A multi-platform library for OpenGL, window and input
GLFW is a free, Open Source, multi-platform library for opening a window, creating an OpenGL context and managing input. It is easy to integrate into existing applications and does not lay claim to the main loop.
This is the documentation for version 3.0, which has many new features.
There is a quick tutorial for people new to GLFW, which shows how to write a small but complete program.
If you have used GLFW 2.x in the past, there is a transition guide that explains what has changed and how to update existing code to use the new API.
As this is still unfinished software, there are still a number of bugs.