TISB Swap is a community-driven marketplace application designed specifically for the students and faculty of The International School Bangalore (TISB). The project aims to promote sustainability and a circular economy within the school community by facilitating the swapping and resale of pre-owned items. I don't have a runnable link as this is a mobile application that I haven't published to the internet but for the live demo, I have this app which is running on an actually phone. The link for the demo video is: https://vimeo.com/1162593743?share=copy&fl=sv&fe=ci.

The application provides a secure platform for users to list items they no longer need, browse for items listed by others, and communicate directly within the app to arrange swaps or purchases. By encouraging reuse, TISB Swap helps reduce waste and the environmental footprint of the school community.

Reduces Waste: Prevents usable school supplies from ending up in landfills.

Builds Community: Facilitates face-to-face interactions between seniors and juniors.

Promotes Honesty: A transparent Lost & Found hub encourages pro-social behavior.

Gamifies Impact: Real-time CO2 and Tree-saving metrics motivate students to participate.

This proejct as you can tell falls under the sustaniblity theme. But it could also be consided as technology for social good.

• Marketplace: A central feed where users can browse listed items across various categories.
• Item Listing: Easy-to-use form for users to list their items with descriptions, categories, and images.
• Real-time Chat: Integrated messaging system for users to communicate and coordinate swaps.
• Lost and Found: A dedicated section for reporting and finding lost items within the school campus.
• Sustainability Tracking: Impact badges and statistics that highlight the environmental benefits of swapping items (e.g., CO2 saved, water conserved).
• User Profiles: Personalized profiles managing user listings, active chats, and sustainability stats.
• Secure Authentication: User verification and account management powered by Supabase. Only users with a TISB email domain (@tisb.ac.in) can enter this ecosystem.
• Spam and Scam detection: Users can report scam. There are also auto triggering features like banning with occur after a user uploads more than 5 items to the marketplace in a month. This is only temerary as they can still do everything else. Also after 5 reports, the sender gets baned so they cant upload more items to the marketplace until further inspection.
• Live counter: Shows the collective impact of the community on the enveronment. This is visible on the welcome screen.
• Realtime backend: I am using supabase to make sure that all the data is managed properly. It allows for most of the features mentioned above. It also allowed for proper security using RLS polices.

• Frontend: Flutter (Dart)
• Backend: Supabase (Authentication, Database, and Storage)
• State Management: Provider / Flutter built-in mechanisms
• Theme: Material 3 with Google Fonts (Inter), and system fonts. For the colors I went with a green coor pallet to show the eco friendly aim of this application.
• Logic/Utilities: flutter_dotenv for environment management, image_picker for media handling, and intl for formatting.

The codebase follows a modular and clean architecture, ensuring scalability and maintainability for the future if I decide to deploy this in the future

• main.dart: The entry point of the application. It handles the initialization of Supabase, environment variables, and defines the global theme and routing.
• models/: Contains data models that define the structure of the application's data.
  • item.dart: Represents a marketplace or lost/found item.
  • message.dart: Defines the structure for chat messages.
  • user_profile.dart: Manages user-related data and statistics.
• screens/: Contains the full-page UI components.
  • welcome_screen.dart: The initial onboarding and login page.
  • marketplace_screen.dart: The main item discovery feed.
  • item_details_screen.dart: Detailed view of a specific item.
  • list_item_screen.dart: Interface for creating new listings.
  • chat_list_screen.dart: Overview of all active conversations.
  • chat_screen.dart: Individual messaging interface.
  • lost_found_screen.dart: Feed for lost and found items.
  • profile_screen.dart: User settings and activity hub.
  • report_item_screen.dart: Utility for reporting problematic content or items.
• services/: Contains logic for external communications.
  • supabase_service.dart: A centralized service handling all interactions with Supabase, including database queries, authentication requests, and file uploads.
• utils/: Includes helper classes and constants.
  • colors.dart: Defines the application's color palette (e.g., primary greens, grays).
  • constants.dart: Stores layout constants, text styles, and reusable configuration values.
• widgets/: Contains reusable UI components used across multiple screens.
  • item_card.dart: The preview card for marketplace listings.
  • lost_found_card.dart: Specialized card for lost/found items.
  • custom_button.dart: Standardized button component.
  • impact_badge.dart: Visual indicator for environmental impact.
  • stat_card.dart: Displays user metrics on the profile page.
  • category_chip.dart: Interactive filters for browsing items.

During this hackathon, I significantly deepened my expertise in relational databases, security protocols, and native mobile configurations. While the experience was rewarding, it wasn't without its hurdles—most notably the steep learning curve of Supabase.

Configuring the database and mastering Row-Level Security (RLS) policies was a major technical challenge, as I had to ensure that user data remained strictly private and secure at the database level. Additionally, the UI proved demanding; I had to architect and code a high volume of screens in a very short window, ensuring each one was not only functional but also maintained a seamless UX.

This project was developed for the TISB Hacks 2026 competition. All code is structured to facilitate collaborative development and future feature expansions. This is a solo project by me (Ayansh Paliwal)