Bless is described as 'High quality, full featured hex editor. It is written in mono/Gtk# and its primary platform is GNU/Linux. However it should be able to run without problems on every platform that mono and Gtk# run on' and is an app in the development category. There are more than 25 alternatives to Bless for a variety of platforms, including Windows, Linux, Mac, BSD and PortableApps.com apps. The best Bless alternative is ImHex, which is both free and Open Source. Other great apps like Bless are HxD, UltraEdit, wxHexEditor and 010 Editor.
Hexer is an open-source hex editor for Windows featuring direct view of all kinds of data interpretations, and in-line data type annotation system with markers which is reusable across files.
HextEdit is a fast and lightweight hex editor for viewing and editing binary data. Quickly edit virtually any file type at a low level in a simple and native app. It features fast incremental find, a byte inspector and generally fast performance as a native app.
Tweak is a hex editor. It allows you to edit a file at very low level, letting you see the full and exact binary contents of the file. It can be useful for modifying binary files such as executables, editing disk or CD images, debugging programs that generate binary file formats...
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