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File Format Inspector – Extension vs Content Mismatch Detector
x402
File Format Inspector – Extension vs Content Mismatch Detector is a paid API for AI agents from file-formats.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-30).
Compares a file's declared extension against its actual type inferred from the first bytes, flagging disguised executables or mismatched file types.
Price / call$0.02
Success—
StatusUnknown
How this service works
Compare a file name's extension with its real type from the first bytes; flags executables disguised as documents or images.
Output
Returns a verdict on whether the file extension matches the detected content type, including the detected MIME type, detected type label, detected category, whether a double extension was found, a human-readable summary, a list of reasons supporting the verdict, and any disclaimers or caveats about the analysis.
Example use cases
Email attachment security check
“Someone sent me a file named report.pdf but I'm suspicious — the hex bytes start with 4D5A which I think is an EXE signature. Can you compare the extension against the actual content type to see if it's disguised malware?”
File upload validation for web app
“A user uploaded photo.jpg to our platform. Here are the first 512 bytes as hex: 504B0304... — can you verify whether the extension matches what the file actually is, and flag it if it looks like a disguised executable?”
Double extension phishing detection
“I have a suspicious file called document.docx.exe and its hex header starts with 4D5A9000. Check whether the extension matches the real file type and tell me if this looks like a double-extension trick.”
Technical details
Endpoint
GEThttps://file-formats.x402tookit.com/extension-vs-content?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need to cross-validate a file's declared extension against its actual binary signature — especially for security-sensitive upload pipelines, email attachment screening, or anti-phishing workflows. Prefer it over a generic MIME-type identifier when you specifically need to compare the claimed name against the true type and get a pass/fail verdict with reasons.
Side effects
- Missing filename or hex query params — returns validation error
- Hex string too short to identify file type — may return inconclusive result
- Unrecognized magic bytes — detected type may be null or generic
- Degraded mode if signature database is partially unavailable — degraded flag set to true
- Non-hex characters in hex param — likely parse error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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