LinkPay

LinkPay - Automated Cross-Chain Payroll System

URLs / Links:

• dApp: https://linkpay-seven.vercel.app/ 
• Smart Contract (Wormhole CCTP): 0xe7335Ee6af0bE5288daeC898Cf74D51D3eE92A2e (Base Sepolia)
• Link: https://sepolia.basescan.org/address/0xe7335Ee6af0bE5288daeC898Cf74D51D3eE92A2e#code 
• Smart Contract (Legacy Chainlink CCIP): 0x291AB221FB0E8C8EEE246E9476Bb2E892D82DcaB (Base Sepolia)
• Link: https://sepolia.basescan.org/address/0x291AB221FB0E8C8EEE246E9476Bb2E892D82DcaB#code 
• Wormhole TX: https://sepolia.basescan.org/tx/0x69cba37a4084966e5a37fa0e6335be1894710b3f56427d18e7a28dd5e13ef9c3
• Smart Contract (Scroll): 0x459A7B6E3D4Bab924108a012dCc1B4d87f98fDA5 
• Link: https://sepolia.scrollscan.com/address/0x459A7B6E3D4Bab924108a012dCc1B4d87f98fDA5#code 
• GitHub: https://github.com/fabriciojallaza/LinkPay 
• Slides (Presentation): https://gamma.app/docs/Copy-of-LinkPay-Secure-Payments-on-the-Blockchain-bps6l3xgoqlt8f8 
• Video: https://app.screencastify.com/watch/YqoeZRPvFS6VQMlqOSOB?checkOrg=bb074bbd-c455-4481-a9f7-7b654b09b383 

Description:

LinkPay is a decentralized, automated payroll platform that enables companies to pay employees in native USDC across multiple blockchain networks, using Wormhole CCTP for cross-chain transfers and Chainlink Automation for scheduled execution.

Traditional payroll systems are expensive, slow, and require manual intervention. LinkPay automates salary payments by combining Wormhole's burn-and-mint USDC transfers and Chainlink Automation to create a borderless, transparent, and self-operating payroll solution with no wrapped tokens.

How it works:

1. Company Registration:

   • A company registers on the platform (currently free for testing on testnet)
   • After registration, they can add employees with their salary amount and destination chain using Wormhole chain IDs

2. Automated Payroll Execution:

   • Chainlink Automation periodically calls the performUpkeep function every 5 minutes to execute payroll payments automatically
   • This eliminates manual intervention and ensures timely payments

3. Cross-Chain Native USDC Payments via Wormhole CCTP:

   • Same-chain payments (Base → Base): Direct USDC transfer with no additional fees
   • Cross-chain payments: Wormhole CCTP burns USDC on the source chain (Base Sepolia) and mints native USDC on the destination chain
   • No wrapped tokens – employees receive real, native USDC on their preferred blockchain
   • Automated relaying – no manual redemption required, fully automated delivery
   • Requires 0.01 ETH per cross-chain payment for Wormhole relayer fees

4. On-Chain State Updates:

   • Each transaction updates the state on-chain — transferring funds, updating employee payment schedules, and recording completed payments
   • Full transparency and traceability on blockchain explorers

Supported Networks (Wormhole Chain IDs):

Sponsors / Integrations:

SponsorProducts / Services UsedFilename and Line Reference

Challenges:

One of the main challenges was migrating from Chainlink CCIP to Wormhole CCTP to enable true native USDC payments across multiple blockchain networks (Base, Arbitrum, Avalanche, Optimism, and Ethereum).

Specifically, we had to:

• Integrate Wormhole's CircleIntegration interface with Circle's burn-and-mint mechanism
• Maintain Chainlink Automation compatibility while switching the cross-chain layer
• Handle chain ID mapping (transitioning from Chainlink's chain selectors to Wormhole's chain IDs)
• Ensure payments are executed reliably with proper error handling and gas estimation
• Test cross-chain transfers on multiple testnets and track them through WormholeScan

A significant part of the work involved testing and validating that payments were processed correctly, securely, and without errors across different chains. We also had to update the frontend to support Wormhole chain IDs while maintaining backward compatibility.

Finally, balancing security with ease of use for non-technical users was a constant design and development challenge.

What we learned:

Throughout the project, we learned:

Blockchain & Cross-Chain:

• How to integrate Wormhole CCTP for native USDC transfers using Circle's burn-and-mint mechanism
• Understanding the differences between wrapped tokens (Chainlink CCIP) vs native tokens (Wormhole CCTP)
• Working with Chainlink Automation to create truly automated, decentralized payment systems
• Managing blockchain transactions across multiple networks and monitoring their status in real-time
• Using Foundry (Forge, Cast, Anvil) for smart contract development, testing, and deployment

Frontend Development:

• Deepened knowledge of Next.js 16 with the App Router architecture
• Improved component structure, asynchronous data handling, and efficient state management
• Integrating ethers.js v5 for blockchain interactions
• Building responsive UI with Radix UI and Tailwind CSS 4

Smart Contract Development:

• Implementing complex multi-protocol integrations (Wormhole + Chainlink)
• Writing secure Solidity contracts with proper access control and error handling
• Optimizing gas costs for automated operations
• Contract verification on block explorers (BaseScan)

We gained valuable experience in deploying production-ready dApps that combine on-chain and off-chain logic, connecting user interfaces with blockchain data in a reliable and secure way.

Our goal is to make LinkPay the standard for decentralized, automated, cross-chain payroll that's ready for enterprise-level adoption while remaining accessible to small businesses and DAOs.

Technical Documentation:

For detailed technical information, see:

• Complete Integration Guide: WORMHOLE_INTEGRATION.md

Built with Wormhole CCTP 🪱 and Chainlink Automation ⚡