Eye movements in the form of gaze, pupil dilation and blinking rate can give valuable indication for cognitive and neurological mechanics.
Several open source projects exist that give an alternative to commercial software solutions:
- Pygaze is an Python based toolbox for eyetracking: http://www.pygaze.org/
- Haytham is a gaze tracker for the infrared spectrum: https://sourceforge.net/projects/haytham/
- Ogama tracks mouse movement alongside eye movements: http://www.ogama.net/
- Pupil is a free software pack with emphasis on pupil capture : https://github.com/Pupil-Labs/Pupil