Free and open source hex viewer/editor written in Java.

Features:

• Visualize data as numerical (hexadecimal) codes and text representation
• Codes can be also binary, octal or decimal
• Support for Unicode, UTF-8 and other charsets
• Insert and overwrite edit modes
• Searching for text / hexadecimal code with matching highlighting
• Support for undo/redo
• Support for files with size up to exabytes