There's also 010 Editor, which has a very similar thing for creating file format grammars. Invaluable if you work with complex binary files regularly. The scri

There's also 010 Editor, which has a very similar thing for creating file format grammars. Invaluable if you work with complex binary files regularly. The scriptable functionality to decode a file format that this and Synalyze It do makes them my two favourite hex editors. This hex editor looks like a great start, though :)