The research goal of this project is to build a second-hand commodity trading platform. The system is aimed at the campus student user groups. Students can publish second-hand goods, auction, comment and donate through the platform.

The App is developed on Android Studio by using Java. The back-end is deployed on the Firebase database.

I used authentication, Cloud Storage, Realtime Database, Cloud Firestore.

Key features: The user can register, log in, reset password. The user can talk with others by using chatting function. The user can change to a different language at ease. The user can publish, delete the post/auction. The administrator can create a welfare donation event, and the user could apply to donate