FactorFi — Decentralized Invoice Factoring

Turn unpaid invoices into instant capital. Settle in USDC on-chain.

Live Demo: https://factor-fi.vercel.app

FactorFi is a DeFi protocol that tokenizes B2B invoices as ERC-721 NFTs and enables on-chain factoring. Sellers mint verified invoices, investors fund them at a discount for real-world yield, and repayments are settled in USDC — bypassing traditional banking delays entirely.

Smart Contract Live Deployment

Network: Ethereum Sepolia Testnet Contract Address: 0x9c800E293EaA50316B104E44E2CE15925C22804E

Architecture (Full-Stack Web3)

API keys are never exposed to the frontend. The React client communicates exclusively through a custom Node.js backend proxy.

┌─────────────────┐       ┌─────────────────┐       ┌─────────────────┐
│ React Frontend  │       │ Node.js Backend │       │  External APIs  │
│ (Vite + Ethers) │──────▶│ (Express Proxy) │──────▶│ Stripe & Pinata │
└────────┬────────┘       └────────┬────────┘       └─────────────────┘
         │                         │
         │ (MetaMask TX)           │ (Resend Email)
         ▼                         ▼
┌─────────────────┐       ┌─────────────────┐
│ Smart Contract  │       │  Corporate      │
│ (Sepolia EVM)   │       │  Buyer Wallet   │
└─────────────────┘       └─────────────────┘

Features

• Invoice Tokenization — Mint verified invoices as immutable ERC-721 NFTs.
• Anti-Double Financing — Smart contract permanently logs Web2 invoice IDs to prevent duplicate minting.
• Secure Backend Proxy — Node.js backend handles Stripe API calls, Pinata IPFS uploads, and Resend emails. The frontend never touches secret keys.
• Two-Step Escrow Settlement — Buyers repay into escrow, investors claim yield separately. Trustless and verifiable.
• Investor Marketplace — Browse, filter, and fund unfunded invoices at a discount.
• Rate Limiting & Input Sanitization — API routes are rate-limited (100 req / 15 min) and all inputs are regex-validated before processing.

Tech Stack

Layer	Technology
Frontend	React 19, TypeScript, Tailwind CSS v4, Ethers.js v6
Backend	Node.js, Express, TypeScript, Resend API
Blockchain	Solidity ^0.8.20, OpenZeppelin (ERC721, SafeERC20, ReentrancyGuard)
Storage & Verification	Pinata (IPFS), Stripe Invoicing API

Getting Started

Prerequisites

• Node.js ≥ 18
• MetaMask browser extension
• A testnet wallet with Sepolia ETH + test USDC

Note: Running locally requires your own STRIPE_SECRET_KEY, PINATA_JWT, and RESEND_API_KEY. If you just want to try the app, use the Live Demo instead.

Installation

git clone https://github.com/Namanjs/FactorFi.git
cd FactorFi

Environment Variables

Frontend (frontend/.env)

Variable	Description
VITE_API_BASE	URL of the backend proxy (default: http://localhost:3001)

Backend (backend/.env)

Variable	Description
STRIPE_SECRET_KEY	Stripe API secret key for invoice verification
PINATA_JWT	Pinata JWT token for IPFS uploads
RESEND_API_KEY	Resend API key for buyer notification emails
FRONTEND_URL	Deployed frontend URL (used for CORS)

Run Locally

You must run both servers simultaneously.

1. Start the Backend Proxy

cd backend
npm install
npm run dev

2. Start the Frontend (In a new terminal)

cd frontend
npm install
npm run dev

The frontend will be available at http://localhost:5173 and the backend will run on http://localhost:3001.

Build for Production

cd frontend
npm run build
npm run preview

Project Structure

├── InvoiceEscrow.sol           # Solidity smart contract
├── DOCUMENTATION.md            # Technical & business docs
├── README.md
│
├── frontend/
│   ├── src/
│   │   ├── components/
│   │   │   ├── ErrorBoundary.tsx   # React error boundary
│   │   │   ├── Navbar.tsx          # Global nav with wallet connection
│   │   │   └── Footer.tsx          # Site footer
│   │   ├── lib/
│   │   │   ├── constants.ts        # Contract addresses & ABIs
│   │   │   └── WalletContext.tsx    # Global wallet state
│   │   ├── pages/
│   │   │   ├── Home.tsx            # Landing page
│   │   │   ├── Borrow.tsx          # Seller — verify & mint invoices
│   │   │   ├── Invest.tsx          # Investor marketplace
│   │   │   ├── Portfolio.tsx       # Portfolio & yield tracking
│   │   │   └── NotFound.tsx        # 404 page
│   │   ├── App.tsx                 # Router + WalletProvider
│   │   └── main.tsx                # Entry point
│   ├── package.json
│   └── vite.config.ts
│
└── backend/
    ├── src/
    │   └── server.ts               # Express API proxy
    └── package.json

Smart Contract

The InvoiceEscrow.sol contract handles:

• mintInvoice() — Seller creates an invoice NFT with face value, discounted price, due date, and buyer wallet address
• fundInvoice() — Investor pays the discounted price in USDC; 1% protocol fee routes to the treasury, 99% goes to the seller
• repayInvoice() — The designated buyer deposits the face value into the smart contract escrow
• claimYield() — The investor withdraws their payout after the buyer has repaid the escrow

Team

Built by Naman Agarwal.

License

MIT