This paper describes the design and development of a mobile language lab system called MLab. The MLab system aims to replace the traditional language lab - which typically has a restrictive layout and lacks interaction - with a more user-friendly, low-cost mobile language lab. The target users of MLab are language teachers and students, and the system offers them the freedom to move around and use their own devices at any time and in any place. The MLab system was developed using several web technologies and Application Programming Interface (API) to provide a fast and convenient method of accessing required content. To evaluate the MLab system, a pilot test was conducted with a class of 15 students and their teacher. The results showed high usability rates and generally positive attitudes toward using the system.