BarterBrAIn

Tagline: Barter Better with BarterBrAIn.BarterBrAIn is a smart marketplace app that lets students easily swap what they don’t need for what they do. Make sustainable choices for planet and wallet.

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BarterBrAIn

A campus-only AI powered barter marketplace for sustainable, affordable student living

The Problem

Every semester on campus, we watched the same thing happen. Students moving out left perfectly good lamps, fans, chairs, kettles, shelves, and textbooks piled beside dumpsters. A week later, new students arrived and bought the exact same items at full price.

It felt backwards. It was expensive for students. It was wasteful for the environment. And it created frustration every move-in season.

One afternoon we looked at each other and asked: _“Why isn’t there a safe, campus-verified, modern barter system where students can simply swap items?” _

That question became the seed for BarterBrAIn: A smarter way to exchange what you no longer need for what you actually want, guided by AI to keep trades fair, fast, and friendly.

🌱 Inspiration

Barter culture exists everywhere, but on campus it never works smoothly. People don’t know how to negotiate. Values are unclear. Trust is low. And most platforms are built for buying or selling, not swapping.

We wanted to fix three things:

Waste — too many usable items ended up in landfills.

High costs — essential living items aren’t cheap.

Awkward negotiation — students often hesitate to barter.

We believed that with AI and a thoughtful user experience, swapping could feel natural and even fun.

🎯 What BarterBrAIn Does

BarterBrAIn is a full stack, campus-verified, AI assisted barter marketplace where students can:

✔ Swap items with peers ✔ Chat and negotiate in real time ✔ Get AI suggestions that keep trades fair ✔ Estimate item value using Gemini ✔ Pay or receive difference through Capital One Nessie ✔ Track CO₂ and money saved after every completed swap ✔ Stay safe with .edu authentication

It turns the chaotic swap experience into something simple, safe, and sustainable.

🧠 How We Built It

We built BarterBrAIn from scratch as a complete, production-style system that ties together mobile apps, real time messaging, AI scoring, pricing logic, and financial transactions.

Frontend

Flutter

Cross-platform mobile app

GetX for reactive state management

MVC inspired architecture

Clean liquid-glass UI for clarity in item comparison

Real time multi-screen updates for negotiations and item changes

Backend

Firebase

Authentication with .edu verification

Firestore for real time trade and chat data

Cloud Storage for item images

Cloud Functions (Node.js with Express) for AI pipelines, negotiation logic, and pricing workflows

AI Features

Gemini 2.5 Flash

Real time chat analysis and negotiation strategy

Value estimation for items with incomplete details

Sustainability impact estimation (CO₂ saved and money saved)

Prompt-engineered decision logic that adapts to conversation flow

Tech stack for AI:

Firebase Cloud Functions (Node.js / Express)

Gemini 2.5 Flash multimodal

Realtime context injection from Firestore and FCM

Payments

Capital One Nessie API

Used to simulate secure exchange of price differences

Supports completion of trades when an item’s value difference must be settled

Integrated cleanly into the barter flow instead of treating payments as a separate operation

Key AI Features

AI Negotiation Coach

Negotiating is the heart of bartering, but most students don’t feel confident doing it. Our AI coach steps in only when asked, analyzing:

Live chat transcript

Item conditions and descriptions

Estimated values

Tone and trajectory of the negotiation

Current offer and cash adjustment

It then suggests:

A friendly message to send

A fair cash adjustment

A short rationale

A few closing tips for sealing the deal

This keeps negotiation stress-free while preserving the authenticity of human-to-human trade.

Sustainability Impact

After each completed swap, the app calculates:

CO2_saved = CO2_new_item − CO2_swapped

Money_saved = Cost_new − Cost_swap

Gemini generates a human readable summary like: “You saved 82 kg CO₂ and $55 by swapping instead of buying new.”

This makes sustainability feel personal and measurable, not abstract.

Challenges We Ran Into

This project pushed us harder than expected. Our biggest challenges were:

Designing real time AI negotiation that could follow chat flow naturally

Ensuring fair price estimation even when item details were incomplete

Creating a clean dual-platform mobile UI within tight hackathon time

Integrating Capital One Nessie inside a barter based transaction flow

Keeping multi-screen data consistent using GetX’s reactive state

Reducing AI latency across multiple Cloud Functions and API calls

Every challenge forced architectural refinements, smarter caching, and UI polish under intense deadlines.

Accomplishments We’re Proud Of

Built a fully functioning barter marketplace from scratch in a weekend

Delivered a real time negotiation AI that adapts to conversation context

Integrated a fintech workflow into a swap-based model

Built a polished mobile front end with synchronized chat, valuation, and item screens

Created sustainability impact summaries that genuinely motivate users

Shipped a clean, stable MVP that feels like a real product, not a prototype

What We Learned

This project taught us how to blend AI, fintech, and mobile systems into one seamless user experience. We learned:

How to architect AI features that feel helpful instead of overwhelming

How to manage real time negotiation data across multiple users and screens

How Gemini’s reasoning can be adapted to valuation and conversation context

How to build trustworthy financial operations with Nessie

How good UI design makes or breaks a marketplace experience

Why BarterBrAIn Matters

Bartering isn’t new. But making it safe, fair, and guided by modern AI creates something powerful.

Students save money. Campuses reduce waste. Negotiation becomes accessible. Financial literacy improves. AI becomes a mentor, not a mystery.

BarterBrAIn isn’t just a marketplace. It’s a step toward circular economies inside student communities.

What’s Next

We’re excited to expand BarterBrAIn with:

AI based item categorization

Multi-campus onboarding

A sustainability score for each user

Personalized item recommendations

Event based swap drives during move-in and move-out weeks

Built With

  • capital-one-hackathon-api
  • express.js
  • firebase
  • firebase-console)-cloud-services:-google-cloud-(via-firebase)
  • firebase-functions
  • firebase-functions-http-endpoints-mobile:-flutter-(for-the-mobile-app
  • firebase-hosting
  • flutter
  • gemini-flash-2.5pro
  • gemini-multimodel-api
  • git
  • google-gemini-api-(generative-ai)-apis:-google-generative-ai-(gemini)
  • google-generative-ai-(gemini)
  • handled-by-prithvi)-version-control:-git
  • javascript
  • node.js
  • rest-api
  • vs-code
  • xcode
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