Hexpad

Written in C#, Hexpad is a simple utility you can use to open files of any type to study contents via hexadecimal display, as well as to modify the byte values of any offsets.

No setup necessary, besides .NET Framework

The tool's not wrapped in a setup pack, so you can save the downloaded files in any part of the hard drive and double-click the .exe to launch the application. It depends on .NET Framework. On the other hand, it doesn't modify Windows registry settings or create extra files on the disk without your consent.

Old-school interface for hex display

Wrapped up in a classical-looking interface that takes us back to older Windows editions, Hexpad invites you to open files by using the file browser or by dropping the items into the main window.
Multiple windows are supported, so you can drop multiple selected files to open all of them, easily toggle their windows, as well as view all open windows from the menu bar. Plus, you can arrange them in any order in the main frame, or display them cascaded or tiled (horizontally or vertically).

Edit offsets and save file changes

It's possible to double-click any offset to edit its byte value in decimal or hexadecimal format. The status bar reveals the total file size (in bytes) along with the current line, column and offset.
The program also lets you change the number of columns to display, and configure font settings regarding the type, style, size and script. Apart from the fact that you can save modifications to the original file or create a new copy, there are no other noteworthy options available here.

Evaluation and conclusion

It had minimal impact on the computer's performance throughout our tests, consuming low CPU and memory. However, it displayed several error dialogs while we were tinkering with the offsets. We must also take into account that Hexpad hasn't been updated for a long time, and it likely has compatibility issues with newer Windows editions.