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Content-Disposition

In a regular HTTP response, the Content-Disposition response header is a header indicating if the content is expected to be displayed inline in the browser, that is, as a Web page or as part of a Web page, or as an attachment, that is downloaded and saved locally.

In a multipart/form-data body, the HTTP Content-Disposition general header is a header that can be used on the subpart of a multipart body to give information about the field it applies to. The subpart is delimited by the boundary defined in the Content-Type header. Used on the body itself, Content-Disposition has no effect.

The Content-Disposition header is defined in the larger context of MIME messages for e-mail, but only a subset of the possible parameters apply to HTTP forms and POST requests. Only the value form-data, as well as the optional directive name and filename, can be used in the HTTP context.

Header type	Response header (for the main body) General header (for a subpart of a multipart body)
Forbidden header name	no

Syntax

As a response header for the main body

The first parameter in the HTTP context is either inline (default value, indicating it can be display inside the Web page, or as the Web page) or attachment (indicating it should be downloaded; most browsers presenting a 'Save as' dialog, prefilled with the value of the filename parameters if present

Content-Disposition: inline
Content-Disposition: attachment
Content-Disposition: attachment; filename="filename.jpg"

As a header for a multipart body

The first parameter in the HTTP context is always form-data; additional parameters are case-insensitive and have arguments, that use quoted-string syntax after the '=' sign. Multiple parameters are separated by a semi-colon (';').

Content-Disposition: form-data
Content-Disposition: form-data; name="fieldName"
Content-Disposition: form-data; name="fieldName"; filename="filename.jpg"

Directives

name: Is followed by a string containing the name of the HTML field in the form that the content of this subpart refer to. When dealing with multiple files in the same field (for example, the multiple attribute of an <input type=file> element, there can be several subparts with the same name.
A name with a value of '_charset_' indicates that the part is not an HTML field, but the default charset to use for parts without explicit charset information.
filename: Is followed by a string containing the original name of the file transmitted. The filename is always optional and must not be used blindly by the application: path information should be striped, and conversion to the server file system rules should be done. This parameter provides mostly indicative information. When used in combination with Content-Disposition: attachment, it is used as the default filename for an eventual 'Save As" dialog presented to the user.
filename*: The parameters "filename" and "filename*" differ only in that "filename*" uses the encoding defined in RFC 5987. When both "filename" and "filename*" are present in a single header field value, "filename*" is preferred over "filename" when both are present and understood.

Examples

A response triggering the "Save As" dialog:

200 OK
Content-Type: text/html; charset=utf-8
Content-Disposition: attachment; filename="cool.html"
Content-Length: 22

<HTML>Save me!</HTML>

This simple HTML file will be saved as a regular download rather than displayed in the browser. Most browsers will propose to save it under the cool.html filename (by default).

An example of HTML form, posted using the multipart/form-data format that makes use of the Content-Disposition header:

POST /test.html HTTP/1.1
Host: example.org
Content-Type: multipart/form-data;boundary="boundary"

--boundary
Content-Disposition: form-data; name="field1"

value1
--boundary
Content-Disposition: form-data; name="field2"; filename="example.txt"

value2
--boundary--

Specifications

Specification	Title
RFC 7578	Returning Values from Forms: multipart/form-data
RFC 6266	Use of the Content-Disposition Header Field in the Hypertext Transfer Protocol (HTTP)
RFC 2183	Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field

Browser compatibility

Feature	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Servo
Content-Disposition	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)

Feature	Android	Chrome for Android	Edge Mobile	Firefox for Android	IE Mobile	Opera Mobile	Safari Mobile
Content-Disposition	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)

Compatibility notes

Firefox 5 handles the Content-Disposition HTTP response header more effectively if both the filename and filename* parameters are provided; it looks through all provided names, using the filename* parameter if one is available, even if a filename parameter is included first. Previously, the first matching parameter would be used, thereby preventing a more appropriate name from being used. See bug 588781.