What is MIME type "image/x-xwindowdump"?

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

The MIME type image/x-xwindowdump identifies a raw graphics dump from an X Window System session. It captures the live display in a binary format, preserving detailed pixel data without compression.
This type is common on Unix-like systems running the X environment. It is useful when you need an exact snapshot of the screen for debugging or archival purposes.
Files produced with this MIME type are typically created by tools that generate XWD or XDM data.

Main use: Capturing the display content during an X session.
Helps developers and advanced users diagnose graphical issues.
Serves as a source file that can be converted into common image formats like PNG or JPEG.
Offers an uncompressed, exact record of a window’s pixel layout.

For more technical details on how the X Window System handles screen data, refer to the X Window System information.

Associated file extensions

.xwd, .xdm

Usage Examples

HTTP Header

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


    Content-Type: image/x-xwindowdump

HTML

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


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

Associated file extensions

.xwd, .xdm

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.