BridgePay

The Problem
1.7 billion people — roughly half the world's adult population — have no access to a bank account. Yet many are migrant workers sending money home to families in Africa, Asia, and Latin America. They rely on predatory services like Western Union and MoneyGram that charge 7–15% per transfer, take 3–5 business days, require government-issued ID, and are inaccessible without a smartphone or physical branch. For a worker sending $200 home, that's up to $30 lost in fees every single time. Over a year, that's hundreds of dollars stolen from the world's most vulnerable people.
What BridgePay Is
BridgePay is a decentralized cross-border remittance and micro-savings platform built on Chainlink's infrastructure. It lets anyone — even without a bank account or government ID — send money across borders in minutes at under 0.3% fee, and automatically grow a portion of every transfer into savings toward a personal financial goal.
How It Works
The system has three layers working together:

1. Identity Without Documents (Worldcoin World ID) The biggest barrier for the unbanked is KYC — they have no passport, no driver's license, no utility bill. BridgePay replaces document-based identity with Worldcoin's World ID: a zero-knowledge proof generated from an iris scan that proves a person is a unique human being without revealing who they are. Once verified, the proof is recorded on-chain and gates all transfers. No documents. No bank. No bureaucracy — just proof you're human.
2. Cross-Chain Remittance (Chainlink CCIP + CRE) When a sender initiates a transfer on Ethereum Sepolia, a Chainlink CRE (Chainlink Runtime Environment) workflow triggers automatically. The workflow reads live USDC/USD exchange rates from Chainlink Data Feeds to calculate a transparent, manipulation-proof FX rate, runs a two-layer compliance check (World ID humanity verification + AML pattern detection), and upon approval executes an atomic cross-chain transfer via Chainlink CCIP from the sender's chain (Ethereum) to the recipient's chain (Base). The recipient receives funds directly to their wallet — no intermediary holds the money at any point.
3. Automatic Micro-Savings (BridgePayVault) Every transfer automatically splits a configurable percentage (default 10%) into a non-custodial savings vault on Base. Recipients can create named savings goals — school fees, medical emergencies, small business capital — and watch their balance grow with every remittance received. They can withdraw any time, with no lockup. For families who have never had a savings account, this is a first step into formal financial participation.
   Technical Architecture

• BridgePayWorldID — Solidity contract wrapping Worldcoin's IWorldID.verifyProof() with nullifier-hash sybil resistance, binding each proof to a single wallet address
• BridgePayRemittance — CCIP-enabled sender contract on Ethereum Sepolia with World ID gate, Chainlink Data Feed FX pricing, daily limits, and CRE workflow integration
• BridgePayReceiver — CCIP receiver on Base Sepolia that splits incoming funds between direct payout and the savings vault
• BridgePayVault — Non-custodial micro-savings vault with per-user goal tracking
• Chainlink CRE Workflow — TypeScript offchain workflow running on a DON that orchestrates compliance, pricing, and execution with cryptographic reporting back on-chain
• Compliance API — Lightweight AML layer that adjusts risk scoring based on World ID verification status, transfer patterns, and volume thresholds
• Mobile-first Frontend — Progressive web app with MetaMask/WalletConnect integration and embedded IDKit for World ID verification in-browser
  What Makes It Different
  Most DeFi remittance solutions still require a crypto-native user with a funded wallet and a government ID for KYC. BridgePay is designed from the ground up for people who have neither. World ID provides identity via biometrics. Chainlink CCIP provides settlement without a bank. The savings vault provides financial growth without a savings account. Together, they form a complete financial entry point for the 1.7 billion people the current system has written off.

BridgePay is built on four Chainlink services working in concert, with smart contracts on two chains and an offchain automation layer connecting them.
Chainlink CRE (Core) The heart of the system is a TypeScript workflow running on Chainlink's Runtime Environment — a decentralized offchain compute layer. A CronTrigger polls the remittance contract every 5 minutes. When a pending transfer is detected, the workflow uses EVMClient to read live USDC/USD prices from Chainlink Data Feeds, applies staleness checks and sanity bounds, then calls a compliance API for AML screening. On approval, it calls EVMClient.writeReport() to cryptographically submit the execution result back on-chain, triggering the actual CCIP transfer. No centralized backend controls the flow — the DON does.
Chainlink CCIP (Cross-Chain Transfer) BridgePayRemittance on Ethereum Sepolia constructs a CCIP message containing the token amount, recipient address, and savings split percentage, then sends it via the CCIP Router. BridgePayReceiver on Base Sepolia receives the message atomically, splits funds between the recipient wallet and the savings vault, and handles any failed messages with a retry mechanism.
Chainlink Data Feeds (FX Pricing) The workflow reads the USDC/USD price feed on-chain before every transfer. The exchange rate is transparently derived from this feed — users always see exactly where the rate comes from, with no hidden spread.
Worldcoin World ID (Identity) BridgePayWorldID wraps Worldcoin's IWorldID interface. Users verify their humanity via an iris scan using the IDKit widget in the frontend, which generates a ZK proof. The proof is verified on-chain via verifyProof(), and the sender's nullifierHash is recorded to prevent any one person from verifying more than once (sybil resistance). The BridgePayRemittance contract checks isVerified(msg.sender) as the first gate on every transfer — no World ID, no transfer.
Smart Contracts (Solidity 0.8.24) Four contracts form the on-chain layer: BridgePayWorldID (identity verifier), BridgePayRemittance (CCIP sender with daily limits, fee logic, and CRE integration), BridgePayReceiver (CCIP receiver with defensive try/catch and stuck-fund recovery), and BridgePayVault (non-custodial micro-savings with per-user goal tracking). All use OpenZeppelin's ReentrancyGuard, Ownable, and SafeERC20.
Infrastructure Contracts are deployed and verified on Tenderly Virtual TestNets (forks of Ethereum Sepolia and Base Sepolia), enabling gas-free testing with unlimited faucet funds and full transaction traceability on Tenderly Explorer. Hardhat with @tenderly/hardhat-tenderly handles deployment with automaticVerifications: true. A lightweight Node.js compliance API handles AML pattern detection and Worldcoin cloud verification as a second layer of security.
Frontend A mobile-first progressive web app (single HTML file, no framework dependencies) connects via MetaMask/WalletConnect, embeds the Worldcoin IDKit widget for in-browser World ID verification, and communicates directly with the smart contracts via ethers.js. Designed to work on low-end Android devices with slow internet — the primary device type of the target users.