Parse Accept-Language and Accept Headers

Parse Accept-Language and Accept headers

HTTP clients send Accept-Language to describe locale preferences and Accept to rank media types. Both use comma-separated tokens with optional q quality values from 0 to 1 (default 1). Servers should sort by descending q when choosing a representation, per RFC 9110 semantics.

Typical debugging workflow

Paste a header copied from browser devtools or curl -H output.
Confirm tokens and q-factors after sorting.
Compare against content negotiation rules in your API or CDN.

To decode JSON Web Tokens often sent beside language headers, open the JWT Decoder.

Frequently Asked Questions

What does *;q=0.1 mean?

The asterisk is a wildcard language or media range with low priority. It tells the server you prefer listed types first but will accept others with q=0.1.

Are quotes required?

Parameter values may be quoted; this parser strips surrounding quotes on q values. Token names themselves are usually unquoted language tags or MIME types.

Is my header stored?

Parsing happens locally in the browser. Headers are not uploaded for analysis.

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Accept Language Parser