What is MIME type "application/vnd.ms-fontobject"?

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

The MIME type application/vnd.ms-fontobject is used for Embedded OpenType fonts. This format lets web pages deliver custom fonts. Browsers can download and use these fonts even if they are not installed on the user’s system.

The format is most known for websites that want a specific look for their text. Servers send this MIME type when a page requests a font. It is widely associated with older systems like Internet Explorer.

Web Design: Embedding custom fonts on pages.
Document Rendering: Ensuring text appears as intended in applications.
Legacy Support: Maintaining compatibility with older browsers.

Files using this type include the EOT format and the FNTDATA format.
For more technical details, check the IANA registration.

Associated file extensions

.eot, .fntdata

Usage Examples

HTTP Header

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


    Content-Type: application/vnd.ms-fontobject

HTML

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


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

Associated file extensions

.eot, .fntdata

FAQs

What is the application/vnd.ms-fontobject MIME type used for?

This MIME type represents Embedded OpenType (EOT) font files, a format developed by Microsoft for use on the web. It allows web servers to send custom fonts to a user's browser, specifically catering to older versions of Internet Explorer that do not support modern formats like WOFF.

Which browsers require application/vnd.ms-fontobject?

This type is primarily required by Internet Explorer 8 and earlier versions to render custom web fonts. Modern browsers (Chrome, Firefox, Safari, Edge) use WOFF or WOFF2 and generally ignore EOT files.

How do I configure Apache to serve .eot files correctly?

You should add the MIME type definition to your .htaccess file or main configuration. Use the directive: AddType application/vnd.ms-fontobject .eot. This ensures the server sends the correct header, preventing console warnings in older browsers.

How do I configure Nginx for this MIME type?

In your Nginx mime.types file, add the line application/vnd.ms-fontobject eot;. If the file is missing, Nginx might serve the font as application/octet-stream, which can cause rendering issues in strict browser environments.

Is application/vnd.ms-fontobject the same as font/eot?

No, application/vnd.ms-fontobject is the official IANA-registered MIME type for EOT files. While font/eot is sometimes seen in unofficial configurations, using the registered vnd (vendor) type is best practice for maximum compatibility with Microsoft user agents.

Why am I getting a Cross-Origin Request Blocked (CORS) error?

Browsers treat font files as distinct resources that require CORS headers if loaded from a different domain (like a CDN). You must configure your server to send Access-Control-Allow-Origin: * (or your specific domain) when serving application/vnd.ms-fontobject files.

Do I still need to include this file type in my @font-face rules?

Only if you specifically need to support Internet Explorer 8 or older. For modern web development, standardizing on WOFF and WOFF2 is usually sufficient, allowing you to drop the EOT format and its associated MIME type to save bandwidth.

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.