SikuliX automates anything you see on the screen of your desktop computer running Windows, Mac or some Linux/Unix. It uses image recognition powered by OpenCV to identify and control GUI components. This is handy in cases when there is no easy access to a GUI's internals or the source code of the application or web page you want to act on.
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SikuliX is cross-platform and available on the most popular systems (Windows, OSX and Linux).
Pro Simple text recognition
It's free and open source with the source code hosted on GitHub.
Pro Can run in different languages
Allows running scripts in Jypthon (Python) or JRuby (Ruby) and has also an API.