In this paper, a customized multi-language development environment (MLDE), PolyLAB, is developed for students in Nigerian Polytechnics. The online programming laboratory supports the entire Nine (9) programming languages offered by computer science students in Nigeria Polytechnic at both National Diploma (ND) and Higher National Diploma (HND); namely Java, Python, C, C++, MATLAB, PASCAL, HTML, CSS and JavaScript. Using the content management system of PolyLAB, Lecturers and Technologist in Nigeria Polytechnics can post lesson materials on programming courses taught by them for their students to study while the integrated multi-language code editor will allow the student to try program codes on the fly. Successful implementation of PolyLAB will remove the burden of both the technicalities and the cost of both setting up and maintaining different development environments used by Computer Science students in Nigerian Polytechnics, as well as facilitate independent studies from individual comfort locations.