Accept-Charset - HTTP 编辑

The Accept-Charset request HTTP header advertises which character encodings the client understands. Using content negotiation, the server selects one of the encodings, uses it, and informs the client of its choice within the Content-Type response header, usually in a charset= parameter. Browsers usually don't send this header, as the default value for each resource is usually correct and transmitting it would allow fingerprinting.

If the server cannot serve any character encoding from this request header, it can theoretically send back a 406 Not Acceptable error code. But for a better user experience, this is rarely done and the Accept-Charset header is ignored.

In early versions of HTTP/1.1, a default character encoding was defined: ISO-8859-1. This is no longer recommended, and now each content-type may have its own default.

UTF-8 is now well-supported and the overwhelmingly preferred character encoding. To guarantee better privacy through less configuration-based entropy, all browsers omit the Accept-Charset header: Internet Explorer 8+, Safari 5+, Opera 11+, Firefox 10+ and Chrome 27+ no longer send it.

Syntax

Accept-Charset: <charset>

// Multiple types, weighted with the quality value syntax:
Accept-Charset: utf-8, iso-8859-1;q=0.5

Directives

<charset>

A character encoding name, like utf-8 or iso-8859-15.

*

Any charset not mentioned elsewhere in the header; * is used as a wildcard.

;q=<weight>

Any encoding is placed in an order of preference, expressed using a relative quality value called the weight.

Examples

Accept-Charset: iso-8859-1

Accept-Charset: utf-8, iso-8859-1;q=0.5

Accept-Charset: utf-8, iso-8859-1;q=0.5, *;q=0.1

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• HTTP content negotiation
• Accept-Charset is no more
• Header with the result of the content negotiation: Content-Type
• Other similar headers: TE, Accept-Encoding, Accept-Language, Accept