Add-on documentation

The Mozilla Archive Format add-on is an independently developed program that can be installed on the Firefox and SeaMonkey browsers to open and save MAFF and MHTML archives.

Firefox add-on technology is modernizing, and traditional add-ons like Mozilla Archive Format will stop working soon. The announced cut-off date is November 14, 2017.


This add-on uses legacy technology that will not be supported by future versions of Firefox. In order to access pages saved by this add-on, you can use one of the following alternatives:

Converting previously saved pages to other file formats

The Saved Pages Conversion Wizard automates the process of opening the web pages you stored on your computer one by one and saving them again in a different file format. While the pages saved by this process usually look like the originals, in some cases the styling might not be replicated accurately. Because of this, the procedure never deletes the original files.

Before you begin

The guided procedure can be started from the File » Convert Saved Pages menu item after installing the Mozilla Archive Format add-on.

Choosing a file format

Complete web pages (with support folders for data files)

This file format is used by default in Firefox. Web pages are stored as file / folder pairs, for example Page.html and Page_files.

This format provides the best compatibility because it can be opened in any browser without installing additional software. It can also include large video and audio files efficiently.

However, the name of the folder cannot be changed after the page is saved. The page may also become unreadable if the support folder is separated from the associated file, or if the file / folder pair is moved to a different file system where special characters, accented characters, or long file names may be lost. Backups may be significantly slower because the support folder often contains many small files.

MHTML archives

This file format was originally implemented by Microsoft Internet Explorer, and solves the issues with file / folder pairs because the entire web page is stored in a single file.

However, MHTML files use more disk space and are not suitable for saving large video and audio files. MHTML files including such content would become very slow to load.

This format provides generally good compatibility because it can be opened by Microsoft Internet Explorer and Google Chrome. On the other hand, Firefox cannot open MHTML files without installing an add-on. One compatible with future versions of Firefox does not currently exist, and additional external software would be required to open these files directly from the operating system's file manager.

MAFF archives

This file format was originally implemented by the Mozilla Archive Format add-on. MAFF files are standard ZIP files, and they can store multiple pages in a single archive.

Since these archives are compressed, they are usually smaller than the equivalent MHTML archives or file / folder pairs, and can still include large video and audio files efficiently.

However, browser support for this format is limited. While future versions of Firefox will still support the jar: protocol for reading the contents of MAFF files without installing an add-on, additional external software would be required to open these files directly from the operating system's file manager.

Selecting which files to convert

When looking for files to convert, MAFF and MHTML archives are recognized by their extension, respectively .maff and either .mht or .mhtml. Complete web pages are recognized because they have an associated support folder, for example Page.html and Page_files, but also Page (without extension) and Page_files. Web pages saved as single files, without support folders, are recognized by their extension only.

Depending on how many files are present in the source folder, building the list of files to convert may require some time. If you are working with large folder trees, you may want to repeat the procedure multiple times, converting one sub-folder at a time.

If you are using your browser in a language other than English, the recognition of additional support folder suffixes will be enabled. For example, if you are using your browser in French, a support folder named Page_fichiers is recognized, in addition to the English Page_files.

If you previously saved pages using a browser in a different language than the current one, the support folder names may not be recognized correctly, and you might have to adjust the list of recognized suffixes in the internal configuration settings.

You may want to place the converted files in a different folder from the originals if you are converting from a read-only source such as a CD-ROM or a DVD. The original folder structure is always preserved, so that if a source file is located in a sub-folder of the original folder, the converted file will be located in a sub-folder of the destination folder.

If the contents of the source folder can be modified, you can also choose to move the originals to a separate archival folder after they have been converted successfully.

The converted files will be named according to the destination format. The extension in the source file name, if present, is always replaced with the correct extension for the file type. For MHTML, the internal configuration settings determine whether the .mht or .mhtml extension is used.

You can exclude individual files from the conversion before the actual process begins. The list of files can be sorted by source file name, support folder name, and sub-folder. You can also enable additional columns to display the full paths.

If the destination file or support folder is already present, or if a file or support folder is already present in the archival folder where the source file would be moved after conversion, the source file name will appear in the list, but the selection checkbox will be disabled. This often indicates that the page was already converted successfully.

Completing the conversion

Click the Finish button to start the conversion. While the process is running, you can use the Back button or close the window to cancel.

When the operation is finished, you can see the count of how many files have been successfully converted and how many conversions failed. The icon near each file name indicates its current status: not selected, already converted, waiting for conversion, currently converting, conversion failed, or conversion succeeded. You can click the Finish button again to close the window, or use the Back button to retry the conversion with different settings.

Detailed information about the reasons for conversion failures is available in the Browser Console, accessible from the Tools » Web Developer » Browser Console menu item.

Opening web archives

After installing the Mozilla Archive Format add-on, MAFF and MHTML archives can be displayed in the browser like any other saved page. On Windows, file associations are created so that archives can be opened from the operating system's file manager.

File associations can be controlled from the welcome page that is displayed when the add-on is installed for the first time. You can display this page again using the Refresh File Associations link in the Actions pane of the add-on options.

File associations are always created explicitly for the current user of the system. In addition, if the browser is running with administration privileges, default file associations for all users are also created. File associations are not removed when uninstalling.

When you display an archived page, an information bar shows the original location from which the page was saved, as well as the date and time of the save operation. You can click the original location to open it, and use key combinations to open the link in a new tab or window.

Saving web archives

After installing the Mozilla Archive Format add-on, you can choose MAFF and MHTML as file types in the Save As dialog box. When you save in one of these formats, the following additional information is stored:

This information is also preserved if you save an already archived page to a different file. If the original file is not a web archive, the following information is still preserved:

You can save multiple tabs in an archive using the standard context menu on the tab strip or the context menu provided by the Multiple Tab Handler add-on. For MHTML archives, multiple files are created, while for MAFF archives all the tabs are saved in a single file.


When saving complete web page contents:

This option can be used to disable the integration with the Save As dialog. Normally, the integration is enabled and saved pages will always include all the images, styles, and sub-frames that are visible at the time the page is saved, including the current values of form fields. The page will be static, as scripts are disabled by the save operation.

If use browser's standard save system is selected, the integration is disabled and how much of the web page is saved depends on the version of the browser being used.

Default format when saving in a single file:

This option reflects the current file type choice in the Save As dialog.

When an archived page is opened:

This option allows disabling the information bar and the icon in the location bar that are normally displayed when viewing an archived page.

Internal configuration settings

These settings are only available from the internal configuration page of the browser, and normally don't need to be changed.


Complete web pages are recognized by the Saved Pages Conversion Wizard because they have an associated support folder, with the same base name as the main file and a different suffix, for example Page.html and Page_files.

This option contains a comma-separated list of the recognized suffixes. An additional suffix that depends on the current browser language may also be recognized without it being explicitly listed.


Controls the compression level used when saving files in a MAFF archive. This can be best to use maximum compression for all files, dynamic to avoid re-compressing media files, and none to store all the files uncompressed.


With this preference enabled, history, text zoom, and scroll position are saved for each page. This additional information is ignored when the archive is opened.


When this setting is enabled, the character set specified for pages saved inside MAFF archives is ignored. Enabling this option may be useful for troubleshooting problems with internationalization, but will cause saved pages to be displayed incorrectly in most cases.


If this preference is enabled, when you open a MAFF archive its contents will be accessed directly using the "jar:" protocol, without being extracted.

However, if you enable this option, the archive files you open will be locked, and you will be unable to move, rename or delete them until the browser is closed.


If this option is selected, and you do not type a file extension in the Save As dialog, or file extensions are hidden, the complete .mhtml extension will be appended to the file name of MHTML archives, instead of the more common .mht extension.


This option is enabled by default. If disabled, the contents of the temporary directory are preserved after the browser exits, and must be emptied manually.


Use this preference to choose the location of the temporary files required to open and save the web archives. The contents of this folder will be lost if extensions.maf.advanced.temp.clearonexit is true.

If not specified, this location defaults to a sub-folder of the system temporary folder, which is different for every browser profile.