Your files stay on your device

# File type and magic byte detector

Drop a file and learn its real type from signature bytes rather than the extension, with container inspection and mismatch flags.

Drop files to identify them

Any format · first 64.0 KB read per file · stays on your device
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Drop files to identify them from their bytes.

The detector reads signature bytes and looks inside the two big container families: ZIP member names separate DOCX, XLSX, PPTX, JAR, APK and EPUB, and the RIFF form type separates WAV, AVI and WebP. It does not scan file contents beyond the 64 KB window, does not run virus checks, and can be fooled by a file crafted to start with another format's bytes. Plain text has no signature, so CSV, JSON and source code are honestly reported as unrecognized.
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## More PDF & file tools

- [Image metadata editor](/files/metadata)
- [Photo location and metadata](/files/exif)
- [ZIP files](/files/zip)
[All PDF & file tools](/files)

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Canonical HTML: https://nutter.tools/files/file-type-magic-byte-detector
Markdown version: https://nutter.tools/files/file-type-magic-byte-detector.md
Plain-text version: https://nutter.tools/files/file-type-magic-byte-detector.txt
Agent index: https://nutter.tools/llms.txt