ArcPay

Cross-border stablecoin invoice and payment platform built on Arc Network.

Businesses create invoices denominated in USDC or EURC and share a payment link. Payers settle on-chain in three steps — connect wallet, approve tokens, fund escrow — with no intermediaries and sub-second finality.

Live app: arc-network-research.replit.app

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Features

• Invoice creation — title, amount, currency (USDC/EURC), recipient address, due date, optional privacy mode
• Shareable pay links — /pay/:id checkout page with guided 3-step on-chain flow and live transaction links
• Escrow settlement — approve → fundEscrow → releaseEscrow with configurable dispute window
• Invoice NFT — each paid invoice mints an ERC-721 receipt to the payer's wallet
• Privacy mode — amount hidden on the public pay page; stored off-chain only
• PDF export — download any invoice as a formatted PDF, in-browser
• Analytics dashboard — volume charts, currency split, payment status breakdown (Recharts)
• Protocol revenue tracker — live on-chain FeeCollected event feed from ArcScan
• CCTP cross-chain payments — payers on Ethereum, Avalanche, or Base can pay via Circle's Cross-Chain Transfer Protocol
• Mainnet readiness checklist — interactive pre-flight page at /mainnet with live RPC check and copyable deploy commands

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Smart Contracts

Written in Solidity 0.8.20, deployed with Hardhat. No external oracle or bridge dependency for the core payment flow.

Architecture

Payer
  │
  ├─ ERC-20.approve(PaymentEscrow, amount)
  ├─ PaymentEscrow.fundEscrow(invoiceId)   ← pulls tokens, holds in escrow
  └─ PaymentEscrow.releaseEscrow(id)       ← sends net to payee, fee to treasury, calls markPaid
                                                │
                                         InvoiceRegistry.markPaid(id)
                                         InvoiceNFT.mint(payer)

• InvoiceRegistry — stores invoice metadata, enforces state machine (Pending → Paid/Cancelled)
• PaymentEscrow — holds funds, deducts 30 bps protocol fee on release, emits FeeCollected
• InvoiceNFT — ERC-721 receipt minted to payer on settlement
• Protocol fee — 30 bps (0.30%), configurable by owner via setFee(feeTo, feeBps), hard-capped at 500 bps

Deployed Contracts

Arc Network Testnet (chain ID 5042002)

Contract	Address
InvoiceRegistry	0x64D160b7E91e78e52dFc0e8829640E32A919164C
PaymentEscrow v3	0xAc6F84B255910D95efC4E90D6f1dd5A3e7FCe7e2
InvoiceNFT	0x6F80056564491425273A6a481EcC5DAea9D57f23
USDC	0x3600000000000000000000000000000000000000 (native system contract)
EURC	0x89B50855Aa3bE2F677cD6303Cec089B5F319D72a

Explorer: testnet.arcscan.app
Faucet: faucet.circle.com — select Arc Testnet (20 USDC / 2 hrs)

Ethereum Sepolia Testnet (chain ID 11155111)

Contract	Address
InvoiceRegistry	0xa77710C5d06A829809b8149C602C71654a9F40bD
PaymentEscrow	0xC45A6938Fd656Ed48021A6C611396BF18b3C8EaA
InvoiceNFT	0x1e7e5166029e287ca6264456b88d200d1118289D
USDC	0x1c7D4B196Cb0C7B01d743Fbc6116a902379C7238 (Circle)
EURC	0x08210F9170F89Ab7658F0B5E3fF39b0E03C594D4 (Circle)

Arc Network Mainnet (chain ID 4564) — pending Arc launch

Contracts will be deployed when Arc Mainnet is live. See the Mainnet Readiness page in the app for the pre-flight checklist.

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Stack

Layer	Technology
Frontend	React 19, Vite 7, Tailwind CSS v4, Wouter, TanStack Query
On-chain	viem 2.x, MetaMask / EIP-1193
API	Express 5, Node.js 24
Database	PostgreSQL, Drizzle ORM
Validation	Zod v4, drizzle-zod
Contracts	Hardhat 2.28, Solidity 0.8.20, ethers v6
Charts	Recharts
PDF	jsPDF
Monorepo	pnpm workspaces, TypeScript 5.9
API codegen	Orval (OpenAPI → React Query hooks + Zod schemas)

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Project Structure

├── artifacts/
│   ├── arcpay/          # React + Vite frontend
│   └── api-server/      # Express API
├── contracts/
│   ├── src/             # Solidity contracts
│   │   ├── InvoiceRegistry.sol
│   │   ├── PaymentEscrow.sol
│   │   └── InvoiceNFT.sol
│   ├── scripts/
│   │   └── deploy.ts    # Hardhat deploy script
│   └── deployments/     # Generated address files per network
├── lib/
│   ├── contract-abis/   # TypeScript ABI constants (@workspace/contract-abis)
│   ├── db/              # Drizzle schema + migrations
│   └── api-spec/        # OpenAPI spec + codegen
└── DEPLOYMENT.md        # Full deploy guide

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Local Development

Requirements

• Node.js 24+
• pnpm 9+
• PostgreSQL (or use the Replit-managed database)
• MetaMask browser extension

Setup

# Clone and install
git clone <repo-url>
cd arcpay
pnpm install

# Set environment variables (copy and fill in)
cp artifacts/arcpay/.env.example artifacts/arcpay/.env.local
# Required: DATABASE_URL, VITE_CHAIN_ID, contract addresses

# Push database schema
pnpm --filter @workspace/db run push

# Start the API server (port 8080)
pnpm --filter @workspace/api-server run dev

# Start the frontend (port from $PORT)
pnpm --filter @workspace/arcpay run dev

Compile and deploy contracts locally

cd contracts
pnpm install

# Compile
pnpm run compile

# Start a local Hardhat node
pnpm run node

# Deploy to local node (new terminal)
pnpm run deploy:local

# Copy addresses to frontend
cp deployments/localhost.env ../artifacts/arcpay/.env.local

Deploy to Arc Testnet

cd contracts

# Set your deployer key in contracts/.env
echo "DEPLOYER_PRIVATE_KEY=0x..." > .env

pnpm run deploy:arc
cp deployments/arc.env ../artifacts/arcpay/.env.local

See DEPLOYMENT.md for the complete guide including mainnet deployment, contract verification on ArcScan, and fee management.

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Environment Variables

Frontend (artifacts/arcpay/.env.local):

VITE_CHAIN_ID=5042002
VITE_INVOICE_REGISTRY_ADDRESS=0x...
VITE_PAYMENT_ESCROW_ADDRESS=0x...
VITE_INVOICE_NFT_ADDRESS=0x...
VITE_USDC_ADDRESS=0x...
VITE_EURC_ADDRESS=0x...

API server:

DATABASE_URL=postgresql://...
SESSION_SECRET=...

Contracts (contracts/.env):

DEPLOYER_PRIVATE_KEY=0x...
# For mainnet only:
ARC_MAINNET_USDC_ADDRESS=0x...
ARC_MAINNET_EURC_ADDRESS=0x...

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Contract Ownership & Revenue

• Owner — the wallet that ran the deploy script. Can call setFee() and transferOwnership() on PaymentEscrow, and setAuthorizedEscrow() on InvoiceRegistry.
• Protocol fee — 30 bps (0.30%) of each payment, sent to feeTo on releaseEscrow. Defaults to the deployer wallet; update with setFee(newTreasury, 30) to point to a multisig.
• Fee cap — hard-coded at 500 bps (5%) in the contract; cannot be exceeded regardless of what the owner sets.

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Payment Flow (on-chain)

1. Payer visits /pay/:invoiceId — fetches invoice metadata from API
2. Connect wallet — MetaMask prompt, switches to Arc Network automatically
3. Approve — USDC.approve(PaymentEscrow, amount) — one MetaMask tx
4. Fund escrow — PaymentEscrow.fundEscrow(invoiceId) — pulls USDC into contract
5. Release — PaymentEscrow.releaseEscrow(escrowId) — sends net to payee, fee to treasury, mints NFT receipt, marks invoice paid

Steps 4 and 5 can be merged into instant settlement by setting releaseDelay = 0 (current default).

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Links

Resource	URL
Live app	https://arc-network-research.replit.app
Arc Testnet Explorer	https://testnet.arcscan.app
Arc Mainnet Explorer	https://arcscan.app
Arc Documentation	https://docs.arc.network
Circle USDC Faucet	https://faucet.circle.com
Circle CCTP Docs	https://developers.circle.com/stablecoins/docs/cctp-getting-started

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License

MIT