Synalyze It! is a free hex editor for Mac OS X based on the Cocoa framework. It helps you to understand the contents of binary files by interactively defining a "grammar" for a certain file format. Additionally an incremental search for text, numbers or masks is include. You can display all strings of a file or a histogram over the bytes in a file. There are already some grammars available to decode common file formats, but you can create your own. The contents of a file are decoded automatically and displayed as different colors. Also you can compare some bytes translated to differnt code pages.