Accept-Query header

The HTTP Accept-Query response header indicates that a resource supports the QUERY method and identifies the query format media types that it accepts. Despite its name, Accept-Query is sent by the server in a response, not by the client in a request: it tells clients what they may send as the content of a subsequent QUERY request.

Accept-Query is a structured field whose value is a list of media ranges (a media type that might include wildcards), each represented as a structured field string or token and optionally including structured field parameters. The order of media types in the list is not significant. Its value applies to every URI on the server with the same path, regardless of the URI's query component. If requests to the same resource return differing Accept-Query values, the most recently received value that is still fresh applies.

Header type	Response header

Syntax

http

// Token or equivalent quoted string
Accept-Query: <media-type>/<subtype>
Accept-Query: "<media-type>/<subtype>"

// Tokens including wildcards
Accept-Query: <media-type>/*
Accept-Query: */*

// Comma-separated list of media ranges in any order, mixing tokens and strings
Accept-Query: <media-type>/<subtype>, "<media-type-2>/<subtype-2>", <media-type-3>/*

// Media type parameters expressed as structured field parameters
Accept-Query: <media-type>/<subtype>;<parameter>=<value>
Accept-Query: <media-type>/<subtype>;<parameter>="<value>"

Note: Although its value looks similar to Accept, Accept-Query is a structured field (RFC 9651: Structured Field Values for HTTP) and must be parsed as one. In particular, it has no notion of preference via q (quality values) arguments: every media range in the list is equally acceptable, and the order of the list is not significant. This is because Accept-Query is a response header while Accept is a request header.

Directives

<media-type>/<subtype>: A media type with a subtype that the resource accepts as QUERY request content, such as application/json. Expressed as a structured field token.
"<media-type>/<subtype>": The same value expressed as a structured field string. The choice between a token and a string carries no meaning, so recipients must not treat the two forms differently. A string is required where the media range is not a valid token, such as when the type begins with a digit.
<media-type>/*: A media type that accepts any subtype. For example, image/* corresponds to image/png, image/svg, image/gif, and other image types.
*/*: Any media type.
;<parameter>=<value>: A media type parameter, such as ;charset="UTF-8", mapped to a structured field parameter on the preceding media range. Parameter values are themselves tokens or strings. The media range itself is always written without its parameters.

Examples

Advertising supported query formats

The following response indicates that the resource supports QUERY requests with application/x-www-form-urlencoded or application/sql content:

http

HTTP/1.1 200 OK
Content-Type: application/json
Accept-Query: application/x-www-form-urlencoded, application/sql

Using strings and media type parameters

Media ranges may equally be written as quoted strings, and the two forms can be mixed in one list. Here the resource accepts JSONPath queries, and SQL queries that are encoded as UTF-8:

http

HTTP/1.1 200 OK
Content-Type: application/json
Accept-Query: "application/jsonpath", application/sql;charset="UTF-8"

Because the response depends on the content of the QUERY request, a server may also send a Vary header naming the fields involved:

http

HTTP/1.1 200 OK
Content-Type: text/csv
Accept-Query: "application/sql", "application/xslt+xml"
Vary: Accept-Query, Content-Encoding, Content-Type

Specifications

Specification
Unknown specification # name-the-accept-query-header-fie

Browser compatibility

Browser compatibility is not relevant for this header. Browsers have no built-in handling of Accept-Query; it's up to the client sending QUERY requests to read the header and use it to select a supported media type for the request content.

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This page was last modified on Sep 23, 2026 by MDN contributors.

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