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Content-Disposition

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 must be used on each 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),
Request header, Response 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 displayed 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"

Note: Chrome, and Firefox 82 and later, prioritize the HTML <a> element's download attribute over the Content-Disposition inline parameter (for same-origin URLs). Earlier Firefox versions prioritize the header and will display the content inline.

As a header for a multipart body

A multipart/form-data body requires a Content-Disposition header to provide information for each subpart of the form (e.g. for every form field and any files that are part of field data). The first directive is always form-data, and the header must also include a name parameter to identify the relevant field. Additional directives 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; 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 refers 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 stripped, 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 understood.

Warning: The string following filename should always be put into quotes; but, for compatibility reasons, many browsers try to parse unquoted names that contain spaces.

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: 21

<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 an 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
Use of the Content-Disposition Header Field in the Hypertext Transfer Protocol (HTTP)
# header.field.definition
Returning Values from Forms: multipart/form-data
# section-4.2

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
Content-Disposition
Yes
12
Yes
From version 82, if an <a> element's download attribute is set (for a same-origin URL) then the inline directive is ignored. Earlier versions did not match the specification and respected the header directive over the attribute. See bug 1658877.
Yes
Yes
Yes
Yes
Yes
Yes
From version 82, if an <a> element's download attribute is set (for a same-origin URL) then the inline directive is ignored. Earlier versions did not match the specification and respected the header directive over the attribute. See bug 1658877.
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.
  • Firefox 82 (and later) and Chrome prioritize the HTML <a> element's download attribute over the Content-Disposition inline parameter (for same-origin URLs). Earlier Firefox versions prioritize the header and will display the content inline.

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Disposition