AutoHotkey is a powerful and easy to use scripting language for desktop automation on Windows.
http://autohotkey.com/
In late 2012, after consultation with the community, AutoHotkey_L became the official branch.
It's source code can be found here: https://github.com/Lexikos/AutoHotkey_L
along with the documentation here: https://github.com/Lexikos/AutoHotkey_L-Docs