This study aimed to design and implement a focused web-based Learning Management System (LMS) for pre-university learning at UPN "Veteran" Jawa Timur. The research gap addressed in this study is the limited suitability of general LMS or commercial e-course platforms for the transitional learning needs of high-school students who require structured exposure to university-level learning before entering higher education. At the same time, institutions need an integrated platform that can manage learning activities, user roles, course administration, and supporting academic transactions in one environment. Unlike conventional LMS platforms that are mainly designed for enrolled university students, the proposed system combines course discovery, self-paced learning, assessment, discussion, progress monitoring, certificates, payment, and role-based administration within a single institutional platform. The system was developed using Rapid Application Development (RAD), which supports rapid prototyping, user feedback, and iterative refinement during system development. The application was implemented using Next.js for the frontend, Laravel as a RESTful API backend, and PostgreSQL as the relational database. Evaluation was conducted through black box testing of representative functional workflows and User Acceptance Testing involving five students, two instructors, and one administrator. The black box testing showed that the selected functional modules operated according to the expected results. The UAT results showed student acceptance of 94%, instructor acceptance of 87%, and administrator acceptance of 86%. These findings provide preliminary evidence of functional readiness and role-based user acceptance, while broader learning effectiveness, scalability, security, and institutional feasibility require further evaluation.