Support for reading and writing MAFF archives was provided in the Mozilla Application Suite, Firefox, and SeaMonkey thanks to the Mozilla Archive Format add-on from 2004 to 2018. While the original add-on is no longer maintained, the file format specification is still available and can be referenced by third-party software to provide better interoperability.
MAFF files can be opened using any ZIP extraction utility, and most operating systems can recognize them natively after changing the file extension from .maff to .zip. The original Mozilla Archive Format add-on also provided a procedure to convert between MAFF and other file formats.
Store web content in a single file
The various files required to view a saved page as it appeared on-line are saved together, and cannot be separated by accident.
Store multiple independent pages in the same archive
For example, all the open tabs can be saved in a single file.
Based on the ordinary ZIP / JAR format
The ZIP format is supported natively on many modern operating systems. The contents of MAFF archives can be accessed using any ZIP extraction utility. The support files that are saved along with the main web page can be easily separated and inspected, in their original form, while preserving the advantages of storing the related content in a single archive.
Web pages in MAFF files are compressed, not encoded, with the result of the archive being often much smaller than the original web content.
Suited for video and audio files
Compression can be used selectively for text files but not for already compressed content. This allows most multimedia formats to be opened without uncompressing the entire file first. For example, this enables seeking instantly to the middle of a video, either stored locally or remotely available through a streaming source.
View using the jar: protocol
Even without add-ons, browsers based on Mozilla technology are able to display the contents of MAFF archives natively, using the jar: protocol.
Store metadata about the saved resources
MAFF archives contain metadata like the original location from which the page was saved, as well as the date and time of the save operation. The presence of this additional data is indifferent to ordinary ZIP extractors, but may allow the browser to perform operations like:
Store arbitrary extended metadata
Archives may include the browser's scroll position in the page, text zoom level, and more.
More information about the MAFF file format can be found in the MAFF specification.