Hex Editor

What Is a Hex Editor

A hex editor displays and allows editing of binary file data in hexadecimal (base-16) format, alongside ASCII/Unicode text representations. Unlike text editors that interpret files as readable characters, hex editors show the raw bytes that compose a file — enabling inspection and modification of any file at the binary level.

Hex editors are indispensable tools for reverse engineering, forensic analysis, malware research, file format investigation, data recovery, and low-level debugging. They reveal the true content of files regardless of format, extension, or encoding.

How Hexadecimal Representation Works

Each byte (8 bits) is displayed as two hexadecimal digits (00 to FF), representing values from 0 to 255:

Decimal	Binary	Hex	ASCII
0	00000000	00	NUL
65	01000001	41	A
90	01011010	5A	Z
97	01100001	61	a
255	11111111	FF	(non-printable)

A typical hex editor displays data in three columns: offset (position), hexadecimal bytes, and ASCII interpretation. Non-printable bytes appear as dots in the ASCII column.

Common Use Cases

• File format analysis: Examine file headers, magic numbers, and internal structure to understand or reverse-engineer file formats
• Malware analysis: Inspect suspicious executables for embedded strings, URLs, IP addresses, and encoded payloads without executing them
• Data recovery: Locate and extract data fragments from corrupted files or disk images by searching for known byte patterns
• Firmware inspection: Examine embedded device firmware for hardcoded credentials, certificates, and configuration data
• Forensic investigation: Search seized storage media for specific byte sequences — file signatures, keywords, or data fragments
• Game modding: Modify save files, resource files, and configuration data in applications and games

Best Practices

1. Always work on copies — Never hex-edit original files. Create a working copy to prevent irreversible corruption of evidence or important data.
2. Learn common magic bytes — Recognizing file signatures (PDF: 25 50 44 46, PNG: 89 50 4E 47, ZIP: 50 4B 03 04) accelerates file identification and analysis.
3. Use the ASCII pane for string hunting — Readable strings (URLs, paths, error messages, passwords) are immediately visible in the ASCII column. Search for known strings to find relevant sections quickly.
4. Understand endianness — Multi-byte values (integers, pointers) may be stored in little-endian (x86) or big-endian (network, MIPS) byte order. Misreading endianness leads to incorrect value interpretation.
5. Compare files with diffing — When analyzing changes between file versions, use hex diff tools to highlight modified, added, and removed bytes rather than scanning manually.