<![CDATA[Chemistry learning, especially in acid-base materials, is often considered difficult to understand because it is abstract and less associated with the context of students' daily lives. In addition, the implementation of Project Based Learning (PjBL) and the integration of local wisdom in chemistry learning at SMA Negeri 2 Percut Sei Tuan has not been carried out optimally. This research aims to develop an e-module of acid-base chemistry materials that is integrated with local wisdom of cassava tapai and based on Project Based Learning (PjBL), as well as to determine its feasibility level. This research uses the Research and Development (R&D) method with a 4D development model which includes the Define, Design, Develop, and Disseminate stages. The research was carried out in the even semester of the 2025/2026 school year by involving 36 students of class XI of science. At the development stage, validation was carried out by two lecturers of Chemistry Education at Medan State University and one chemistry teacher. The results of the validation of material experts obtained an average percentage of 88.25% and the results of the validation of media experts of 90.49%, both of which are included in the very feasible category. At the dissemination stage, the results of students' responses obtained an average percentage of 87.61% with the very good category, while the teacher's responses obtained an average percentage of 93.30% with the very good category. The results of the study showed that the e-modules developed met the criteria were very feasible and received excellent responses from students and teachers. Thus, the chemistry e-module of acid-base material that is integrated with local wisdom of cassava tapai and based on Project Based Learning (PjBL) is suitable for use as supporting teaching materials in chemistry learning. Keywords: e-module, local wisdom, Project Based Learning (PjBL), Acid-base, Tapai]]>
