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

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

application/x‐ms‐compress‐sz is a MIME type for files compressed with a Microsoft method. It tells applications that the data uses a specialized compression algorithm designed for fast processing and reduced storage.
This format often appears in internal system tasks and update packages. The compression keeps data intact until software decompresses it.

A file using this type may have the extension EX$. It is not meant for everyday file handling but for system-level efficiency.

For more details on MIME types, see Mozilla Developer Network.

Associated file extensions

.ex$

Usage Examples

HTTP Header

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


    Content-Type: application/x-ms-compress-sz

HTML

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


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

Associated file extensions

.ex$

FAQs

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

The MIME type application/x-ms-compress-sz represents files compressed using a specific Microsoft algorithm, often found in Windows installation media or update packages. These files are typically compressed versions of executables or system libraries designed to save space during distribution.

How do I open a file with the .ex$ extension?

Files with the .ex$ extension are compressed and usually cannot be opened directly by clicking them. You typically need to decompress them using the Windows Command Prompt tool expand (e.g., expand filename.ex$ filename.exe) or a third-party archiver like 7-Zip.

How do I configure Apache to serve application/x-ms-compress-sz?

To ensure your Apache server correctly identifies these files, add the following line to your .htaccess file or main configuration: AddType application/x-ms-compress-sz .ex$. This ensures browsers handle the file as a binary download rather than text.

Why does my browser download the file instead of displaying it?

Browsers like Chrome, Firefox, and Edge do not have built-in support to render or execute application/x-ms-compress-sz content. Because the server identifies it as a generic or specific binary application, the browser triggers a download to save the file to your disk.

Is the application/x-ms-compress-sz format safe?

While the compression format itself is neutral, these files often contain executable code (like .exe or .dll files) once decompressed. Always scan files downloaded from the internet with antivirus software before expanding or running them.

What is the correct Nginx configuration for .ex$ files?

For Nginx servers, you can map the file extension to the MIME type in your mime.types file or inside a server block. Use the directive: types { application/x-ms-compress-sz ex$; } to ensure correct headers are sent.

Are there other extensions associated with this MIME type?

While ex$ is the primary extension associated with this specific entry, Microsoft compressed files often replace the last character of the original extension with an underscore or dollar sign (e.g., dl_, ex_). For more on the specific extension mentioned here, visit our ex$ page.

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.