HexCmp 2.34.14 for Windows

HexCmp 2.34.14 is a Windows program from Fairdell Software for comparing binary files and editing them at the byte level. It shows two files side by side in hexadecimal and text form and highlights every byte that differs. The download is under a megabyte, and you can download HexCmp for Windows from fairdell.com.

Overview

Text comparison tools work well for source code and documents, but they are useless with binary data: executables, firmware images, save files, database files, images. There, the only way to see what changed is to look at the bytes. HexCmp puts two such files next to each other, scrolls them in sync and marks the differences, so you can jump from one changed block to the next. Built-in hex editing lets you change values directly, which is useful for patching a configuration byte or repairing a damaged header. Typical users are developers checking whether two builds are really identical, reverse engineers and security researchers studying what an update changed, technicians comparing firmware dumps, and gamers or modders analysing save files. It also helps in data recovery, where you compare a damaged file with a healthy one of the same type. The interface is technical by nature; basic knowledge of hexadecimal notation is expected.

Getting started

1. Download HexCmp from the Fairdell downloads page and install it.
2. Open the two files you want to compare.
3. Use the next and previous difference commands to move between changed blocks.
4. Switch the display between hex and text to recognise strings inside the data.
5. Save edits to a copy, never to your only original.

Product details are on the official HexCmp page.

Reading the comparison

Each row shows an offset, the position in the file, followed by bytes in hexadecimal and their text representation. When differences appear only in a small block near the start, the change is often in a header or a version field. Differences spread across the whole file usually mean compression or encryption, where a small change in content alters everything after it. In that case, comparing byte by byte tells you little, and you need to unpack the data first.

Working safely

• Always keep a backup before editing a binary file.
• Changing executables can trigger antivirus warnings and break digital signatures.
• Respect licences: modifying software you do not own the rights to may breach its terms.

Key facts

Pros and cons

• Pro: side-by-side binary comparison with highlighted differences.
• Pro: built-in hex editing.
• Pro: tiny download.
• Con: technical interface for beginners.
• Con: edits to binaries can easily break files without a backup.

Alternatives

For comparing and editing text files, Notepad++ is in our listings. Total Commander includes a basic file comparison function for everyday use.