Computer aided assessment (CAA) tools are more and more widely adopted in academic environments mixed to other assessment means. In this article, we present a CAA Web application, named eWorkbook, which can be used for evaluating learner's knowledge by creating (the tutor) and taking (the learner) on-line tests based on multiple choice, multiple response and true/false question types. Its use is suitable within the academic environment in a blended learning approach, by providing tutors with an additional assessment tool, and learners with a distance self-assessment means. In the article, the main characteristics of the tool are presented together with a rationale behind them and an outline of the architectural design of the system.