File Type Detector
Detect a file's true type by reading its binary signature, not just its file extension.
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Detects the real file type from its binary signature
How It Works
- 1Upload a file.
- 2Its first bytes are checked against known file signatures.
- 3See the detected type instantly.
Features
- Detects common image, archive, audio and document formats
- Flags mismatched extensions
Privacy
This tool runs entirely in your browser — your files are never uploaded to a server.
About File Type Detector
Most operating systems decide what a file 'is' by looking at its extension, but an extension is just a label in the filename — anyone can rename example.exe to example.jpg and the extension alone won't catch it. Real file formats generally embed a signature, often called magic bytes, in the first few bytes of the file itself: a PNG always starts with the same eight-byte sequence, a ZIP-based format starts with 'PK', and so on. This tool reads those leading bytes and compares them against a list of known signatures instead of trusting the name after the dot.
That makes it useful for confirming an unlabeled or suspiciously named file is actually what it claims to be, checking a batch of downloads before opening them, or figuring out the format of a file someone sent you without an extension at all. It flags a clear mismatch when the detected signature disagrees with the extension, which can indicate the file was renamed, mislabeled, or isn't what it appears to be.
Detection only covers the signatures built into the tool, and some formats — plain text, CSV, and a few others — have no consistent binary signature to check in the first place, so they'll show as unrecognized rather than misidentified.