The Mozilla Archive Format (MAFF) is a legacy web archive file format that allows users to save a complete web page—including its layout, images, scripts, and media—into a single, compressed file. Primarily supported through a Firefox browser extension between 2004 and 2018, MAFF gained a dedicated following among researchers and archivists for its efficiency and fidelity.

However, as web browser architectures evolved, MAFF transitioned into an obsolete format. If you have stumbled upon a file ending in .maff, you may find that modern browsers like Chrome, Safari, or the latest versions of Firefox cannot open it natively. This article provides a comprehensive deep dive into the technology behind the Mozilla Archive Format and detailed instructions on how to access your archived data today.

What is the Mozilla Archive Format (MAFF)?

At its core, the Mozilla Archive Format is a container format based on the standard ZIP compression algorithm. Unlike the traditional method of saving a web page in a browser—which typically creates an HTML file and a separate folder containing images and CSS—MAFF consolidates every asset into one package.

The format was developed to solve the "fragmented file" problem. When you move a standard "Web Page, Complete" save, you must ensure both the file and the folder stay together. If the folder is renamed or lost, the HTML file becomes a broken skeleton of the original page. MAFF avoids this by using the ZIP structure to keep everything in an atomic unit.

Key characteristics of a MAFF file include:

  • File Extension: .maff
  • MIME Type: application/x-maff
  • Container Structure: ZIP
  • Creator: Developed primarily by Christopher Ottley and Paolo Amadini through the MAF Project.

Technical Architecture: How MAFF Works Under the Hood

The genius of MAFF lies in its simplicity. If you were to change the extension of a .maff file to .zip, you would see exactly how it is organized.

The ZIP Container

MAFF utilizes the PKWare ZIP specification. Because it uses standard compression, it is far more efficient than the MHTML (Mime HTML) format used by Internet Explorer and Chrome. MHTML relies on Base64 encoding for binary files like images, which increases the file size by approximately 33% compared to the original assets. MAFF, by contrast, often results in a file size smaller than the sum of the original parts due to the ZIP algorithm.

Internal Directory Structure

Inside a typical MAFF archive, you will find a top-level directory (often uniquely named) that contains:

  1. The Content: The original index.html or the primary document of the saved page.
  2. Associated Resources: Folders containing images, stylesheets (.css), and JavaScript files (.js).
  3. Metadata: A specialized file, usually index.rdf, which stores the context of the archive.

The Magic Bytes

Every file type has a "signature" that tells the operating system what it is. For MAFF, the magic bytes are 50 4B 03 04. This is the exact same signature used by ZIP files. This technical overlap is why manual extraction is the most reliable way to recover data from an old MAFF archive.

The Metadata Layer: Understanding index.rdf

One of the features that set MAFF apart from simple ZIP archives was its ability to store "provenance" data. When a user saved a page, the MAF extension would generate an index.rdf file using the Resource Description Framework (RDF).

This metadata file typically included:

  • Original URL: The web address where the page was located.
  • Save Date and Time: Recorded in RFC 5322 format.
  • Page Title: The title tag of the original HTML.
  • Character Set: The encoding used (e.g., UTF-8).

By storing the original URL, browsers that supported MAFF could theoretically allow users to "refresh" the page or navigate back to the live site. For historians and legal researchers, the timestamp provided a verifiable record of when a specific piece of information was present on the internet.

MAFF vs. MHTML vs. PDF: A Comparison of Archiving Methods

In the mid-2010s, users had three primary choices for saving web content. MAFF was often considered the superior choice for technical users.

MAFF vs. MHTML

MHTML (Web Archive, Single File) is the standard used by Chromium-based browsers. While it is convenient because it is natively supported, it is an uncompressed format. For pages with large high-definition images or embedded video, MHTML files become bloated. MAFF handles large media files much better because the ZIP container is designed for binary data.

MAFF vs. PDF

PDF is excellent for printing but terrible for web fidelity. When you save a page as a PDF, the fluid layout of the web is forced into rigid A4 or Letter-sized pages. Hyperlinks might break, interactive elements are lost, and the underlying HTML structure is discarded. MAFF preserves the actual code, allowing you to interact with the page as if you were still browsing it live (within the limits of the saved scripts).

MAFF vs. "Web Page, Complete"

The standard HTML + Folder method is the most compatible but the most fragile. It is prone to "link rot" within the local file system if files are moved across different operating systems with different path naming conventions. MAFF uses relative paths within the archive, making it completely portable.

The Deprecation of MAFF: Why Did It Disappear?

The decline of the Mozilla Archive Format was not due to a lack of utility, but rather a fundamental shift in how web browsers work.

The Firefox Quantum Revolution

In November 2017, Mozilla released Firefox 57, also known as "Firefox Quantum." This update replaced the old "Legacy" XPCOM and XUL-based extension system with the modern WebExtensions API.

The original MAF extension relied on deep integration with the browser's file system and UI components that were no longer available in the new API for security and performance reasons. The developers of the MAF extension found it nearly impossible to rewrite the tool within the new constraints while maintaining the same level of functionality.

Browser Evolution

Modern browsers shifted focus toward "Headless" saving and cloud-based archiving (like Evernote or Pocket). As the web became more dynamic—relying on heavy client-side rendering (React, Vue)—saving a static snapshot became increasingly difficult, regardless of the format used.

How to Open MAFF Files Today

If you have a library of .maff files, you do not need to panic. The data is not locked behind proprietary encryption. Here are three ways to access your content.

Method 1: The "Rename to ZIP" Trick (Recommended)

Since a MAFF file is essentially a ZIP archive, you can access the contents using any standard decompression tool.

  1. Locate your .maff file in your file explorer (Windows) or Finder (macOS).
  2. Right-click and select Rename.
  3. Change the extension from .maff to .zip.
  4. A warning will appear saying the file might become unusable; click Yes or Use .zip.
  5. Double-click the new ZIP file.
  6. Extract the contents. You will see a folder containing an index.html file.
  7. Open index.html in any modern browser (Chrome, Firefox, Edge).

Note: While this recovers the content, you lose the metadata-integrated viewing experience where the browser shows the original URL in the address bar.

Method 2: Using the WebScrapBook Extension

For users who still want a dedicated archiving experience, WebScrapBook is the spiritual successor to MAFF. It is available for both Firefox and Chromium browsers.

  1. Install the WebScrapBook extension from the Chrome Web Store or Firefox Add-ons gallery.
  2. Install the server-side "PyWebScrapBook" tool if you need advanced management.
  3. WebScrapBook can be configured to recognize and open legacy MAFF archives. It effectively "mounts" the archive so you can view the page with its original metadata.

Method 3: Using Browser Forks (Pale Moon or Waterfox)

If you need to view MAFF files exactly as they appeared in 2015, you can use browsers that still support legacy Firefox extensions.

  • Pale Moon: A browser that forked from Firefox years ago to maintain compatibility with "Classic" extensions. The MozArchiver extension for Pale Moon provides full MAFF support.
  • Waterfox: Another Firefox fork that focuses on user choice and privacy, which historically maintained support for older add-on architectures.

How to Convert MAFF to Modern Formats

If you want to move away from MAFF entirely for better long-term preservation, you should convert your archives to a more "future-proof" format.

Conversion to SingleFile (HTML)

The modern standard for single-file web archiving is the SingleFile extension. It produces a standard .html file where all CSS and images are embedded using Data URIs.

  • To convert, open your MAFF file using the "Rename to ZIP" method.
  • Open the index.html in your browser.
  • Use the SingleFile extension to "re-save" the page.

Conversion to PDF

If you only need the visual information for documentation and don't care about the underlying code:

  • Open the extracted index.html.
  • Use the browser's Print to PDF function.

The Future of Web Archiving: What Replaced MAFF?

While MAFF is effectively dead, the need for robust web archiving is greater than ever. The industry has moved toward two major standards:

  1. WARC (Web ARChive): This is the professional standard used by the Internet Archive (Wayback Machine). It is much more complex than MAFF, as it records the entire HTTP exchange (headers, requests, responses).
  2. SingleFile / Single-File HTML: This is the consumer standard. By embedding everything into a single HTML file via Base64, it ensures that the page can be opened by any browser on any device 50 years from now without needing special extensions or unzipping tools.

Summary

The Mozilla Archive Format was a remarkable tool that offered superior compression and metadata storage during the golden age of Firefox extensions. While its journey ended with the transition to WebExtensions, the "open" nature of the format—being based on ZIP—ensures that any data saved in .maff remains accessible to this day.

Whether you choose to manually extract your files or use modern tools like WebScrapBook, your digital history is safe. For those starting new archives today, it is recommended to use the Single-File HTML standard to ensure maximum compatibility for the future.

FAQ

Can I open MAFF files on a smartphone?

Not natively. However, because they are ZIP files, you can use a "File Manager" app on Android or the "Files" app on iOS to rename the extension to .zip, extract it, and then open the internal HTML file in a mobile browser.

Is MAFF better than MHTML?

Technically, yes. MAFF uses ZIP compression, which is more efficient for binary files (images/video) than the Base64 encoding used in MHTML. However, MHTML is more "compatible" because it is supported natively by Google Chrome and Microsoft Edge without extensions.

Why does my extracted MAFF file look broken?

This usually happens if the original page used "Absolute Paths" for its resources or relied on external scripts (like Google Fonts or CDN-hosted JavaScript) that were not included in the archive. If the external server is down or the link is broken, those elements won't load.

Is it safe to open old MAFF files?

Generally, yes. Since you are opening a local HTML file, the risks are the same as visiting a website. However, be cautious if the archived page contains old JavaScript that might attempt to run in your modern browser. If you are concerned, you can disable JavaScript in your browser before opening the file.