What is MIME type "application/x-java-jnlp-file"?

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

The MIME type application/x-java-jnlp-file marks a file that follows the Java Network Launching Protocol. It tells your system that the file should be processed using Java Web Start.

A JNLP file is an XML document. It provides instructions for launching a Java application from a remote server.

It specifies the locations of required Java libraries.
It configures settings and parameters for the application.
It supports secure and streamlined network delivery of Java apps.

The file works only if a compatible Java runtime is installed. It is central to Java Web Start, which downloads and runs Java applications without a traditional installer installation.

More details are available on the Oracle Java Web Start page.

Associated file extensions

.jnlp

Usage Examples

HTTP Header

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


    Content-Type: application/x-java-jnlp-file

HTML

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


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

Associated file extensions

.jnlp

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.