What is MIME type "application/x-maff"?

A MIME type is a string that tells browsers and other tools how to handle a particular kind of file.

application/x-maff is a MIME type used by the Mozilla Archive Format for archiving web pages and browser sessions.

It bundles all the resources from a web page—HTML, images, styles, and metadata—into a single container file. This makes it easier to save and later view a complete web snapshot offline.

Files using this MIME type are typically packaged as either a ZIP container or a standalone MAFF file. The container approach helps maintain the page’s original structure and links between components.

Archive complete web pages: Capture every file and asset in one go.
Preserve metadata: Keep the original formatting, links, and embedded data intact.
Offline browsing: View saved pages without needing an internet connection.
Mozilla tool integration: Works best with Firefox and Mozilla extensions designed for web archiving.

The x- prefix indicates it is not an officially registered MIME type. This means it was developed for more specific or experimental use, usually within Mozilla’s ecosystem. For more details on MIME types and their technical aspects, visit this reference.

Associated file extensions

.zip, .maff

Usage Examples

HTTP Header

When serving content with this MIME type, set the Content-Type header:


    Content-Type: application/x-maff

HTML

In HTML, you can specify the MIME type in various elements:


    <a href="file.dat" type="application/x-maff">Download file</a>

Server-side (Node.js)

Setting the Content-Type header in Node.js:


    const http = require('http');    
    
    http.createServer((req, res) => {    
      res.setHeader('Content-Type', 'application/x-maff');    
      res.end('Content here');    
    }).listen(3000);

Associated file extensions

.zip, .maff

FAQs

How do I open a MAFF file if my browser doesn't support it?

Since modern browsers have dropped native support for application/x-maff, the easiest way to open these files is to rename the file extension from .maff to .zip. You can then extract the contents using any standard archive tool and open the internal index.html file in your preferred browser.

Which web servers support the application/x-maff MIME type?

Most web servers do not have this MIME type enabled by default. To serve these files correctly on Apache, add AddType application/x-maff .maff to your configuration or .htaccess file. For Nginx, add application/x-maff maff; inside your mime.types file or types block.

Is application/x-maff supported in Google Chrome or Microsoft Edge?

No, Chrome and Edge do not natively support the Mozilla Archive Format. These browsers typically use the MHTML format (multipart/related) for saving web pages. To view a MAFF file in Chrome, you must first unzip it or use a third-party file conversion tool.

What is the relationship between MAFF and ZIP files?

A file with the MIME type application/x-maff is essentially a standard ZIP container. It holds the HTML, CSS, images, and other assets of a webpage compressed into one file. This is why you can often treat them exactly like ZIP files for extraction purposes.

What is the difference between MAFF and MHTML?

While both formats archive complete webpages, MAFF uses ZIP compression, resulting in smaller file sizes. MHTML allows the browser to read the file as a single text stream without extraction but is often larger. MAFF was specific to Firefox, while MHTML is the standard for Chromium-based browsers.

Are there security risks associated with application/x-maff?

Yes, like any archive format containing web scripts (JavaScript), a application/x-maff file can theoretically contain malicious code. Always ensure you trust the source of the archive before extracting it or opening the contained HTML files in your browser.

General FAQ

What is a MIME type?

A MIME (Multipurpose Internet Mail Extensions) type is a standard that indicates the nature and format of a document, file, or assortment of bytes. MIME types are defined and standardized in IETF's RFC 6838.

MIME types are important because they help browsers and servers understand how to process a file. When a browser receives a file from a server, it uses the MIME type to determine how to display or handle the content, whether it's an image to display, a PDF to open in a viewer, or a video to play.

MIME types consist of a type and a subtype, separated by a slash (e.g., text/html, image/jpeg, application/pdf). Some MIME types also include optional parameters.

How do I find the MIME type for a file?

You can check the file extension or use a file identification tool such as file --mime-type on the command line. Many programming languages also provide libraries to detect MIME types.

Why are multiple MIME types listed for one extension?

Different applications and historical conventions may use alternative MIME identifiers for the same kind of file. Showing them all helps ensure compatibility across systems.