What is MIME type "application/x-windows-installer"?

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

application/x-windows-installer is the MIME type assigned to Windows Installer packages. It signals that the file is meant to install, update, or modify software on Microsoft Windows systems.
Files with this MIME type work with the built-in Windows Installer service to perform setup tasks automatically.

This type covers files such as MSI, MST, and MSP.
MSI files contain the main installation package.
MST files are used to customize or modify configurations during installation.
MSP files apply updates and patches to installed software.

Automated Installation: Launches seamless software installations.
Custom Configuration: Supports modifications through transform files.
Patching: Applies updates and bug fixes via patch packages.
Maintenance: Allows rollback and repair actions if installation issues occur.

The Windows Installer engine reads instructions from these files to ensure proper setup and system changes.
For more technical details, visit the Microsoft Windows Installer page.

Associated file extensions

.msi, .mst, .msp

Usage Examples

HTTP Header

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


    Content-Type: application/x-windows-installer

HTML

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


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

Associated file extensions

.msi, .mst, .msp

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.