Content-Type Parser (MIME, Charset, Boundary)
Parse Content-Type headers and extract MIME parameters
Paste one Content-Type value or header line per line to inspect its type, parameters, and syntax. The request body is not inspected.
The full guide also includes pitfalls, worked examples, snippets, FAQs, and related tools for checking results or troubleshooting.
About this tool
Inspect one Content-Type value or Content-Type: header line per input line. Results show the type, subtype, parameter values, and normalized text. Quoted semicolons and escaped quotes are preserved; malformed parameters and duplicate names are reported instead of silently discarded. Multipart declarations receive boundary warnings. This is local header inspection: it does not fetch a URL, read the body, verify a registered media type, or test server acceptance.
Failure Clinic (Common Pitfalls)
Normalization is not a character-encoding conversion
Cause: Lowercasing media types and parameter names or removing unnecessary quotes changes header formatting, not payload bytes.
Fix: Compare charset with the actual text encoding. For HTTP 415, also check the endpointβs accepted media types and the submitted body.
Scenario Recipes
Compare two multipart declarations
Goal: See the difference between a missing boundary and a declared boundary.
- Enter multipart/form-data on the first line.
- Enter multipart/form-data; boundary=example-boundary on the second line.
- Parse both lines. The first keeps its parsed media type and shows a missing-boundary warning.
Result: The second declares a syntactically usable boundary. You must still compare it with the delimiters in the actual body; this parser does not receive that body.
Production Snippets
Quoted parameters keep their content
text
Input: Content-Type: Text/Plain; note="a;b"; charset="UTF-8"
Normalized: text/plain; note="a;b"; charset=UTF-8
Parameters: note β a;b, charset β UTF-8Suggested Workflow
API Debugging Checklist: From Broken Response to Root Cause
A practical debugging flow for API payload errors, auth failures, and malformed responses.
Why 415 Unsupported Media Type Happens (and How to Fix It Fast)
Compare form and JSON requests for a JSON endpoint, verify the response, and distinguish browser FormData boundaries from hand-built multipart bodies.
Fix Credentialed CORS: Check Origins, Preflight and Cookies
Trace a credentialed cross-origin request through OPTIONS and the actual response, then test allowed origins, rejected origins and cookie behavior.
Frequently Asked Questions
Can I paste an entire HTTP header block?
Use one Content-Type value or Content-Type: line per line here. Other headers such as Accept or Content-Disposition belong in HTTP Headers Parser.
What happens to invalid or duplicate parameters?
The line is reported as failed with a reason. A missing multipart boundary is a warning on an otherwise parsed media type; a declared boundary is not compared with a request body.
What does normalization change?
It lowercases type, subtype, and parameter names, standardizes separators, and retains required quoting. Parameter values keep their case and content. It does not convert a charset or certify a request.
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