This application, Reused Value, is based on the iOS platform and provides users with a trading service of buying and selling second-hand goods. Through this application, users can view and search for the latest information anytime and anywhere. It also has the feature of posting, reviewing, updating, and deleting the posted goods. A live chat service also offered in Reused Value, which facilitates easier and faster communication between users. This project used Swift 5.3.3 programming language and Xcode 12.4 development tools, combined with authentication, database, and cloud storage services provided by Firebase, and followed MVC (Model-View-Controller) design pattern.