Applications panel - Set how Firefox handles different types of files

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Note: This article applies to Firefox version 55 and below. For Firefox 56 and above, see the article Change what Firefox does when you click on or download a file.

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

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.

Applications panel 38

Change the action for a file type

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.

Add or remove a file type

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.

If you are having problems or if you just want to start fresh, you can reset all download actions to the default settings. Open your Firefox profile folder, delete (or rename) the mimeTypes.rdfhandlers.json file and then restart Firefox.

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