What is MIME type "application/vnd.mozilla.xul+xml"?

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

application/vnd.mozilla.xul+xml is the MIME type for files written in XUL, which stands for XML User Interface Language.
It tells systems that the file uses XML markup to design user interfaces.
Files with this type use the XUL extension.

Primary Use: Creating dynamic user interfaces for Mozilla-based applications.
Main Functionality: It structures UI elements (windows, dialogs, and menus) using XML, similar to how HTML structures pages.
Other Uses: Building add-ons and customizing the interface of software like older versions of Firefox and Thunderbird.

Additional details and examples can be found in the Mozilla Developer Network documentation.
This MIME type ensures that the system processes the content correctly as XML-based UI instructions.

Associated file extensions

.xul

Usage Examples

HTTP Header

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


    Content-Type: application/vnd.mozilla.xul+xml

HTML

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


    <a href="file.dat" type="application/vnd.mozilla.xul+xml">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/vnd.mozilla.xul+xml');
      res.end('Content here');
    }).listen(3000);

Associated file extensions

.xul

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.