ChainFair is a blockchain-based DApp that addresses economic information asymmetry in agricultural supply chains. Consumers scan QR codes on produce to instantly reveal the full supply chain profit split, educating users on fair trade economics and empowering small farmers.
- Farmer Share: Indian farmers receive only 10-15% of consumer price vs 40-60% in developed nations
- Middlemen Dominance: 3-4 intermediaries each take 15-30% margin
- Lack of Transparency: No way for consumers to verify fair trade claims
- Education Gap: 73% of urban consumers unaware of farmer income challenges
"The biggest challenge facing Indian farmers is not production, but fair price discovery and market access." - NITI Aayog Agricultural Report 2023
ChainFair provides:
- Immutable Profit Records - Blockchain-verified supply chain data
- Consumer Education - Visual breakdown of where money goes
- Farmer Empowerment - Transparent pricing builds trust
- QR-Based Access - Mobile-first, no internet required for basic access
| Layer | Technology | Purpose |
|---|---|---|
| Blockchain | Solidity + Polygon Mumbai | Low-cost smart contracts (<$0.01/tx) |
| Storage | IPFS (Pinata) | Decentralized image/cert storage |
| Mobile | React Native (Expo) | Cross-platform QR scanner app |
| Dashboard | Next.js | Admin portal for farmers/retailers |
| Wallet | ethers.js + MetaMask | Web3 integration |
| Charts | Recharts | Profit visualization |
chainfair/
├── contracts/
│ └── SupplyChain.sol # Smart contract
├── scripts/
│ └── deploy.js # Deployment script
├── test/
│ └── SupplyChain.js # Contract tests
├── frontend/app/
│ ├── App.js # React Native app
│ └── package.json
├── dashboard/
│ ├── src/pages/index.js # Admin dashboard
│ └── package.json
├── .env.example
├── hardhat.config.js
└── README.md
- Node.js 18+
- npm or yarn
- MetaMask browser extension
- Git
git clone https://github.com/spike-commander/chainfair.git
cd chainfair
npm install# Copy environment file
cp .env.example .env
# Edit .env with your values:
# POLYGON_MUMBAI_RPC=https://rpc-mumbai.maticvigil.com
# PRIVATE_KEY=your_private_key
# POLYGONSCAN_API_KEY=your_api_key
# Compile contracts
npm run compile
# Run local tests
npm run test
# Start local node
npm run node
# Deploy to local (separate terminal)
npm run deploy:local
# Deploy to Mumbai testnet
npm run deploy:mumbaicd frontend/app
npm install
npm startScan QR code with Expo Go app or run on iOS/Android simulator.
cd dashboard
npm install
npm run devThe deployment script creates 3 demo supply chains:
| Product | Farmer Price | Consumer Price | Farmer Share |
|---|---|---|---|
| Jabalpur Alphonso Mango | ₹20 | ₹200 | 10% |
| Jabalpur Organic Tomato | ₹15 | ₹150 | 10% |
| Kashmir Premium Apple | ₹50 | ₹300 | 17% |
// Create new supply chain
createChain(string productName, string origin, uint256 farmerPrice, string ipfsHash, string certificationHash) returns uint256 tokenId
// Add stage to existing chain
addStage(uint256 tokenId, StageType stageType, string actorName, uint256 profitShareBPS, uint256 priceAtStage, string ipfsHash, string certificationHash) returns uint256 stageIndex
// Complete chain
completeChain(uint256 tokenId)
// Query chain data
getChain(uint256 tokenId) returns (productName, origin, totalPrice, farmerPrice, stageCount, isComplete, createdAt)
// Get profit split
getChainProfitSplit(uint256 tokenId) returns (profitShares[], stageNames[], totalPrice)event ChainCreated(uint256 indexed tokenId, string productName, string origin, uint256 farmerPrice);
event StageAdded(uint256 indexed tokenId, StageType stageType, address actor, uint256 profitShareBPS, uint256 priceAtStage);
event ChainCompleted(uint256 indexed tokenId, uint256 totalPrice);- QR code scanning using device camera
- Real-time blockchain data fetching
- Pie chart profit breakdown visualization
- Multilingual support (English/Hindi)
- Demo mode with pre-loaded data
- Educational insights about fair trade
- Supply chain creation interface
- Stage addition workflow
- IPFS file upload for certifications
- Analytics and metrics visualization
- Farmer/retailer authorization
- Gas-optimized (<10K gas per transaction)
- ERC-20 compatible profit shares (BPS)
- Role-based access control
- Event-driven architecture
| Criteria | ChainFair Implementation |
|---|---|
| Relevancy | Addresses agri economics, blockchain code, consumer education |
| Technical Execution | Solidity + Polygon + IPFS + React Native |
| Impact | Direct benefit to MSME farmers, consumer awareness |
| Presentation | Demo video ready, pitch deck included |
| Innovation | Novel QR-blockchain bridge for rural India |
Images and certifications are stored on IPFS to avoid blockchain bloat:
// Upload to IPFS
const ipfsHash = await ipfs.add(imageBuffer);
const gatewayUrl = `https://ipfs.io/ipfs/${ipfsHash}`;
// Store only hash on chain
await contract.createChain(productName, origin, price, ipfsHash, certHash);- Packed structs for storage efficiency
- Events instead of storage for historical data
- Batch operations where possible
- Estimated cost: ~8-10K gas per stage addition
# Blockchain
POLYGON_MUMBAI_RPC=https://rpc-mumbai.maticvigil.com
PRIVATE_KEY=0x...
# Verification
POLYGONSCAN_API_KEY=your_key
# Frontend
NEXT_PUBLIC_CONTRACT_ADDRESS=0x...
# IPFS
IPFS_PROJECT_ID=your_id
IPFS_API_KEY=your_key- Fork the repository
- Create feature branch (
git checkout -b feature/amazing-feature) - Commit changes (
git commit -m 'Add amazing feature') - Push to branch (
git push origin feature/amazing-feature) - Open Pull Request
MIT License - See LICENSE file
- Chainlink Supply Chain Documentation
- MDPI Blockchain in Agriculture Papers
- Polygon Developer Documentation
- OpenZeppelin Smart Contract Library
- Project Link: https://github.com/spike-commander/chainfair
- Discord: Join our community
- Email: abdulhaiy1502@gmail.com
Built for Hackathonomics 2026 - Empowering agricultural transparency through blockchain