File Signature Inspector

Magic Bytes & MIME Detector

Inspect binary magic bytes, verify true file formats, detect extension spoofing, and view formatted hex dumps

Binary Magic Bytes Analyzer

Inspect raw file headers, detect spoofed extensions, and examine the hex dump (100% Client-Side)

Quick Samples:

Drag and drop any file here, or click to browse

Any file type (PDF, EXE, JPG, ZIP, Word, ELF, Video). Only the header bytes are read locally inside your browser; nothing is uploaded.

What is File Signature Inspector?

The File Signature Inspector analyzes the binary header bytes (magic numbers) of any uploaded file to determine its authentic file format and MIME type. Attackers frequently disguise malware or script files by changing their extension (e.g. naming an executable file invoice.pdf). This tool reads the raw binary header, matches it against a comprehensive signature database, displays an interactive hex dump, and alerts you if an extension mismatch is detected.

How to Use File Signature Inspector

Upload or drag a file

Select any file from your computer to inspect its binary signature.

Inspect true format

View the identified true MIME type, standard extensions, and description.

Check extension safety

Review the safety badge to see if the file's declared extension matches its actual binary content.

Explore hex dump

Examine the formatted hexadecimal and ASCII representation of the first 64 bytes.

Key Features

Database of 120+ file signatures covering executables, images, archives, documents, and media

Extension spoofing detection: flags renamed files that conceal dangerous formats

Interactive Hex Dump viewer (Hex offset, byte hex values, and ASCII representation)

Detects true MIME types, standard extensions, and file container architectures

100% Client-side inspection: only the first few bytes are read, nothing is uploaded

Tips & Best Practices

1
Always inspect unexpected email attachments that claim to be PDFs or images to ensure they aren't disguised executables.
2
ZIP-based files (DOCX, XLSX, APK, JAR) all share the PK signature (0x50 0x4B 0x03 0x04).
3
Unix shell scripts and ELF binaries have distinct header magic bytes (#! and 0x7F 'E' 'L' 'F').

Why Use Our Online File Signature Inspector?

File Signature Inspector gives developers a fast, distraction-free utility that runs entirely client-side. No accounts, no data sent to any server, no extensions to install. Paste your input, get your output, copy to clipboard — designed to slot into your daily workflow without breaking your flow.

Client-SideCode stays private

Zero SetupNo installs needed

Copy to ClipboardOne-click workflow

Open StandardsCommon formats

Frequently Asked Questions

What are file magic bytes?

Magic bytes are specific constant byte sequences at the very beginning of a file that operating systems and programs use to identify the file format, regardless of its extension.

Does this upload my file to a server?

No. The inspection runs entirely in your browser using the HTML5 File API to slice only the header bytes.

Can malware hide its magic bytes?

A program cannot execute as a valid binary without the operating system recognizing its true header, making magic bytes one of the most reliable detection techniques.

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