Content-Type
The Content-Type
representation header is used to indicate the original media type of the resource (prior to any content encoding applied for sending).
In responses, a Content-Type
header provides the client with the actual content type of the returned content. This header's value may be ignored, for example when browsers perform MIME sniffing; set the X-Content-Type-Options
header value to nosniff
to prevent this behavior.
In requests, (such as POST
or PUT
), the client tells the server what type of data is actually sent.
Header type | Representation 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)),
"():<>?@[\]{} , 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
http
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. Case insensitive, lowercase is preferred.
- boundary
-
For multipart entities the
boundary
directive is required. The directive consists of 1 to 70 characters from a set of characters (and not ending with white space) known to be very robust through email gateways. 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.
html
<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):
http
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 |
---|
HTTP Semantics # status.206 |
HTTP Semantics # field.content-type |
Browser compatibility
BCD tables only load in the browser
See also
Accept
Content-Disposition
206
Partial ContentX-Content-Type-Options