File Type Detector
Identify a file's real type from its magic bytes and see whether the extension matches.
Find out what a file really is
An email attachment without an extension, a '.jpg' that won't open or a suspicious download… File extensions are easy to change, but most formats carry a fixed signature (magic bytes) in their first bytes. The File Type Detector reads that signature to identify the file's real type.
Recognised types
- Images: JPG, PNG, GIF, WebP, HEIC, AVIF, BMP, TIFF
- Documents: PDF and Office files (DOCX, XLSX…)
- Archives: ZIP, RAR, 7z, GZIP
- Audio and video: MP3, WAV, MP4, MKV, WebM
- Fonts, executables and text formats
For security
Check whether a 'document' is really an executable (.exe) before opening it. The file is inspected in your browser and never uploaded.
How to use File Type Detector
- Choose the file to inspect.
- The tool reads the file's first bytes.
- Review the detected type and extension match.
- Rename the file with the right extension if needed.
Why use this tool?
Fixes files that won't open and adds an extra check against disguised malicious files.
FAQ
Can a file lie about its type?
The extension can be anything, but the first bytes of most formats follow a fixed signature, which is what this tool reads.
Why does a DOCX show as ZIP?
DOCX, XLSX and PPTX files are actually ZIP archives; the tool tries to tell them apart by their contents.
Does it scan for viruses?
No. It only identifies the file type; use an up-to-date antivirus for suspicious files.
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