The OpenGL Extension Wrangler Library (GLEW) is a cross-platform open-source C/C++ extension loading library.
GLEW provides efficient run-time mechanisms for determining which OpenGL extensions are supported on the target platform.
OpenGL core and extension functionality is exposed in a single header file.
GLEW has been tested on a variety of operating systems, including Windows, Linux, Mac OS X, FreeBSD, Irix, and Solaris.
FreeGLUT is a free-software/open-source alternative to the OpenGL Utility Toolkit (GLUT) library.
GLUT was originally written by Mark Kilgard to support the sample programs in the second edition OpenGL ‘RedBook’.
Since then, GLUT has been used in a wide variety of practical applications because it is simple, widely available and highly portable.
GLUT (and hence FreeGLUT) takes care of all the system-specific chores required for creating windows, initializing OpenGL contexts, and handling input events, to allow for trully portable OpenGL programs.