What is MIME type "application/x-cb7"?

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

application/x-cb7 is the MIME type for comic book archive files that use the 7-Zip compression method.
It packages sequential image files and sometimes metadata into one file so comic book readers can display the pages in order.
This format is mainly used by comic enthusiast software on PCs and mobile devices.

Digital Comic Storage: It bundles multiple image files into a single archive for efficient storage and display.
Efficient Compression: It uses 7-Zip technology to reduce file size without losing image quality.
Easy Distribution: Creators can share complete comics as one file that is simple to open with compatible readers.

The file type is used by files such as CB7 and is recognized by comic book reading applications. For more details on this format, check additional resources at Wikipedia: Comic Book Archive.

Associated file extensions

.cb7

Usage Examples

HTTP Header

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


    Content-Type: application/x-cb7

HTML

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


    <a href="file.dat" type="application/x-cb7">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-cb7');    
      res.end('Content here');    
    }).listen(3000);

Associated file extensions

.cb7

FAQs

What is the application/x-cb7 MIME type used for?

The MIME type application/x-cb7 represents Comic Book 7-Zip archives, which are typically identified by the .cb7 extension. These files act as containers holding sequential images (pages) compressed with 7-Zip technology, allowing specialized software to display them as a digital comic book.

How do I open a file sent as application/x-cb7?

You need a dedicated comic book reader such as CDisplayEx, YACReader, or MComix to view the comic properly. Since the underlying format is a standard 7-Zip archive, you can also rename the file extension from .cb7 to .7z and extract the images using 7-Zip or WinRAR.

How do I configure Apache or Nginx to serve .cb7 files?

For Apache, add the line AddType application/x-cb7 .cb7 to your .htaccess or configuration file. For Nginx, include application/x-cb7 cb7; inside the types { } block of your mime.types file to ensure the server delivers the correct header.

What is the difference between application/x-cb7, x-cbr, and x-cbz?

The difference lies in the compression method: application/x-cb7 uses 7-Zip, while application/x-cbr uses RAR and application/x-cbz uses ZIP. While .cb7 often provides higher compression (smaller file sizes), .cbz and .cbr generally have wider compatibility with older comic reading apps.

Can web browsers display application/x-cb7 files natively?

No, modern web browsers like Chrome and Firefox do not natively render comic book archives. If a server sends a file with the application/x-cb7 content type, the browser will usually trigger a download dialog rather than displaying the content.

How can I create an application/x-cb7 file?

First, compress your sequential image files (like JPEGs or PNGs) into a .7z archive using 7-Zip software. Once the archive is created, simply rename the file extension from .7z to .cb7 to make it recognizable to comic book readers.

Is application/x-cb7 an official IANA MIME type?

No, the x- prefix indicates it is a non-standard or experimental type. While not registered with IANA, application/x-cb7 is the de facto standard used by developers and comic book software to identify 7-Zip based comic archives.

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.