What is MIME type "application/typescript"?

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

application/typescript signals that a file is written in the TypeScript language. It tells operating systems, browsers, and development tools how to process the file properly.

TypeScript is a superset of JavaScript. It comes with static types and additional language features that improve code reliability. Files with this MIME type are meant to be compiled into standard JavaScript so browsers can run them.

Files labeled with this MIME type typically have extensions such as TS, CTS, or MTS. They alert tools and servers to use the correct processing pipeline of a TypeScript compiler.

Content Handling: Servers deliver these files with proper encoding and instructions for processing.
Development Process: Build systems and compilers transform TypeScript into JavaScript.
Modern Frameworks: Frequently used in projects built with frameworks like Angular and React.

For more details on the language, visit the TypeScript official website.

Associated file extensions

.ts, .cts, .mts

Usage Examples

HTTP Header

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


    Content-Type: application/typescript

HTML

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


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

Associated file extensions

.ts, .cts, .mts

FAQs

Can web browsers execute application/typescript files directly?

No, standard web browsers cannot execute TypeScript directly. The code must be "transpiled" (compiled) into standard JavaScript (usually text/javascript) before a browser can run it. However, tools like Deno or development bundlers may process application/typescript files on the fly during the development phase.

Why does my server identify .ts files as video/mp2t instead of application/typescript?

The .ts file extension is officially registered with IANA as MPEG Transport Stream (video/mp2t), a video format. Because this registration predates TypeScript, many web servers (like Apache and IIS) default to the video MIME type. To fix this, you must manually configure your server to associate .ts with application/typescript or video/mp2t depending on the actual content.

How do I configure Nginx to serve TypeScript files correctly?

You need to update your mime.types file or add a directive inside your server block. Add the line application/typescript ts tsx; to ensure Nginx serves TS files with the correct header. This is particularly important for development servers or when serving source maps.

What is the difference between .ts, .mts, and .cts files?

While .ts is the standard extension, MTS explicitly indicates an ES Module TypeScript file, and CTS indicates a CommonJS TypeScript file. The application/typescript MIME type applies to all three, but the specific extension tells the Node.js runtime and TypeScript compiler how to handle module imports and exports.

Why do I get a "Refused to execute script" error with TypeScript files?

This error occurs if you reference a .ts file in a <script> tag and the server sends it with a non-executable MIME type (like video/mp2t) or if the browser strictly enforces MIME types via X-Content-Type-Options: nosniff. Since browsers expect JavaScript, you should generally link to the compiled .js file instead of the raw TypeScript source.

Should I use application/typescript or application/x-typescript?

Both are commonly used, but application/typescript is the modern convention. The x- prefix implies a non-standard or experimental type (application/x-typescript), which was common before TypeScript gained widespread adoption. Most modern build tools recognize both, but consistency is key within your project configuration.

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.