The Application Development of a Tertiary Grade Repository and Management System is an application-based system designed to efficiently store, manage, and retrieve student academic records, particularly grades, in a centralized and secure digital environment. The system aims to replace traditional manual and spreadsheet-based grade management processes, which are timeconsuming, prone to errors, and difficult to monitor. The application includes essential features such as user authentication and role-based access control, grade encoding and verification, student record management, automated grade computation, and report generation. By providing a reliable and organized grade repository, the system improves operational efficiency, reduces administrative workload, enhances data accuracy, and supports informed academic decision-making within the College of Computer Studies. Overall, it contributes to a more modern, transparent, and effective academic process. The system was developed using application development tools, including Microsoft Visual Studio 2008, XAMPP Control Panel v3.3.0, and MySQL, to build a user-friendly and functional application. Key features include Class Generation, Class Monitoring, Grade Encoding, Report Generation, and Security Measures. To evaluate the system's performance, the ISO 9126 Software Quality Model was applied, assessing critical quality characteristics such as functionality, reliability, usability, and efficiency.