SitStraight uses the webcam of your computer to determine if you are sitting upright or slouching. If you are slouching you will get an alert to correct your posture.
Your images are never saved on the server. SitStraight only records the coordinates of your head in space so your pictures are not accesible.
It is estimated that 149 million days of work per year are lost because of low back pain. By correcting your posture, you are improving your overall health.
Sitting right is good for your health, but it might not be so intuitive. Make sure to read the guidelines on proper sitting posture.