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

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

application/x-mscardfile is a MIME type that tells a computer a file contains Microsoft card data. It was designed for contact information stored in a simple digital card format.

The file that uses this type is CRD. This format was common in older versions of Windows and in applications like Microsoft Cardfile.

Key fact: It holds basic contact details such as names, addresses, and phone numbers.
Key fact: The "x-" prefix means it is a non-standard or experimental type defined by Microsoft.
Use case: Opening or importing contact files in programs that support legacy Windows data.
Use case: Transitioning older contact records to modern systems.

This MIME type helps programs determine how to manage the file content. Modern systems now favor other formats like vCard, but application/x-mscardfile played an important role in early Windows-based contact management. For further technical details, see this reference.

Associated file extensions

.crd

Usage Examples

HTTP Header

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


    Content-Type: application/x-mscardfile

HTML

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


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

Associated file extensions

.crd

FAQs

What program opens files with the MIME type application/x-mscardfile?

Files with this MIME type are associated with the legacy Microsoft Cardfile application, which was included in Windows versions up to Windows 98. On modern systems like Windows 10 or 11, you cannot open them natively and may need to find a copy of the old cardfile.exe or use a third-party converter to access the data.

How do I add support for application/x-mscardfile to an Apache server?

To serve these files correctly, you should modify your .htaccess file or the main server configuration. Add the line AddType application/x-mscardfile .crd to ensure that browsers recognize the file as a binary application rather than plain text.

Is application/x-mscardfile the same as a vCard?

No, this MIME type represents an older, proprietary binary format used by Microsoft, while vCards use the standard text/vcard type. You cannot simply rename a CRD file to .vcf; the internal data structure is completely different and requires conversion.

Why does this MIME type begin with "x-"?

The x- prefix indicates that application/x-mscardfile is a non-standard or private MIME type defined by Microsoft rather than the IANA standards body. While the x- convention is deprecated in modern definitions, it remains on legacy types to maintain backward compatibility.

How do I configure Nginx to serve .crd files?

You can enable support by editing the mime.types file located in your Nginx configuration directory (usually /etc/nginx/mime.types). Add the entry application/x-mscardfile crd; to the list to ensure the server sends the correct header for these files.

Can I convert application/x-mscardfile data to Excel?

Direct conversion is difficult because the format is obsolete, but it is possible using intermediate tools. You would typically need to open the file in a legacy version of Microsoft Cardfile, print the data to a generic text file, and then import that text into Excel or a database.

What happens if a browser tries to open this MIME type directly?

Since most modern browsers do not have built-in plugins for legacy Microsoft Cardfile data, they will typically prompt the user to download the file. If the server is misconfigured and sends it as text/plain, the browser might display garbled binary characters instead.

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.