toolbox.app
Zero Data Retention

MIME Type Reference

Extension to Content-Type.

Look up the Content-Type for a file extension, or the extensions for a type. About 150 common entries across web, images, fonts, audio, video, documents, archives, and certificates.

Zero retention: your data never leaves this browser. Verify it yourself in DevTools

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About MIME types

How Can You Verify That Nothing Leaves This Browser?

You do not have to take our word that your data stays here. Developer tools show every request a page makes, so you can watch this page work and confirm that nothing is sent. The check takes under a minute.

  1. Open your browser developer tools with F12, or Cmd+Option+I on a Mac, and select the Network tab.
  2. Reload the page and let it finish. You will see the page's own files, its web fonts, and one anonymous page-view request. Nothing has been typed yet, so none of them can contain your data.
  3. Click the clear icon in the Network tab so that the log is empty.
  4. Use the tool with your own input.
  5. Look at the Network tab again. It is still empty. For extra proof, turn on offline mode after the page loads and the tool keeps working.

Only two things can add a line to that log, and neither carries your data. Submitting the feedback form sends the vote and comment you typed. Typing characters in a script the page has not displayed yet, such as Cyrillic or Greek, can make the browser fetch the matching font file, and that request names only the font.

The production site also sends a Content-Security-Policy header that tells your browser to refuse connections to anywhere except this site and the anonymous analytics endpoint, so a coding mistake could not quietly send your data elsewhere.

What Is a MIME Type?

A MIME type, or media type, tells the receiver what kind of data it is getting, in the form type/subtype, such as text/html or image/webp. Web servers send it in the Content-Type header, and browsers decide what to do with a response from it, not from the file extension. A wrong type can make a stylesheet be ignored, a script refuse to run, or a file download instead of display.

The official list is the IANA media-type registry. Some widely used types, such as video/x-matroska, were never registered, and the table marks those.

Which Types Do Web Developers Get Wrong?

  • JavaScript is text/javascript. RFC 9239 made that official in 2022 and marked application/javascript obsolete, though both work.
  • Web app manifests are application/manifest+json.
  • WOFF2 fonts are font/woff2, and SVG is image/svg+xml.
  • WebAssembly must be application/wasm for streaming compilation to work.
  • JSON-LD is application/ld+json, the type used in structured-data script tags.

Why Does nosniff Matter?

Browsers used to guess a type from the content when the header looked wrong, a behavior called MIME sniffing, which attackers abused by uploading files that were later run as scripts. The X-Content-Type-Options: nosniff header turns sniffing off, so correct Content-Type values become essential. The 2htaccess security headers option adds it.

What Should You Use for Unknown Files?

application/octet-stream means arbitrary binary data, and browsers download it rather than display it. It is the safe default for anything you do not want rendered. Some extensions, such as .ts, are shared by different formats, TypeScript source and MPEG transport streams, so the table lists both. This reference may move to a dedicated HTTP tool later.

What Other Tools Are in the References Lane?

  • HTTP status: Every IANA-registered HTTP status code, searchable, with plain-English meanings.
  • Quick index: Know the job but not the tool? Find the right one by task.

Elsewhere in the toolbox: 2uuid, 2gitignore, 2csp, 2htaccess, and more on the 2toolbox home page. Part of the 2suite.io privacy-first ecosystem.

Frequently Asked Questions

Is it text/javascript or application/javascript?

text/javascript is the current standard under RFC 9239. Browsers accept both.

What MIME type is a .ts file?

Two things: TypeScript source, text/typescript, and an MPEG transport stream video segment, video/mp2t.

Should I add charset to Content-Type?

For text types, yes: text/html; charset=utf-8. Binary types take no charset.

Where does this list come from?

The IANA media-type registry where a type is registered, plus widely used unregistered types, which are labeled.

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