Is my file uploaded to a server?

No. The tool uses the FileReader API to read only the first 16 bytes locally in your browser. Nothing leaves your device.

Why might the detected type differ from the file extension?

File extensions can be renamed or spoofed. Magic bytes are embedded in the file itself and reveal its true format regardless of the extension.

Which file types can be detected?

JPEG, PNG, GIF, PDF, ZIP, RAR, 7z, MP3, MP4, WebP, DOCX/XLSX (ZIP-based), EXE, BMP, TIFF, WAV, OGG, FLAC, and more.

What if my file type is not recognized?

The tool shows 'Unknown' and still displays the raw hex bytes so you can look them up manually.

Developer 無料サインアップ不要

File Type Detector

Identify any file's true type by reading its magic bytes — no upload required.

ツールを読み込み中…

このツールについて

Drop or select any file and this tool reads just the first 16 bytes in your browser to identify the file's true type from its magic number signature. Results include the detected file type, MIME type, a plain-English description, and the raw hex bytes. A reference table of over 20 common file signatures is shown for quick lookup. Nothing is uploaded to any server — all detection happens client-side.

使い方

1 Click 'Choose File' or drag and drop a file onto the drop zone.
2 The first 16 bytes are read instantly in your browser.
3 View the detected file type, MIME type, description, and hex dump.
4 Scroll down to see the full reference table of magic byte signatures.

このツールについて

使い方

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