One important issue in modern database applications is supporting the user with efficient tools to debug and fix queries because such tasks are both time and skill demanding. One particular problem is known as Why-Not question and focusses on the reasons for missing tuples from query results. The EFQ platform demonstrated here has been designed in this context to efficiently leverage Why-Not Answers polynomials, a novel approach that provides the user with complete explanations to Why-Not questions and allows for automatic, relevant query refinements.