What is MIME type "text/x-comma-separated-values"?

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

text/x-comma-separated-values is a MIME type for plain text files that store tabular data. In these files, values are separated by commas, and each line typically represents one record.
Files of this type are most often opened by spreadsheet software, but text editors and database programs can also process them. They offer a simple and flexible way to exchange structured data between different applications.

Used for data exchange between different software programs
Imported and exported by spreadsheet applications
Handled by simple text editors for quick viewing or editing
Applied in basic data storage and manipulation tasks

These files are usually saved with the extension CSV. They remain popular due to their simplicity and wide support across platforms.

Associated file extensions

.csv

Usage Examples

HTTP Header

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


    Content-Type: text/x-comma-separated-values

HTML

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


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

Associated file extensions

.csv

FAQs

Is text/x-comma-separated-values the official MIME type for CSV files?

No, the official standard defined in RFC 4180 is text/csv. The type text/x-comma-separated-values is a legacy or non-standard variation often used by older browsers, operating systems, or applications before the standard was finalized.

Why does my application reject CSV uploads with this MIME type?

Strict validation logic often checks only for text/csv and rejects alternatives. To fix this, update your validation code to accept common aliases like text/x-comma-separated-values, application/vnd.ms-excel, and text/comma-separated-values for .csv files.

How do I open a file with the text/x-comma-separated-values content type?

These files are plain text and can be opened by any text editor like Notepad or TextEdit. For a structured view with columns and rows, use spreadsheet software such as Microsoft Excel, LibreOffice Calc, or upload the file to Google Sheets.

How do I configure Apache to serve this MIME type?

While it is recommended to use the standard text/csv, you can force this specific type by adding AddType text/x-comma-separated-values .csv to your .htaccess or httpd.conf file. This ensures the server sends the specific header required by legacy clients.

Are there security risks associated with text/x-comma-separated-values?

Yes, the primary risk is CSV Injection (Formula Injection). If a spreadsheet program opens a file containing cells starting with =, +, -, or @, it may execute malicious formulas. Always sanitize data before importing it into spreadsheet applications.

What is the difference between application/csv and text/x-comma-separated-values?

There is no difference in the file content; both refer to comma-separated text files. However, text/x-comma-separated-values explicitly categorizes the file as text, implying it is human-readable, whereas application/csv suggests it is meant for software processing. Both are legacy types superseded by text/csv.

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.