Pertumbuhan usaha properti sewa khususnya rumah kos di kota-kota besar Indonesia mendorong kebutuhan akan sistem pengelolaan yang lebih efisien. Permasalahan yang dihadapi pemilik kos di daerah Badung meliputi pencatatan data penghuni secara manual, monitoring masa sewa yang tidak terpantau, ketidakakuratan pencatatan pembayaran, dan tidak adanya laporan keuangan yang komprehensif. Penelitian ini bertujuan merancang aplikasi manajemen kos berbasis web menggunakan metode System Development Life Cycle (SDLC) Agile Development dengan pendekatan Object-Oriented Analysis and Design (OOAD). Data dikumpulkan melalui wawancara semi-terstruktur, kemudian dianalisis menggunakan teknik mapping untuk merumuskan kebutuhan sistem. Hasil penelitian menghasilkan artefak OOAD yang komprehensif meliputi use case diagram, activity diagram, sequence diagram, dan class diagram, serta perencanaan enam sprint Agile. Aplikasi dirancang dengan sepuluh kebutuhan fungsional dan lima kebutuhan non-fungsional yang mencakup manajemen data penghuni, pencatatan pembayaran, notifikasi jatuh tempo otomatis, pencatatan biaya maintenance, dan pelaporan keuangan real-time. Pengujian black box testing terhadap seluruh modul menunjukkan hasil yang valid. Penelitian ini menyimpulkan bahwa aplikasi yang dirancang berpotensi meningkatkan efisiensi pengelolaan penghuni dan keuangan secara signifikan, mengurangi potensi kesalahan pencatatan, serta memberikan visibilitas kondisi usaha yang lebih baik bagi pemilik kos.
The growth of rental property businesses, particularly boarding houses (kos), in major Indonesian cities has driven the need for more efficient management systems. Problems faced by boarding house owners in the Badung area include manual tenant data recording, unmonitored lease period tracking, inaccurate payment records, and the absence of comprehensive financial reporting. This study aims to design a web-based boarding house management application using the System Development Life Cycle (SDLC) Agile Development method with an Object-Oriented Analysis and Design (OOAD) approach. Data were collected through semi-structured interviews with a boarding house owner managing 24 rooms, then analyzed using a mapping technique to formulate system requirements. The research produced comprehensive OOAD artifacts including use case diagrams, activity diagrams, sequence diagrams, and class diagrams, along with a six-sprint Agile development plan. The application was designed with ten functional requirements and five non-functional requirements covering tenant data management, payment recording, automatic due date notifications, maintenance cost tracking, and real-time financial reporting. Black box testing across all modules yielded valid results. This study concludes that the designed application has the potential to significantly improve tenant and financial management efficiency, reduce recording errors, and provide better business visibility for boarding house owners.