panel of the Firefox OptionsPreferences window.

The Applications panel allows you to choose how Firefox handles different types of files. For each content type Firefox recognizes, you may select an action that Firefox will use to handle that type of content. You can view the file content in the Firefox window with Firefox for natively supported formats (Podcast, Web Feed, PDF)) or with a plugin, open the file with an application installed on your computer (or in some cases, with a web application), or you can save the file to your downloads folder.

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Applications panel 38

To change how Firefox handles a file type in the list, click on its name to select it. Open the drop-down menu to select the download action you want Firefox to use:

  • Preview in Firefox: Select it if you want Firefox to display the content. It's only applicable to a limited number of types, those that Firefox is able to decode such as Podcast, Video Podcast, Web Feed, and PDF.
Note: A particular configuration of the server hosting a PDF document could force the download of the file (disabling the preview).
  • Choose a feature or plugin: If you want a feature or a plugin in Firefox to handle the type, and one is available, select it from the drop-down menu.
  • Choose an application: To choose a local or web application to handle a type, select the application from the drop-down menu. If you want a local application that is not in the menu to handle the type, select Use other… from the drop-down menu and point Firefox to its location.
  • Save on your computer: Some file types can be saved to your computer. Select Save File from the menu for one of these file types to have Firefox save that type of file to the location specified in the Downloads settings.

Some file formats may have multiple content types, also called Internet media types, (for instance, audio/wav and audio/x-wav for Wave Sound) that you will need to change. Also, when a plugin is available to handle a content type and you choose a different action for that type, Firefox will only take your chosen action when you access the type directly. For example, you may choose to open these files with a media player application instead of using the plugin that is set to open it. In such cases, your chosen application will be used for file downloads but, when the content type is embedded inside a web page, Firefox will continue to use the plugin to handle the content type.

Note: Some file formats, such as MP3, are handled by the browser and the download action cannot be changed. For more information about natively supported audio and video formats in Firefox, see HTML5 audio and video in Firefox.

Adding, removing, or editing a download action

The Applications panel has limited functionality for editing. You can change the action for an existing file type but you cannot add or remove file types. Entries are added automatically when you download files and select actions for them. See Adding download actions.

Note: You may get problems if you download a file that is labeled with the wrong Internet media type. There is no way to identify or delete a bad entry in the list. If this happens you may need to look at the file mimeTypes.rdf in your Firefox profile folder. Deleting the mimeTypes.rdf will reset all download actions to the default settings.
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Version History
Revision #:
3 of 3
Last update:
3 weeks ago
Updated by:

See /forums/knowledge-base-articles/705127 for related discussions about this article.

1. Firefox now includes a built-in PDF viewer - see View PDF files in Firefox and How to disable the built-in PDF viewer and use another viewer - so an updated image is needed.

2. Starting in Firefox 21 on Windows 7, MP3 handling is now built-in with no way to change the download action in the Applications panel (unless you go to about:config and toggle the preference to false). The following is copied from /forums/contributors/709209?last=52569&page=2#post-52569

Firefox 21 on Windows (apparently Win 7 and above) now uses a built- in player for downloaded MP3 files. This MozillaZine thread includes a screenshot. *

Bug 799315 - Windows Media Foundation backend for media playback has the background for this new feature.

Firefox Options -> Applications settings for MP3 content types are ignored (see /questions/959542) unless you go to about:config and toggle the preference to false.

Bug 861090 - Disabling auto mp3-playback (unconfirmed) was filed on this.

P.S. This new feature also affects MP4 files. See Bug 877059 - MP3 and MP4 extension mime settings are ignored.

Test MP4 file (from "MPEG-4 format" link). The video plays in the built-in Firefox player now, but it opens in QuickTime with to false.

*The built-in player looks to be the same one used for ogg and webm files (update HTML5 audio and video in Firefox?)

Related discussion:

See also

To avoid patent issues, support for MPEG 4, H.264, MP3 and AAC is not built directly into Firefox. Instead it relies on support from the OS or hardware. Firefox supports these formats on the following platforms:
Platform 	Firefox version
Windows 7+ 	21.0
Windows Vista 	22.0
Android 	20.0
Firefox OS 	15.0

I'm having trouble wording the note on natively supported file formats . My last attempt:

{note}Note: Some file formats{for win7,win8,fx21}, such as MP3,{/for} are handled by the browser and the download action cannot be changed. For more information about natively supported audio and video formats in Firefox, see HTML5 audio and video in Firefox.{/note}

Here's the first version of this note, scoobidiver's Jul 7, 2013 revison:

{note}Note: The Internet media types that are handled by the browser{for win7,win8,fx21}, such as MP3, AAC and MP4,{/for} are enabled by default for all supported media types and cannot be reconfigured. For more info on natively supported audio and video formats, see HTML5 audio and video in Firefox.{/note}

I removed AAC and MP4 from the note to avoid confusion and because MP3 is the common case. Since Fx21 on Win7 and above, the chosen action for affected files (e.g., MP3) has no effect and Firefox automatically opens the file (unless a preference is changed in about:config - see for details).

For WinXP, Linux and Mac OS, the note doesn't give any example. It's possible that certain .wav files are an issue but the wav files I've tested (see for some links) aren't handled by Firefox but require a "helper" application or plugin. The main issue for those users is that there isn't normally an entry for OGG or WebM open media in the Applications list, since Firefox handles those formats internally.

Does anyone have another suggestion for this note?

P.S. For the background, see the discussions here and here. See also

This article used to be named "Options window - Applications panel" and is linked from the Firefox Applications Panel's "Help" button. This article is now named "Set how Firefox handles different types of files" and the in-product Applications Panel -> Help link results in a redirect.

The current title is too close to Change what Firefox does when you click on or download a file and I mix them up all the time. I propose renaming tis article to the following:

Applications panel - Set how Firefox handles different types of files

If I do that, will I have to update the current redirect or will that happen automatically? See

I just came across this thread while reviewing a revision. I think that's a good new name for the article. The redirect should happen automatically. Thanks!

Jon, I renamed this article just now, from "Set how Firefox handles different types of files" to "Applications panel - Set how Firefox handles different types of files". I also adjusted the slug, to applications-panel-set-how-firefox-handles-files (otherwise it would have ended in the middle of a word).

The in-product Help link in the Applications panel redirects automatically, just like you said it would.