hex editor

Noun

hex editor (plural hex editors)

1. (computing) A text editor that allows for manipulation of the fundamental binary data that constitutes a computer file, displayed in hexadecimal format.
   • 2000 September 18, Maddox (George Ouzounian), I hate Solitaire.‎, retrieved September 19, 2016:

     The only good thing about Solitaire is being able to ruin it with a hex editor so nobody else can play it.

Further reading

• hex editor on Wikipedia.Wikipedia