What is MIME type "application/vnd.ms-excel.sheet.macroenabled.12"?

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

application/vnd.ms-excel.sheet.macroenabled.12 designates an Excel workbook that supports embedded macros.
This MIME type applies to spreadsheets that use the Office Open XML format. Macros—small code snippets often written in VBA—can run automated tasks within the file.
Files using this format appear as XLSM and are standard in modern versions of Microsoft Excel.

Primary use: Automating spreadsheet tasks with built-in macros.
Data management: Storing complex formulas, data analysis, and linked data sources.
Technical structure: Combines XML data with compression for efficiency.
Security note: Macros can run executable code. Enable them only from trusted sources.

For more detailed technical information, you can refer to the IANA registration or Microsoft’s official documentation.

Associated file extensions

.xlsm

Usage Examples

HTTP Header

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


    Content-Type: application/vnd.ms-excel.sheet.macroenabled.12

HTML

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


    <a href="file.dat" type="application/vnd.ms-excel.sheet.macroenabled.12">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-excel.sheet.macroenabled.12');
      res.end('Content here');
    }).listen(3000);

Associated file extensions

.xlsm

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.