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Accept-Language Header Parser / Builder

Network

Build an Accept-Language request-header value from locale/quality pairs, sorted by preference, or parse an existing header into its ranked locale/quality entries

Add locales with an optional preference weight and get back a ready-to-send Accept-Language header, sorted by descending quality per RFC 9110 with the default weight of 1 omitted from the output the way real browsers write it. Paste an existing Accept-Language value into the parser instead to see exactly how a client's language preferences will be ranked, useful when debugging why a localization or content-negotiation layer picked the wrong locale for a request.

accept-languagehttpheadersi18nlocalecontent-negotiation

How to use Accept-Language Header Parser / Builder

  • 1.Add one or more locales, optionally giving each a quality weight from 0 to 1 (leave blank for the default of 1).
  • 2.Copy the generated Accept-Language header value, already sorted by descending preference.
  • 3.Paste an existing Accept-Language header into the parser field to see its ranked locale/quality breakdown instead.

Frequently asked questions

Why is the q value missing from the first locale in the output?
A quality of 1 is the default per RFC 9110, so real Accept-Language headers omit `;q=1` for it. This tool follows the same convention rather than writing it out.
Does this tool validate that a locale is a real IANA language tag?
No, it accepts any non-empty string as a language range, matching how permissive real HTTP clients and servers are. It only validates the quality value's numeric range.
How are ties in quality broken when sorting?
Locales with equal quality keep their original relative order (a stable sort), so re-ordering your input list changes the tie-break order of equal-weight entries.
Does this make a network request?
No, it only builds or parses the header value locally. It doesn't check what your actual server or browser sends.

Use via API, SDK, or MCP

cURL# Free: 1,000 req/day · Pro: 10,000 req/day
curl -X POST https://api.utilix.tech/v1/tools/accept-language-parser \
  -H "Authorization: Bearer utx_live_..." \
  -H "Content-Type: application/json" \
  -d '{"locales":[{"locale":"en-US"},{"locale":"fr","quality":0.7}],"header":"en-US,en;q=0.9,fr;q=0.8"}'

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