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

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-object labels files that hold compiled code. They are object files produced by a compiler that contain machine instructions, relocation data, and symbols. These files are intermediate outputs and need to be linked to form a complete executable.

They are used in software builds where compiled modules are combined during the linking process. Developers rely on these files to optimize incremental builds and debug subtle issues. Common file extensions include OBJ and O.

They contain binary code segments ready for the linker.
They hold relocation information needed for addressing during the final build.
They help speed up recompilation by enabling modular builds.
They assist in isolating and debugging specific code sections.

The x- prefix indicates that this MIME type is experimental or non-standard. For more details on how object files work, visit Wikipedia’s Object File article.

Associated file extensions

.obj, .o

Usage Examples

HTTP Header

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


    Content-Type: application/x-object

HTML

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


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

Associated file extensions

.obj, .o

FAQs

What kind of data does application/x-object contain?

This MIME type represents compiled object code, which is an intermediate binary format produced by compilers (like GCC or MSVC). It contains machine instructions, symbol tables, and relocation data used by a linker to create a final executable. It is distinct from source code files.

Is application/x-object used for 3D model files?

Generally, no. While 3D Wavefront files also use the .obj extension, they are typically text-based and should use MIME types like model/obj or text/plain. The application/x-object type is specifically for binary compiled code (often associated with .o or .obj in C/C++ projects).

How do I open or view a file with this MIME type?

Because these are binary files, you cannot view them in a standard text editor. Developers use command-line tools such as objdump, nm, or readelf on Linux/Unix, or dumpbin on Windows, to inspect the headers and symbol tables.

How do I configure Apache or Nginx to serve object files?

For Apache, add AddType application/x-object .o .obj to your config or .htaccess file. For Nginx, add application/x-object o obj; inside your mime.types file or types block. This ensures browsers download the file rather than trying to display it.

What happens if a browser tries to open an application/x-object file?

Web browsers cannot execute or render binary object code. Consequently, the browser will trigger a Save As dialog, prompting the user to download the file to their local machine.

Why does the MIME type start with x-?

The x- prefix indicates that this is a non-standard or experimental type that has not been officially registered with the IANA. However, it is the de facto standard used by many systems to identify compiled object files.

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.