What is a MIME type?

A MIME type (Multipurpose Internet Mail Extensions type), also called a media type or content type, is a two-part identifier for file formats sent over the internet. It follows the format type/subtype, for example image/png or application/json.

MIME types are set in the HTTP Content-Type header and tell browsers and servers how to handle the incoming data: whether to display it, download it, or process it in a specific way.

How to use this tool

Enter a file extension (e.g. .mp4 or mp4) to find its MIME type.
Enter a MIME type (e.g. application/json) to find its file extensions.
Enter a wildcard like image/* to list all image MIME types.
Enter a keyword like audio or compressed to search descriptions.
Or click a category button to browse all MIME types in that group.

MIME type structure

Part	Example	Meaning
Type	`image`	Top-level media category
Subtype	`png`	Specific format within the category
Parameter	`charset=utf-8`	Optional extra information

Common MIME types quick reference

Extension	MIME Type	Description
.html	`text/html`	Web page
.css	`text/css`	Stylesheet
.js	`text/javascript`	JavaScript
.json	`application/json`	JSON data
.png	`image/png`	PNG image
.jpg	`image/jpeg`	JPEG image
.pdf	`application/pdf`	PDF document
.zip	`application/zip`	ZIP archive
.mp4	`video/mp4`	MP4 video
.mp3	`audio/mpeg`	MP3 audio
.woff2	`font/woff2`	Web font
.wasm	`application/wasm`	WebAssembly

HTTP Content-Type header

The Content-Type header can include an optional charset parameter for text-based types:

Content-Type: text/html; charset=utf-8
Content-Type: application/json; charset=utf-8

For binary types like images and video, charset is not applicable. JSON is always UTF-8 by RFC 8259 - including a charset parameter is redundant but harmless.

Sniffing and security

When a server sends an incorrect or missing Content-Type, some browsers attempt to MIME sniff - guessing the content type from the file's contents. This can be a security risk: a malicious file named image.png but containing HTML with scripts could be executed if the browser sniffs it as HTML.

To prevent this, servers should send the HTTP header:

X-Content-Type-Options: nosniff

This instructs the browser to always use the declared Content-Type and never sniff the content.

Vendor-specific and experimental types

application/vnd.*: vendor-specific types registered with IANA. Examples: application/vnd.ms-excel (old .xls format), application/vnd.openxmlformats-officedocument.spreadsheetml.sheet (.xlsx).
application/x-*: unofficial, unregistered experimental types. Examples: application/x-www-form-urlencoded (HTML form data), application/x-ndjson (newline-delimited JSON). Prefer registered types when they exist.