Project

Nexus

I built this project for the ETHGlobal HackMoney 2026 Hackaton. The main idea for me was to create a frictionless experience for the merchant and the customer. The merchant only has to import the React component and customize a few parameters. The customer doesn't have to do much, just pay with the supported chain. Fun experience.

ethglobalsoliditytypescriptcctpnext.jssdkpayments

Nexus is a cross-chain payment solution. Merchants accept USDC on any supported chain and settle instantly on the Arc Testnet via Circle CCTP.

Components

Package	Description
`nexuspay-react`	Core React SDK, drop-in `<NexusPayment />` component
`ethglobal-shop`	Demo store (Next.js + wagmi) showing merchant integration
`merchant-dashboard`	Admin UI for transaction history, withdrawals, and earnings
`foundry`	Smart contracts: `NexusVault` + `NexusPayRelay`

How it works

The <NexusPayment /> component handles the full payment flow client-side:

User connects wallet on any supported chain (Ethereum Sepolia, Base Sepolia, Arbitrum Sepolia, Arc Testnet).
Approves USDC spend.
SDK submits a CCTP transfer; Circle burns USDC on the source chain and mints on Arc.
NexusPayRelay.sol relays the settlement and NexusVault.sol credits the merchant.

<NexusPayment
  merchantAddress={process.env.NEXT_PUBLIC_MERCHANT_ADDRESS}
  amount={1000000n}  // 1 USDC in atomic units
  mode="fixed"
  orderId="ORDER-123"
  onSuccess={(tx, amount) => console.log('Paid!', tx)}
/>

Referral system

Built-in on-chain referral splits. Merchants create campaigns with a reward percentage; affiliates share links with ?campaign=1&ref=0x.... The smart contract splits every payment automatically, no off-chain accounting needed.

Deployed contracts (Arc Testnet)

Stack

Solidity · Foundry · Circle CCTP · Next.js · wagmi · viem · Tailwind CSS

Repository → Live →