While the Mozilla Archive Format add-on is no longer maintained, the final version released in 2018 can be installed offline on Firefox 56 to convert saved pages to other file formats. Using outdated software can result in security vulnerabilities and may corrupt user profile data, hence this procedure should only be followed by experienced users on a separate computer that is not connected to the Internet.
The guided procedure can be started from the File » Convert Saved Pages menu item after installing the Mozilla Archive Format add-on. The procedure can also be started from the options window of the add-on.
This will search the folder where pages are currently saved, looking for MAFF and MHTML files that future versions of the browser will not be able to display. The default options will be used, and the next step of the procedure will be to select which files to convert.
This allows you to follow the guided procedure in its entirety. The default options will still be preselected, but you will be able to change them as needed.
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.
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.
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.
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.
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 not included in the conversion.
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.
The conversion process will normally happen offline, because this mode is more reliable and faster. Pages saved by the Mozilla Archive Format add-on will always be converted correctly in this mode.
If you used other programs or the standard Firefox save system, some images may not have been saved, but a reference to the original file may still be present. This option will make the browser work online, and may allow the recovery of some of the referenced images from the original website.
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 cannot be modified, you can choose to leave the originals in place, instead of moving them 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 or 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.
Click the Convert 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 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.
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, MAFF files can be opened easily from the operating system's file manager, but doing the same for MHTML requires creating new file associations from the options window of the add-on.
In Firefox, saving as MAFF or MHTML is disabled by default.
This functionality can be re-enabled from the options of the add-on, keeping in mind that future versions of the browser will not be able to open the pages saved in this way. The file types will then be available in the Save As dialog box, and the MAFF format will be used by default when saving complete web pages.
The following additional information will be stored when using either format:
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.
These options are displayed on Windows only, and allow opening MAFF and MHTML archives from the operating system's file manager. These file type associations are created only for the current user of the system, and are not removed when uninstalling.
This option allows disabling the information bar that is normally displayed when viewing an archived page.
When the add-on is installed on Firefox, the ability to save pages as MAFF and MHTML is disabled by default. This option allows re-enabling this functionality, keeping in mind that future versions of the browser will not be able to open the pages saved in this way.
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.