This book depicts a prototype application that assists persons with severe motor disabilities communicate using only their eyes. It also represents a proof for a cheaper solution than the commercial assistants. By using smartphones, a user’s eye movement can be used for manipulating a keyboard for writing messages. However, robust eye tracking algorithms and intuitive user interfaces are a challenge considering smartphone’s processing power and small screen. A prototype application was built for Android smartphones. From the several eye tracking algorithms and user interfaces implemented, only the one that seemed best was user tested. The user evaluation was conducted through the online medium and also with supervised users. The results of the user evaluation shows that the prototype application is difficult to use for uninstructed users. The user experience questionnaire shows that all test users were excited about the prototype. Moreover, they believe the prototype could become a product with certain improvements. As a conclusion the prototype demonstrates that cheap solutions can be implemented for communication using only eye movement.