Accept

The HTTP Accept request header indicates which content types, expressed as MIME types, the client is able to understand. The server uses content negotiation to select one of the proposals and informs the client of the choice with the Content-Type response header. Browsers set required values for this header based on the context of the request. For example, a browser uses different values in a request when fetching a CSS stylesheet, image, video, or a script.

Header type	Request header
Forbidden header name	No
CORS-safelisted request header	Yes*

* Values can't contain CORS-unsafe request header bytes, including "():<>?@[\]{},, Delete 0x7F, and control characters 0x00 to 0x19, except for Tab 0x09.

Syntax

http

Accept: <media-type>/<MIME_subtype>
Accept: <media-type>/*
Accept: */*

// Multiple types, weighted with the quality value syntax
Accept: text/html, application/xhtml+xml, application/xml;q=0.9, image/webp, */*;q=0.8

Directives

<media-type>/<subtype>: A single, precise media type, like text/html.
<media-type>/*: A media type without a subtype. For example, image/* corresponds to image/png, image/svg, image/gif, and other image types.
*/*: Any media type.
;q= (q-factor weighting): A value in order of preference expressed using a relative quality value called the weight.

Examples

Using default Accept request headers

HTTP requests made using command line tools such as curl and wget use */* as the default Accept value:

http

GET / HTTP/1.1
Host: example.com
User-Agent: curl/8.7.1
Accept: */*

Browser navigation typically has the following Accept request header value:

http

GET /en-US/ HTTP/2
Host: developer.mozilla.org
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
…

After receiving the document, the default Accept values in requests for images on the developer.mozilla.org example look like this:

http

Accept: image/avif,image/webp,image/png,image/svg+xml,image/*;q=0.8,*/*;q=0.5

Configuring Accept request headers for JSON responses

Systems that involve API interaction commonly request application/json responses. Here's an example of a GET request where the client specifically requests a JSON response:

http

GET /users/123 HTTP/1.1
Host: example.com
Authorization: Bearer abcd123
Accept: application/json

Specifications

Specification
HTTP Semantics # field.accept

Browser compatibility

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