htop - an interactive process viewer

Document viewer

Lightweight image viewer written in C and SDL2

GTKWave is a fully featured GTK+ based wave viewer for Unix and Win32 which reads LXT, LXT2, VZT, FST, and GHW files as well as standard Verilog VCD/EVCD files and allows their viewing.

A minimal terminal hex viewer supporting reading, writing and searching in files and processes.

A lightweight image viewer written entirely in C and OpenGL 3.3

Window Hierarchy and Properties Viewer

Just another image viewer

A simple TXT Reader for the Numworks Calculator [Don't use it for cheating]

A 3D-Viewer for displaying 3D scenes

GPU accelerated, unbiased physically-based renderer for CAD models based on Open CASCADE Technology

Image viewer/editor for RISC OS & desktop application library

an SVG image viewer for plan9

hexamine is a graphical viewer for binary files with autoupdate capabilities

Tutorial for creating a Virtual Machine Viewer on Fedora with Spice-GTK

The minimalistic SQLite editor for non-programmers

Independent ReactOS Clipbrd

a filter program to have a display of a trax game.

E1.31 (sACN) Xterm256 Console Viewer