HexEdit is a Java 1.4 graphical (GUI) application to edit a file as a stream of hexadecimal digits,where each 8-bit byte is represented by two 4-bit “nibbles�? (the hex digits). No meaning is attached to the digits, and hence to the contents of the file, so this editing is very raw. You can insert, delete, or replace digits or bytes, and you may view an approximate character equivalent of the digits in plain text (7-bit ASCII). The primary purpose of a hex editor is to patch or correct specific locations within a file without affecting the rest of the file, something that most word processors can’t do. A secondary purpose is to view the exact content of files. (To generate a hex dump and save this dump to a file, see the DumpFile application.)

The application window has two portions. The top portion has standard Java buttons and options. The bottom portion has a hexadecimal dump with three regions: file offsets on the left, bytes in hexadecimal in the middle, and ASCII text on the right. The bottom looks like an old video terminal (quite deliberately), with a color scheme to match. The Java buttons and options are straightforward after some experimentation. Don’t worry: no files are changed unless you click on the “Save File�? button. In fact, files aren’t saved by default, so if you click on the Exit button without saving, any changes will be lost. This may differ from what you expect with word processors or other types of editors.