In order to reduce the passivity of students and enhance their learning experience in large lectures, we developed a browser-based tool called Classroom Interacter to promote classroom interaction. It allows students to use their own mobile devices to participate in the learning process. The main Features of Classroom Interacter include live voting, status setting and question sending. The evaluation results showed that students were satisfied with the usability and felt it was helpful for their study. Although distraction was reported by some students, the system received very positive evaluations. Most students showed their willingness to use Classroom Intracter in the future.