Simple DirectMedia Layer is a cross-platform development library designed to provide low level access to audio, keyboard, mouse, joystick, and graphics hardware via OpenGL and Direct3D. It is used by video playback software, emulators, and popular games including Valve’s award winning catalog and many Humble Bundle games.
SDL officially supports Windows, Mac OS X, Linux, iOS, and Android. Support for other platforms may be found in the source code.
GLFW is an Open Source, multi-platform library for creating windows with OpenGL contexts and receiving input and events. It is easy to integrate into existing applications and does not lay claim to the main loop. GLFW is written in C and has native support for Windows, OS X and many Unix-like systems using the X Window System, such as Linux and FreeBSD.