This study investigates the effectiveness of the Buana Online Course (BOC) web-based mobile application in enhancing English for specific purposes (ESP) skills among engineering students and explores their perceptions of the course's effectiveness in improving their language proficiency and comprehension of technical texts. The BOC is a learning management system developed by Universitas Buana Perjuangan Karawang Indonesia, and the study involved 49 industrial engineering students from the university. A quantitative research design was employed, with data collected via questionnaires and analyzed descriptively to assess the responses. The findings indicate that the BOC is effective in teaching ESP, with a 49% improvement in reading skills, a 38.80% improvement in writing skills, a 38.80% improvement in communication skills, a 40.80% improvement in applying language skills in an engineering context, and a 38.80% improvement in communication skills. A total of 40.80% of the students showed that the BOC learning management system could be one of the learning media that increases understanding of the cross-cultural aspects among engineering students. The implications of this study suggest that online courses and web-based applications can play a significant role in facilitating ESP learning in engineering contexts and provides valuable insights for educators and institutions aiming to enhance language education through technological integration.