What is MIME type "application/vnd.font-fontforge-sfd"?

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

application/vnd.font-fontforge-sfd is a MIME type for a specialized font file format. It stores data in a Spline Font Database structure that details a font’s design.

This text-based format is used mainly by the font editor FontForge.
It contains information on vector outlines, curves, metrics, and metadata. These files help font developers edit and control every aspect of a typeface.

Used in designing and editing fonts with precision.
Assists in converting fonts to other standard formats.
Supports manual modifications and version control.
Offers a clear structure for debugging and collaboration.

The file is usually saved with the SFD extension.
For more technical details, check out resources on FontForge.

Associated file extensions

.sfd

Usage Examples

HTTP Header

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


    Content-Type: application/vnd.font-fontforge-sfd

HTML

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


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

Associated file extensions

.sfd

FAQs

How do I open a file with the application/vnd.font-fontforge-sfd MIME type?

You need to use FontForge, the open-source font editor for which this format was created. Since SFD files are project files containing vector splines and metadata, they are not intended to be opened by standard font viewers or installed directly into an operating system like Windows or macOS.

Can I use SFD files in CSS @font-face for websites?

No, web browsers do not support rendering application/vnd.font-fontforge-sfd files directly. To use the font on a website, you must export the project from FontForge to a web-compatible format like WOFF2 or WOFF.

How do I configure Apache to serve SFD files correctly?

To ensure your server sends the correct headers for download, add the following line to your .htaccess file or httpd.conf: AddType application/vnd.font-fontforge-sfd .sfd. This helps the client identify the file as a FontForge project rather than generic text.

Why is the SFD format text-based rather than binary?

The Spline Font Database is text-based to support easy version control and debugging. Because the data is readable ASCII, font developers can track changes using systems like Git, which is difficult to do with binary formats like application/font-sfnt (TTF/OTF).

What is the difference between an SFD file and a TTF file?

An SFD file is the source code of the font, containing cubic or quadratic splines, guidelines, and editor-specific data. A TTF (TrueType Font) is the compiled binary output intended for end-user installation and display.

I see a 'parse error' when opening an SFD file. What does this mean?

This usually indicates the file is corrupted or was saved with a newer version of FontForge than you are currently using. Since the format is text-based, advanced users can sometimes open the file in a text editor to inspect the lines causing the error.

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.