Free "Hex" Editors

• Introduction
• Frhed - Free hex editor
• HxD -- is also a Disk editor
• HexIt
• MS-DOS EDIT.COM
• XVI32 Hex editor
• Hex Edit

Introduction

    Although some Hex Editors can even display a text file the same way Text Editors do (and all of them should at least show you the ASCII text characters on part of the screen), Hex Editors excel at two things that are impossible for most text editing programs:

  1) Showing you every single byte that makes up a file (any kind of file; including executable programs), and

  2) Saving the file with only the changes that you make; unlike many old  Text Editors which always add a couple extra bytes at the end of each file^* ( See note below).

    Also, most Text Editors will drastically change or even truncate binary files (chop off a large portion at the end of the copied file when loading it into the editor), so you should never use a Text Editor to make changes to a file unless you know for sure it's a plain text type file!

Although I'm trying to comment on a number of helpful 'free' Hex editors here, the first one on the list (FRHED) is, in my opinion, the best everyday workhorse; a program for searching through and making changes to dozens of files per session on a daily basis.

HxD by Maël Hörz.
Maël's Home Page.

New: Tutorial using HxD

HxD is a proven Hex Editor not only for editing any binary files on your system but also for editing your hard disk drive sectors from within Windows™ 2000/XP! This made it the first FREE Disk Editor that can do many of things people purchase the commercial editor WinHex for! HxD is still being developed, and its author continues to be interested in any bugs you might possibly find and open to suggestions for new features! HxD already has all the basic features you would want in such an editor: Both Hex and ASCII (including Unicode) search/replace, and will open files, memory locations, hard drives (as either logical or physical) and disk image files too. The program was written in Delphi. Here's a view of HxD.exe inside of HxD after it found and highlighted a location for the string "Delphi" using its "Search" menu:

And here's a view showing our hard disk's Master Boot Record (the first sector of our PC's physical hard disk, "Hard Disk 1,") along with TABs at the top where HxD.exe remains open, with the Memory locations for an instance of NOTEPAD. You can just barely see a light-gray line; between offsets 1FFh and 200h, separating Sector 0 and Sector 1 (each sector being comrpised of 512 bytes). The new controls and specifically the "Sector" box at the top the window are for jumping directly to a desired Sector:

HexIt by Mikael Klasson.
Mikael's Home Page, or:
Direct to The HexIt Homepage.

I'm listing this editor here for a special reason: Because it can be used to disassemble x86 machine code Instructions up to and including those requiring a Pentium II CPU (with MMX) along with all FPU instructions as well; whereas the disassembler in DEBUG can only do so for the old 8086 CPU and 8087 FPU instructions. If you're completely dependent upon GUI interfaces, you probably won't like this program, but there are very few free programs that can do this! See the documentation for a list of many other features, and make sure to read the help file for its many keyboard commands.

Part of HexIt in Code Mode in a DOS-window:

It looks much better when run at full-screen.

Part of HexIt in Hex Mode in a DOS-window:

(Note: Pic of display has been slightly altered to fit my web page parameters.)

MS-DOS Editor (EDIT.COM)
version 2.0.026 ©1995 or later by Microsoft
      Yes, I mean the old Edit.com program that comes standard with all Microsoft OSs! I wanted to point out that in a 'pinch' when nothing else is available or accessible for some reason, this program can be used as a Hex editor (something which most of today's GUI-dependent users don't know!)

If you never bothered to look at the 'helps' for Edit.com or start the program without using a filename parameter, you might never realize there's a BINARY Mode. You can open a binary file from a command line using: edit /nn path\file.ext   where 'nn' specifies how many characters you want to see on each line before they wrap around onto the next line ( there are no normal line endings even for a text file opened in Binary Mode, since all characters such as Carriage Return or Line Feed are simply displayed along with all the other bytes. So you have to tell Edit.com where it should end each line! For example, I chose 64 characters in the display below. )

The second method for turning on Binary Mode is by selecting it from the OPEN file dialog box like this:


And here's how the file appears when you open it:

      The first thing you might notice is that you'll have to place the cursor (yellow in the pic above) under a character to see its byte value (shown in the red circle)! Other reasons why Techs avoid using Edit.com for making changes to BINARY files are:

1) The byte values are shown only in Decimal (not Hex).
2) It can be very DIFFICULT to enter a byte value that's not directly accessible from the keyboard -- If you try using the method of 'ALT key plus byte value' from the Number Keypad, you'll quickly find that most of the Control Code values (0-31) are used by Edit.com to carry out cursor movements and other functions! If you're stuck with having to use Edit.com, I suggest creating a small file comprised of at least the byte values 0 through 31 that you can COPY a value from and then PASTE it into the target file.
3) You can't really tell where the end of the file is unless you first press the 'CTRL + END' keys, go UP one line to the actual last line of the file, press the END key and finally go one character to the LEFT! This last step is because Edit.com always places the cursor AFTER the last byte in a line rather than under the last byte in a line. So, why all the hassle? It's because Edit.com creates a screenful of spaces (byte value 32) at the end of each line and a blank line at the end of the file WHILE you are editing a file. (None of these bytes are ever included when you actually SAVE the file though.)
4) Edit.com won't find any character strings you search for if they start on one line and continue to the next! E.g., it can't find 'CD' in the file shown above (just 'cd'). See below for more on Search problems!
5) You can't see any differences between the byte values 0, 32 and 255 on the display.

    But for all its faults, Edit.com is almost guaranteed to be on a Windows system (just like DEBUG), and might be OK for changing a quick byte or two in a small file; assuming you know how to FIND those bytes(!)... Why? Rather than just being very difficult (as it is when trying to enter certain bytes into the edit window), it's almost impossible to place the byte values 0 (Null - no affect), 8 (BACKSPACE), 9 (TAB), 13 (Line Feed) or 27 (ESC key) into the Search box without having those actions take place! For the other control characters, you can use the 'ALT key plus Number Keypad' method mentioned above.

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XVI32 Hex-Editor by Christian Maas.
This is a very good and stable entry in the class of 'free' Hex editors. However, some comments here are based upon my personal preferences as one who opens many instances of binary files daily. If you're new to binary file editing, or have specific changes you want to make to certain files, this program may be just right for you!

The author of this program is concerned about anything you might perceive as a 'bug.' And although in the past I had used the words 'Negative review' to describe his program here, he was very professional in his email to me and took the time to make some changes in his program!


Control characters can now appear as blank spaces in the 'text' window, and the old 'grid pattern' display around all the bytes and characters has been moved to an options menu. Although the author did make some changes trying to cure the main drawback I had with his older version, it's still a problem for me. He reduced the rate at which the program scrolls through files when using the Arrow/Page keys, but the ASCII characters in the text window still 'jump' (like using a page up/down key) rather than scroll through the data. And more importantly, if you have very large files to examine, trying to increase the rate by using the mouse on the 'scroll bar,' keeps the characters from ever changing in the text window (you'll see the word 'scrolling' near the bottom of the display) until after you release it. This makes it impossible to scan large files with your eyes at a reasonable rate; something I do quite often when looking through system files or files that might contain viruses, or when searching for any number of interesting patterns which are unknown to me at the time. Christian is aware of this, but appears to be unable to do anything about it due to the kind of software he uses.

 

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HexEdit by Andrew W. Phillips
Free from Simtel (FTP): hexfre20.zip.

V 2.6 HexEdit Homepage.
( Note: Only HexEdit version 2.0 is free; the latest version 2.6 is commercial !! )
  If you want a large Windows program with lots of colored buttons to push, give this one a try. Actually it may be quite helpful for those who've never used a Hex editor before. It has a very nice Introduction (in the Windows Help file) which explains quite a bit about using a Hex editor, various file types and extensions you're likely to come across and some of the terms used in Hex editing.

( Note: If you use a 640 x 480 display, try pressing the 'Decrease Font Size' button until all the characters in the program window fit your screen size.)

Though MS-DOS certainly didn't need an 'End-of-File' marker (the Directory entries contained the exact length of each file; just as FAT32 or NTFS FILE entries still do today), you may need to press the 'CTRL' and 'Z' keys under DOS to let some app. or command know that it's reached the 'End of your input'. For example, when you enter: copy con newfilename  at a DOS prompt, you must finish your input with a ^Z character by pressing the Control and then Z keys without letting up the Control key. This will still work under a Win2000/XP/2003 DOS-box!

Updated: 10 JUL 2008 (Link to HxD Tutorial).
Updated: 20 NOV 2010 (New pictures for HxD).