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

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

application/x-xpinstall is a MIME type used to identify installation packages designed for Mozilla-based software. It tells the system that the file should be handled by an installer that manages add-ons or extensions.

Files tagged with this MIME type are usually packaged in the XPI format. These packages contain all the components needed for the installation process, much like a compressed archive with scripts, images, and metadata.


This system simplifies the process for users by handling the install automatically. It helps developers deploy enhancements without requiring manual extraction or setup. For more technical details on MIME types and how they work with installation files, visit the Mozilla Developer Network.

Associated file extensions

.xpi

Usage Examples

HTTP Header

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


    Content-Type: application/x-xpinstall
  

HTML

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


    <a href="file.dat" type="application/x-xpinstall">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-xpinstall');
      res.end('Content here');
    }).listen(3000);
  

Associated file extensions

.xpi

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.