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

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.