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

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

application/x-ms-application is a MIME type used mainly in Microsoft's ClickOnce deployment technology.
It is paired with the file format APPLICATION that contains the deployment manifest.
The manifest lists instructions on how to launch and update a Windows application directly from a web link.

Main use: Deploy and run ClickOnce applications.
What it does: Carries essential configuration details like versioning, file locations, and update policies.
Advantages: Simplifies installation by automating resource downloads and update checks.

Additional details and technical examples can be found at Microsoft ClickOnce Deployment.

Associated file extensions

.application

Usage Examples

HTTP Header

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


    Content-Type: application/x-ms-application

HTML

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


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

Associated file extensions

.application

FAQs

What is the application/x-ms-application MIME type used for?

This MIME type is specifically used for Microsoft ClickOnce deployment manifests. When a web server serves a file with the extension .application using this type, it instructs the Windows operating system to launch the ClickOnce installer to download, install, or update a Windows application.

How do I configure IIS to serve .application files?

In IIS Manager, navigate to the specific site or directory, open the MIME Types feature, and click "Add...". Set the file name extension to .application and the MIME type to application/x-ms-application. Without this mapping, IIS may return a 404 error or serve the file as plain text.

Why does the .application file download as XML code instead of running?

This usually happens if the web server is not configured to send the correct application/x-ms-application header. If the browser receives the file as text/xml or text/plain, it will display the raw XML code. You must ensure your server (Apache, Nginx, or IIS) has the correct MIME mapping.

How do I add this MIME type to Apache or Nginx?

For Apache, add the line AddType application/x-ms-application .application to your .htaccess or configuration file. For Nginx, include application/x-ms-application application; inside the types { } block usually found in mime.types or nginx.conf.

Do all browsers support application/x-ms-application automatically?

No, native support is primarily found in Microsoft Edge and Internet Explorer. Browsers like Chrome and Firefox may require a ClickOnce extension or helper add-on to recognize the MIME type and trigger the installer; otherwise, they may simply download the file to the disk.

Is the application/x-ms-application file type dangerous?

Because this file type initiates the installation of software, it poses a security risk similar to .exe files. You should only open .application files from trusted sources. See more about file safety on our MIME type security page.

What is the difference between .application and .manifest files?

The .application file uses application/x-ms-application and serves as the deployment entry point to check for updates and installation status. The .manifest file typically uses application/x-ms-manifest and lists the specific dependencies and files required for a specific version of the application.

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.