Content-Type Inspect
Parse and diagnose HTTP headers and routing signals in your browser. No input is sent to a server. Use it for first-pass observation-gap 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 Content-Type and click “Parse”. It shows MIME type and parameters.
Notes (this tool)
- Accepts a Content-Type: header line.
About this page
What does this tool do?
Split Content-Type into MIME type and parameters (charset/boundary, etc.).
Useful for troubleshooting API responses and file delivery.
Content-Type basics
- MIME type is “type/subtype” (e.g., application/json).
- charset specifies the text encoding.
- multipart/form-data requires a boundary.
Syntax (how to read)
Content-Type is formatted as “MIME-type; key=value; key=value...”. The first token is the MIME type followed by parameters.
- application/json; charset=utf-8
- text/html; charset=UTF-8
- multipart/form-data; boundary=----...
Why MIME type matters
MIME type tells clients how to interpret content. If it’s wrong, rendering, downloads, and parsing can behave unexpectedly.
- API returns text/html → it might be an error page
- JSON garbles due to unexpected charset
Typical use cases
- JSON returned as text/html
- Downloads break or text becomes garbled
- Form boundary mismatch breaks server parsing
Parameter examples
- text/html; charset=UTF-8
- application/json; charset=utf-8
- multipart/form-data; boundary=----WebKitFormBoundary...
charset (encoding) notes
For textual responses (text/*, HTML, CSV, etc.), charset is important. If omitted, clients may guess and cause garbled text.
- HTML: text/html; charset=UTF-8
- CSV: text/csv; charset=UTF-8
multipart and boundary
multipart/form-data is used for form submissions and file uploads. The boundary is a delimiter; if it does not match the body, servers cannot parse it.
- When crafting manually, boundary must match the body delimiters
- Usually generated automatically by browsers/HTTP libraries
Common pitfalls
- Missing charset causes garbling
- Wrong MIME type leads to misinterpretation
- Boundary mismatch breaks multipart parsing
Debugging workflow (recommended)
- Copy Content-Type from DevTools/logs and parse it
- Check if MIME/charset match expectations
- For multipart, verify boundary presence and consistency
Related tools
- HTTP Header Parser: extract Content-Type from header lists
- Request Headers Parser: check request-side Content-Type
- JSON Formatter/JSONC Formatter: validate/format JSON
What this tool does
- Extract MIME type
- Show parameters like charset/boundary
- Normalize and list values
Operational notes
- Intermediaries may rewrite headers. Compare captures from equivalent points.
- Confirm final decisions with server logs and configuration such as trusted proxy and routing.
Referenced specs
- RFC 9110 (HTTP Semantics)
- RFC 2045/2046 (MIME)
FAQ
Is charset required?
For text types it’s safer to set it. JSON is usually UTF-8, but explicit is better to avoid issues.
Where does the boundary come from?
The client (browser/library) generates it. It must match the body delimiters.
application/json vs text/json?
application/json is the recommended standard. Using standard types avoids client-specific quirks.
References
Next to view (diagnostic order)
These links are generated from site_map rules in recommended diagnostic order.
- X-Content-Type-Options Inspect — Parse X-Content-Type-Options and validate nosniff
- Response Headers Parser — Parse response headers into structured data
- HTTP Header Parser — Parse raw headers into structured lists
- Link Header Inspect — Parse Link headers and inspect rel/as/type
- Security Headers Audit — Audit presence of major security headers
- How to Diagnose JS/CSS Blocks from nosniff Mismatch — Trace Content-Type vs nosniff mismatches, fallback responses, and delivery-layer rewrites
- How to choose response header tools — Map Retry-After, Server-Timing, Link, Content-Type, and nosniff checks by symptom
- Set-Cookie Builder — Build Set-Cookie headers with attributes
Same-theme links
Response Header Diagnostics
Step through raw headers to inspect Retry-After, Server-Timing, Link, and Content-Type
- HTTP Header Parser — Parse raw headers into structured lists
- Response Headers Parser — Parse response headers into structured data
- Set-Cookie Inspect — Parse Set-Cookie attributes and review delivery policy
- Cookie Domain/Path Matcher — Evaluate cookie send conditions by Domain/Path/Secure
- SameSite Cookie Simulator — Simulate cookie send behavior from SameSite and request context
- Set-Cookie Conflict Checker — Detect same-name cookie conflicts and overwrite risks
- Cookie Size Checker — Estimate Cookie header size and check limit risks
- Retry-After Inspect — Parse Retry-After and inspect retry wait behavior
- Server-Timing Inspect — Parse Server-Timing and inspect latency metrics
- Link Header Inspect — Parse Link headers and inspect rel/as/type
- X-Content-Type-Options Inspect — Parse X-Content-Type-Options and validate nosniff
- HTTP Status Inspect — Analyze HTTP status codes and suggest handling direction