What is MIME type "text/x-opml"?

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

text/x-opml is a MIME type for files using the Outline Processor Markup Language (OPML) 2.0. It formats outlines and hierarchies using plain text with XML structure.

This type is common in applications that exchange structured lists. It lets programs import/export data like RSS feed subscriptions and organized tasks.

The main use is exchanging outline data between different applications.
It is used in news aggregators for managing RSS feeds.
It supports mind mapping and project planning by maintaining a clear hierarchy.

Files in this format are stored as XML, making them both human-readable and easy for machines to process. They are usually seen with the OPML extension.

For more technical details, check out the OPML entry on Wikipedia.

Associated file extensions

.opml

Usage Examples

HTTP Header

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


    Content-Type: text/x-opml

HTML

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


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

Associated file extensions

.opml

FAQs

What is the primary purpose of the text/x-opml MIME type?

The text/x-opml MIME type is used to identify files written in the Outline Processor Markup Language (OPML). It is most commonly used by news aggregators and RSS readers to import and export lists of subscription feeds in a single opml file.

How do I configure Apache to serve OPML files correctly?

To ensure your Apache server sends the correct header for OPML files, add the following line to your .htaccess file or server configuration: AddType text/x-opml .opml. This ensures browsers and RSS clients recognize the file type immediately.

Can I use text/xml instead of text/x-opml?

Yes, since OPML is based on XML, generic MIME types like text/xml or application/xml are frequently used and valid. However, using text/x-opml is more specific and helps client applications distinguish an outline file from other generic XML data.

How do I open a file with the text/x-opml content type?

Files served as text/x-opml are typically designed to be imported into RSS readers (like Feedly or Thunderbird) or outline processors. Because the underlying format is plain text XML, you can also view and edit the source code using any standard text editor, such as Notepad++ or VS Code.

Why does my browser display a code tree when I click an OPML link?

Most modern web browsers do not have a built-in viewer for OPML outlines, so they default to rendering the raw XML tree structure. To view the outline as intended, you usually need to save the file and open it in a dedicated RSS reader or mind-mapping tool.

What does the 'x-' prefix mean in text/x-opml?

The x- prefix indicates that this is a non-standard or experimental MIME type that has not been formally registered with the IANA, although it is widely accepted by the community. While there is no official IANA registration for OPML, text/x-opml is the de facto standard used by developers.

How do I set up Nginx to handle text/x-opml?

For Nginx servers, you should modify your mime.types file or add a types block within your server configuration. Use the following syntax: types { text/x-opml opml; } to associate the extension with the MIME type.

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.