Accept-Charset Inspect

Run parsing, conversion, and validation in your browser. No input is sent to a server. Use it for first-pass format troubleshooting.

Status

Runs in your browser. No input is sent to a server. Use this as a first-pass diagnostic step.

How to use

Paste Accept-Charset or Request Headers and click “Parse”. It summarizes character sets and q priorities.

Notes (this tool)

  • Accepts Accept-Charset: header lines (multi-line paste is OK).
  • q=0 means “not acceptable”.

About this page

What does this tool do?

Split Accept-Charset to list accepted character sets (utf-8/shift_jis/iso-8859-1, etc.) and their q priorities.

Useful for diagnosing mojibake and encoding mismatches.

Basics (role of Accept-Charset)

  • Accept-Charset indicates which character sets the client accepts.
  • Actual response charset is indicated by Content-Type charset.
  • Modern browsers often do not send Accept-Charset.

How to read q values (priorities)

  • q=1.0 is highest priority; smaller q means lower priority.
  • q=0 means “not acceptable”.
  • If omitted, q is typically treated as 1.0.

Relation to Content-Type charset

The actual response charset is determined by the Content-Type charset.

  • For HTML, <meta charset> also matters; keep it consistent with Content-Type.
  • For APIs, UTF-8 fixed responses are generally safest.

Input examples

  • Accept-Charset: utf-8, iso-8859-1;q=0.5
  • Accept-Charset: shift_jis;q=0.8, *;q=0.1
  • Paste full Request Headers

Common pitfalls

  • Assuming Accept-Charset is sent when it is not
  • Content-Type charset does not match actual body
  • Mismatch between HTML <meta charset> and Content-Type

Debugging workflow (recommended)

  • Check Accept-Charset via Request Headers Parser
  • Summarize acceptable charsets here
  • Check Content-Type charset with Content-Type Inspect
  • Content-Type Inspect
  • Request Headers Parser
  • Response Headers Parser

What this tool does

  • Parse Accept-Charset and summarize q priorities
  • List character sets
  • Highlight related headers to verify

Operational notes

  • The same string can be interpreted differently by context. Prioritize destination specifications.
  • Watch for upstream auto-conversion such as spaces, line breaks, and URL decoding.

Referenced specs

  • RFC 9110 (HTTP Semantics)
  • RFC 2978 (HTTP Charset)
  • MDN: Accept-Charset

FAQ

Is Accept-Charset always sent?

No. Modern browsers often omit it; UTF-8 is the common default.

Where to check when mojibake occurs?

Check Content-Type charset, HTML <meta charset>, and the actual body encoding.

References

  1. RFC 9110
  2. RFC 2978
  3. MDN: Accept-Charset
  4. MDN: Content-Type

These links are generated from site_map rules in recommended diagnostic order.

  1. Content-Language Inspect — Parse Content-Language and inspect delivered locale
  2. Accept-Language Inspect — Parse Accept-Language and inspect language priority
  3. Accept Header Builder — Build Accept-family headers by use case

Language/Locale

Compare Accept headers with Content-Language to debug negotiation mismatches