Hex Fiend 2.0

Hex Fiend is a fast and clever open source hex editor for Mac OS X.
Hex Fiend does not limit you to in-place changes like some hex editors.

It can handle as big a file as you’re able to create. It’s been tested on files as large as 118 GB. Hex Fiend does not keep your files in memory. You won’t dread launching or working with Hex Fiend even on low-RAM machines. Open a huge file, scroll around, copy and paste, all instantly. Find what you’re looking for with fast searching. Hex Fiend knows not to waste time overwriting the parts of your files that haven’t changed, and never needs temporary disk space.
Interpret data as integer or floating point, signed or unsigned, big or little endian...
It’s really easy to incorporate Hex Fiend’s hex or data views into your app. Its permissive BSD-style license won’t burden you.