A MIME type (also called a media type or Content-Type) is a label like image/png or application/json that tells browsers and servers what kind of data a file contains so they handle it correctly.

Which MIME type should I use for JSON?

Use application/json for JSON request and response bodies. It is the registered standard type and is what most APIs and clients expect.

What is the MIME type for a PDF?

application/pdf. Setting this Content-Type tells the browser to treat the file as a PDF and open it in the built-in viewer.

What MIME type should I use for JavaScript?

text/javascript is the current standard for .js and .mjs files. The older application/javascript still works but text/javascript is now preferred by the HTML specification.

What is application/octet-stream?

It is the generic "unknown binary data" type. Servers send it to force a download when no more specific type applies, since browsers will not try to render it inline.

Is anything I look up uploaded?

No. The entire reference and search runs in your browser, so nothing you type or copy is sent anywhere.

MIME Types Reference

This is a searchable reference that maps common file extensions to the correct MIME type (Content-Type). It is for web developers and server admins who need the exact header value for a given file format.

How it works

A MIME type (media type) is a label like image/png or application/json in the form type/subtype. Servers send it in the Content-Type header so browsers and clients know how to handle the response — render it, play it, or download it. The reference lists each extension with its registered type and a short description, plus a one-click copy button. Type in the search box to filter by extension, type or description.

Example

To serve a WebP image correctly, send:

Content-Type: image/webp

Using the wrong type — for example labelling JSON as text/plain — can stop a browser or API client from parsing the response as intended.

Extension	MIME type
.json	application/json
.png	image/png
.pdf	application/pdf
.woff2	font/woff2
.mp4	video/mp4
(unknown binary)	application/octet-stream

Everything runs in your browser; nothing is uploaded.