🛍️ Vouch – The Student Marketplace (Powered by Algorand)

A secure, campus-focused peer-to-peer marketplace with escrow protection and QR-based handoff verification — powered by the Algorand blockchain.

Live Demo Link: campus-commerce-2iauy6v8w-devcode-srishs-projects.vercel.app

📌 Overview

Vouch is a student-only digital marketplace designed to eliminate fraud in campus buying and selling.

Unlike traditional marketplaces, Vouch uses:

• 🔐 Blockchain-backed escrow (Algorand)
• 📱 QR-based physical exchange validation
• ⭐ Trust score & reputation system
• 🏆 Reward economy for active users
• 📊 Admin monitoring & analytics dashboard

The goal is simple:

No scams. No fake payments. No unsafe exchanges.

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🚀 Core Features

1️⃣ Secure Escrow System (Algorand-Based)

Funds are locked in a smart escrow wallet until both buyer and seller confirm the exchange.

✔ Buyer pays → Funds locked on Algorand ✔ QR generated for transaction ✔ Seller scans QR during meetup ✔ Funds released automatically

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2️⃣ QR-Based Transaction Validation

Every transaction generates a unique QR containing:

• Transaction ID
• Escrow reference
• Buyer ID
• Seller ID
• Timestamp

This ensures physical exchange verification before fund release.

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3️⃣ Trust & Reputation Engine

Users earn trust points based on:

• Successful transactions
• Positive ratings
• Account age
• Dispute-free history

Higher trust = Higher visibility.

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4️⃣ Reward Economy

Users earn platform credits for:

• Completing transactions
• Referring students
• Maintaining high trust

Credits can be used for:

• Promoted listings
• Fee discounts

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5️⃣ Admin Dashboard

Admins can:

• Monitor transactions
• View dispute logs
• Track user activity
• Freeze suspicious accounts

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🏗️ System Architecture

flowchart LR
    A[User - Buyer] --> B[Frontend - Next.js]
    C[User - Seller] --> B
    B --> D[Backend APIs]
    D --> E[Escrow Smart Contract]
    E --> F[Algorand Blockchain]
    D --> G[Database]
    D --> H[QR Generator Service]

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🔄 Complete Transaction Flow

sequenceDiagram
    participant Buyer
    participant Frontend
    participant Backend
    participant Escrow
    participant Seller

    Buyer->>Frontend: Select item & Pay
    Frontend->>Backend: Create transaction
    Backend->>Escrow: Lock funds (Algorand)
    Escrow-->>Backend: Escrow ID
    Backend-->>Frontend: Generate QR
    Buyer->>Seller: Meet physically
    Seller->>Frontend: Scan QR
    Frontend->>Backend: Validate QR
    Backend->>Escrow: Release funds
    Escrow-->>Seller: Transfer payment

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💰 Escrow Logic Flowchart

flowchart TD
    A[Buyer Initiates Purchase] --> B[Payment Sent to Escrow]
    B --> C[Escrow Confirms Lock]
    C --> D[Generate Unique QR Code]
    D --> E[Physical Meetup]
    E --> F{QR Valid?}
    F -- Yes --> G[Release Funds to Seller]
    F -- No --> H[Transaction Blocked]

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🧠 Trust Score Calculation Model

flowchart LR
    A[Successful Transactions] --> D[Trust Engine]
    B[Positive Ratings] --> D
    C[Account Age] --> D
    E[Disputes] --> D
    D --> F[Final Trust Score]

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🗂️ Project Structure

Vouch/
│
├── src/
│   ├── components/      # UI Components
│   ├── pages/           # Application Routes
│   ├── api/             # Backend API Routes
│   ├── services/        # Escrow + Blockchain Logic
│   └── utils/           # Helper functions
│
├── docs/                # Diagrams & documentation
├── public/              # Static assets
├── package.json
└── next.config.ts

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🔐 Why Algorand?

Algorand provides:

• ⚡ High-speed finality (~4 seconds)
• 💸 Extremely low transaction fees
• 🔒 Secure smart contracts
• 🌍 Energy-efficient blockchain

This makes it ideal for micro-transactions in a student economy.

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⚙️ Tech Stack

Layer	Technology
Frontend	Next.js + TypeScript
Styling	Tailwind CSS
Backend	API Routes
Blockchain	Algorand
Database	Firestore / NoSQL
QR System	Dynamic QR Generator

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🛡️ Security Model

✔ Escrow-based smart contract logic ✔ QR validation before release ✔ Server-side transaction verification ✔ Admin monitoring ✔ Dispute handling system

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📈 Scalability Design

The system supports scaling by:

• Stateless backend APIs
• Blockchain-based payment handling
• Cloud-hosted database
• Modular microservice-ready structure

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🔮 Future Enhancements

• 📱 Mobile app version
• 🧾 On-chain transaction history viewer
• 🧠 AI fraud detection engine
• 🎓 University email verification integration
• 💳 Native Algorand wallet integration

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🎯 Problem Solved

Campus marketplaces often suffer from:

❌ Fake UPI screenshots ❌ Non-payment after handoff ❌ Anonymous scammers

Vouch eliminates these through blockchain-backed escrow and QR confirmation.

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🏁 Conclusion

Vouch is not just a marketplace.

It is a trust infrastructure for student commerce, built on the reliability of Algorand and modern full-stack architecture.

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💡 Built For

Hackathons • Campus Deployments • Web3 Innovation • Secure Peer Commerce