How do magic bytes work?

Most binary file specifications require specific constant signature bytes at the very beginning of the file (e.g. %PDF for PDFs, or PK for ZIP archives).

Digital Tools Kits300 Free Online Tools

Image Tools100% In-Browser & Private

File Type Detector

Detect true file MIME types and extensions by inspecting magic byte signatures.

How to Use File Type Detector

1Upload or drop any unknown, extensionless, or suspicious file.
2The tool inspects the initial byte header signatures.
3Review the detected MIME type, recommended extension, and magic hex bytes.

Key Features & Benefits

Magic number byte signature database (PNG, JPEG, PDF, ZIP, MP4, WebP, etc.)
Displays raw hexadecimal byte preview of file header
Identifies mismatched or spoofed file extensions
Zero server uploads: completely safe for sensitive files

About File Type Detector

Identify true file formats regardless of spoofed or missing file extensions. Reads the first 32 header bytes (magic numbers) to detect PNG, JPEG, PDF, ZIP, MP4, WebP, and audio files.

Unlike traditional web tools that send your personal data, uploaded photos, or sensitive text to remote cloud servers, our File Type Detector operates strictly inside your client browser sandbox. This guarantees high processing speeds without network throttling, and ensures your data privacy is completely preserved.