AntTweakBar is a small and easy-to-use C/C++ library that allows programmers to quickly add a light and intuitive GUI into OpenGL or DirectX based graphic programs to interactively tweak them. Program variables can be linked to a graphical control that allows users to modify them. Programmers are not required to design the graphical interface by providing coordinates or by using a visual UI editor. Controls are automatically organized following an optional given hierarchy.