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Content-Type

The Content-Type entity header is used to indicate the media type of the resource.

In responses, a Content-Type header tells the client what the content type of the returned content actually is. Browsers will do MIME sniffing in some cases and will not necessarily follow the value of this header; to prevent this behavior, the header X-Content-Type-Options can be set to nosniff.

In requests, (such as POST or PUT), the client tells the server what type of data is actually sent.

Header type Entity header
Forbidden header name no
CORS-safelisted response header yes
CORS-safelisted request header yes, with the additional restriction that values can't contain a CORS-unsafe request header byte: 0x00-0x1F (except 0x09 (HT)), "():<>[email protected][\]{}, and 0x7F (DEL).
It also needs to have a MIME type of its parsed value (ignoring parameters) of either application/x-www-form-urlencoded, multipart/form-data, or text/plain.

Syntax

Content-Type: text/html; charset=UTF-8
Content-Type: multipart/form-data; boundary=something

Directives

media-type
The MIME type of the resource or the data.
charset
The character encoding standard.
boundary
For multipart entities the boundary directive is required, which consists of 1 to 70 characters from a set of characters known to be very robust through email gateways, and not ending with white space. It is used to encapsulate the boundaries of the multiple parts of the message. Often, the header boundary is prepended with two dashes and the final boundary has two dashes appended at the end.

Examples

Content-Type in HTML forms

In a POST request, resulting from an HTML form submission, the Content-Type of the request is specified by the enctype attribute on the <form> element.

<form action="/" method="post" enctype="multipart/form-data">
  <input type="text" name="description" value="some text">
  <input type="file" name="myFile">
  <button type="submit">Submit</button>
</form>

The request looks something like this (less interesting headers are omitted here):

POST /foo HTTP/1.1
Content-Length: 68137
Content-Type: multipart/form-data; boundary=---------------------------974767299852498929531610575

-----------------------------974767299852498929531610575
Content-Disposition: form-data; name="description" 

some text
-----------------------------974767299852498929531610575
Content-Disposition: form-data; name="myFile"; filename="foo.txt" 
Content-Type: text/plain 

(content of the uploaded file foo.txt)
-----------------------------974767299852498929531610575--

Specifications

Specification Title
RFC 7233, section 4.1: Content-Type in multipart Hypertext Transfer Protocol (HTTP/1.1): Range Requests
RFC 7231, section 3.1.1.5: Content-Type Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
Content-Type Yes 12 Yes Yes Yes Yes
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
Content-Type Yes Yes Yes Yes Yes Yes

See also

© 2005–2020 Mozilla and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Type