What is MIME type "application/x-ms-reader"?

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-ms-reader is specific to digital book files used by the Microsoft Reader application.
It indicates that the file contains structured e-book content and tells systems how to handle it correctly, especially when opening or transferring files over the web.
Files with this MIME type are most commonly seen as LIT documents.

File association: It signals operating systems and browsers to launch the right application (Microsoft Reader) for proper viewing.
Content rendering: It supports the display of formatted text, images, and metadata, ensuring the digital book looks as intended.
Legacy support: It remains important for accessing older e-book libraries created for Microsoft Reader.

The x-ms- prefix shows that this is a vendor-specific or experimental format. For more on MIME types, check out MIME on Wikipedia.

Associated file extensions

.lit

Usage Examples

HTTP Header

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


    Content-Type: application/x-ms-reader

HTML

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


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

Associated file extensions

.lit

FAQs

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

The MIME type application/x-ms-reader is strictly associated with Microsoft Reader eBooks, which typically use the .lit file extension. It informs the operating system or browser that the file contains a digital book formatted for the now-discontinued Microsoft Reader software.

How do I configure an Apache server to serve .lit files correctly?

To ensure your Apache server sends the correct headers for Microsoft Reader files, add the following line to your .htaccess file or main configuration: AddType application/x-ms-reader .lit. This prevents browsers from misinterpreting the file as generic binary data.

How do I add support for application/x-ms-reader in Nginx?

For Nginx, you need to update your mime.types file or the http block of your nginx.conf. Add the directive application/x-ms-reader lit; to ensure clients receive the correct content type when downloading eBooks.

Can modern web browsers open application/x-ms-reader files directly?

No, modern browsers like Chrome, Firefox, and Edge do not have native support for rendering application/x-ms-reader content. Instead of displaying the book, the browser will typically force a download so the user can open the file with a local application or converter.

What software can open files with this MIME type?

Since Microsoft discontinued the official Microsoft Reader in 2012, you usually need third-party tools to view these files. The most popular solution is Calibre, which can view .lit files or convert them into modern formats like EPUB.

What does the 'x-ms-' prefix mean in this MIME type?

The x- prefix indicates that this is a non-standard or experimental type, and ms specifically identifies it as a vendor-specific format created by Microsoft. While standard types are registered with IANA, vendor types like application/x-ms-reader are defined by specific software ecosystems.

Why am I getting a 404 error when trying to download a .lit file?

If the file exists but returns a 404 or 403 error, your web server (like IIS) might not have the application/x-ms-reader MIME type allowed in its configuration. In IIS, you must explicitly add the extension .lit and its MIME type to the MIME Types feature to authorize the download.

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.