JSON payload sent as `text/plain`
Bad input: Gateway forwards JSON body but content-type is plain text.
Failure: Downstream parser skips JSON decoding and validation.
Fix: Normalize content-type at ingress and enforce contract checks.
Content-Type Parser (MIME, Charset, Boundary)
Parse Content-Type headers and extract MIME parameters
API & HTTP
π 100% client-side β your data never leaves this pageMaintained by ToolsKit Editorial Teamβ’Updated: May 19, 2026β’Reviewed: May 19, 2026
Page mode
Content-Type Input
Quick CTA
Paste a Content-Type header to inspect MIME, charset, boundary, and params immediately; troubleshooting hints stay in Deep.
Output
Parsed result will appear here
100% client-side
Page reading mode
Deep expands pitfalls, recipes, snippets, FAQ, and related tools when you need troubleshooting or deeper follow-through.
About this tool
Content-Type Parser helps you parse and normalize HTTP Content-Type header values in seconds. Paste one or multiple lines like application/json; charset=utf-8 or multipart/form-data; boundary=----WebKitFormBoundary and get structured output: media type, subtype, charset, boundary, plus extra parameters. It is useful when APIs fail due to malformed headers, file uploads break because of boundary issues, or clients reject responses because of incorrect content type formatting. The parser also marks invalid lines so you can quickly locate syntax mistakes before deployment. All parsing runs locally in your browser.
Compare & Decision
Content-Type Parser vs Content-Type Generator
Parser
Use it when you already have a header value and need to inspect or debug it.
Generator
Use it when you need to construct a clean value from scratch for a new request or response.
Note: Parse first to understand what is wrong; generate next when you need a canonical replacement.
Auto-generated multipart headers vs manual header override
Auto-generated header
Use it in most client SDK flows to avoid boundary mismatch mistakes.
Manual override
Use it only in controlled debugging or custom protocol tooling.
Note: Manual override is powerful but easy to misalign with the actual payload body.
MIME token parsing only vs MIME + charset validation
Token only
Use for rough categorization dashboards.
Token + charset
Use for payload decoding and interoperability testing.
Note: Incorrect charset is a common source of invisible data corruption.
Accept vendor MIME loosely vs enforce registered media types
Loose vendor accept
Use during exploratory integrations.
Strict media registry
Use in production API contracts and gateway policy.
Note: Strict enforcement improves compatibility across clients and proxies.
Fast pass vs controlled workflow
Fast pass
Use for low-impact exploration and quick local checks.
Controlled workflow
Use for production delivery, audit trails, or cross-team handoff.
Note: Content Type Parser is more reliable when acceptance criteria are explicit before release.
Direct execution vs staged validation
Direct execution
Use for disposable experiments and temporary diagnostics.
Stage + verify
Use when outputs will be reused by downstream systems.
Note: Staged validation reduces silent compatibility regressions.
Failure Input Library
Charset mismatch breaks non-ASCII characters
Bad input: UTF-8 body labeled as ISO-8859-1.
Failure: Multilingual text appears garbled in clients/logs.
Fix: Align charset metadata with actual body encoding.
Input assumptions are not normalized
Bad input: Boundary values are not covered by acceptance fixtures.
Failure: Output appears valid locally but fails during downstream consumption.
Fix: Normalize contracts and enforce preflight checks before export.
Compatibility boundaries are implicit
Bad input: Security-sensitive values leak into debug traces.
Failure: Same source data yields inconsistent outcomes across environments.
Fix: Declare compatibility constraints and verify with an independent consumer.
Direct Answers
Q01
Can this help explain a 415 Unsupported Media Type response?
Yes. Parse the exact header value first and check whether the media type, charset, or boundary is malformed or missing.
Q02
What does boundary matter for multipart/form-data?
The server needs the boundary token to split the body into parts. Missing or mismatched boundaries often break file uploads.
Quick Decision Matrix
Internal debugging of unknown third-party responses
Recommend: Start with tolerant parsing, then annotate anomalies.
Avoid: Avoid hard-failing before basic inspection.
Production API boundary enforcement
Recommend: Use strict parser plus charset validation gates.
Avoid: Avoid accepting ambiguous or malformed content types.
Local exploration and temporary diagnostics
Recommend: Use fast pass with lightweight verification.
Avoid: Avoid promoting exploratory output directly to production artifacts.
Production release, compliance, or cross-team handoff
Recommend: Use staged workflow with explicit validation records.
Avoid: Avoid one-step execution without replayable evidence.
Failure Clinic (Common Pitfalls)
Boundary is missing from multipart/form-data
Cause: The header says multipart/form-data, but the required boundary parameter is absent or malformed.
Fix: Use the parser to confirm the boundary format, then regenerate the header with a matching boundary token.
Charset formatting is inconsistent
Cause: Teams mix quoted and unquoted charset values or drop the charset entirely for text payloads.
Fix: Normalize the header format and keep one charset convention across docs, clients, and servers.
Manually copying a boundary value that does not match the request body
Cause: If header boundary and payload separators differ, servers cannot split multipart sections correctly.
Fix: Let the client library generate multipart boundaries automatically, or ensure header and body are produced together.
Scenario Recipes
01
Triage a 415 response quickly
Goal: Validate a failing Content-Type line before rebuilding the request or changing gateway rules.
- Paste the exact Content-Type value from the failing request.
- Inspect the normalized output and parsed parameters.
- Fix malformed tokens, then retest with the corrected header.
Result: You can confirm whether the 415 comes from header syntax, missing parameters, or a true media-type mismatch.
02
Diagnose upload 415 after gateway migration
Goal: Validate whether a failing multipart request has a malformed media type or missing boundary.
- Paste the exact `Content-Type` header from the failing request trace.
- Check parsed parameters and verify boundary token presence.
- Regenerate the header with a matching boundary and retest the upload endpoint.
Result: You can quickly separate true media-type incompatibility from header formatting errors.
03
Content Type Parser readiness pass for incident replay diagnostics
Goal: Validate assumptions before output enters shared workflows.
- Run representative samples and capture output structure.
- Replay edge cases with downstream acceptance criteria.
- Publish only after sample and edge-case checks both pass.
Result: Delivery quality improves with less rollback and rework.
04
Content Type Parser incident replay for rollback prevention drills
Goal: Convert recurring failures into repeatable diagnostics.
- Rebuild problematic inputs in an isolated environment.
- Compare expected and actual outputs against explicit pass criteria.
- Document reusable runbook steps for on-call and handoff.
Result: Recovery time drops and operational variance shrinks.
Production Snippets
Paste-ready validation sample
HTTP
application/json; charset=utf-8
multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gWSuggested 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)
A practical problem page for debugging 415 errors with exact header checks and copy-ready fixes.
CORS Credentials + Wildcard Origin Error: Practical Fix Guide
Fix the classic browser CORS block when credentials are enabled with Access-Control-Allow-Origin=*.
Use It In Practice
Content-Type Parser (MIME, Charset, Boundary) is most reliable with real inputs and scenario-driven decisions, especially around "Internal debugging of unknown third-party responses".
Use Cases
- When Internal debugging of unknown third-party responses, prioritize Start with tolerant parsing, then annotate anomalies..
- When Production API boundary enforcement, prioritize Use strict parser plus charset validation gates..
- Compare Parser vs Generator for Content-Type Parser vs Content-Type Generator before implementation.
Quick Steps
- Paste the exact Content-Type value from the failing request.
- Inspect the normalized output and parsed parameters.
- Fix malformed tokens, then retest with the corrected header.
Avoid Common Mistakes
- Common failure: Downstream parser skips JSON decoding and validation.
- Common failure: Multilingual text appears garbled in clients/logs.
Frequently Asked Questions
What can this parser extract from Content-Type?
It extracts media type, subtype, charset, boundary, and any extra parameters from each Content-Type line.
Can it parse multipart/form-data boundaries?
Yes. It reads boundary values from multipart/form-data headers and highlights malformed boundary syntax.
Can I parse multiple header lines at once?
Yes. You can paste multiple Content-Type lines in one input and review parsed results line by line.
Why do APIs fail with 415 Unsupported Media Type?
A common reason is wrong or malformed Content-Type. Verify exact MIME type and required parameters such as charset or boundary.
Does this tool validate header format?
Yes. Invalid lines are flagged so you can detect syntax errors before sending requests in production.
Does this parser run client-side?
Yes. All parsing happens in your browser and no header content is uploaded.