How to Build a Fast Web3 dApp with GetBlock’s Free RPC

Why Performance Matters in Web3 Why Performance Matters in Web3 In 2025, Web3 applications must compete with Web2's seamless experience. Slow transactions, laggy interfaces, and unreliable data plague many dApps, often owing to poorly optimized Remote Procedure Call (RPC) usage. Here, I tested GetBlock's free tier (5K daily requests, 5 RPS, and multi-chain support). Their paid plans have incredible features; however, for testing, the free tier still offers a decent opportunity to build production-ready dApps at zero cost—if you know how to optimize it. Here, I tested GetBlock's free tier production-ready dApps at zero cost I tested GetBlock’s incredible capabilities and attempted to organize the guide into easy-to-understand language. Essentially, this guide will walk you through building a cross-chain token bridge with real-time updates while maximizing GetBlock's free limits. cross-chain token bridge 📥 GetBlock RPC: Free Tier Capabilities & Strategic Advantages A. Free Plan Technical Specifications (2025 Update) A. Free Plan Technical Specifications (2025 Update) Throughput: 5 requests per second (RPS) Daily Limit: 5,000 requests Protocol Support: REST, JSON-RPC, WebSocket, gRPC, GraphQL Networks: 55+ blockchains (Ethereum, Solana, Polygon, BSC, etc.) Throughput: 5 requests per second (RPS) Throughput Daily Limit: 5,000 requests Daily Limit Protocol Support: REST, JSON-RPC, WebSocket, gRPC, GraphQL Protocol Support Networks: 55+ blockchains (Ethereum, Solana, Polygon, BSC, etc.) Networks This is a table with a more detailed description. Feature

Free Tier Limit

Ideal Use Case

Requests/Day

5,000

Prototypes, MVP dApps

Requests/Second

5 RPS

Wallet integrations

Chains Supported

55+ (EVM, Solana, etc.)

Cross-chain bridges

WebSocket Access

✅ Yes

Real-time event tracking Feature

Free Tier Limit

Ideal Use Case

Requests/Day

5,000

Prototypes, MVP dApps

Requests/Second

5 RPS

Wallet integrations

Chains Supported

55+ (EVM, Solana, etc.)

Cross-chain bridges

WebSocket Access

✅ Yes

Real-time event tracking Feature

Free Tier Limit

Ideal Use Case Feature Feature Feature Free Tier Limit Free Tier Limit Free Tier Limit Ideal Use Case Ideal Use Case Ideal Use Case Requests/Day

5,000

Prototypes, MVP dApps Requests/Day Requests/Day 5,000 5,000 Prototypes, MVP dApps Prototypes, MVP dApps Requests/Second

5 RPS

Wallet integrations Requests/Second Requests/Second 5 RPS 5 RPS Wallet integrations Wallet integrations Chains Supported

55+ (EVM, Solana, etc.)

Cross-chain bridges Chains Supported Chains Supported 55+ (EVM, Solana, etc.) 55+ (EVM, Solana, etc.) Cross-chain bridges Cross-chain bridges WebSocket Access

✅ Yes

Real-time event tracking WebSocket Access WebSocket Access ✅ Yes ✅ Yes Real-time event tracking Real-time event tracking 📥Hidden Advantages for Performance Optimization Multi-Chain Single API Key – Reduces complexity by managing Ethereum, Polygon, and Solana via one endpoint. Testnet Faucets – Free MATIC, ETH for rapid iteration. WebSocket for Real-Time Data: Avoid polling and saving requests. Multi-Chain Single API Key – Reduces complexity by managing Ethereum, Polygon, and Solana via one endpoint. Multi-Chain Single API Key Testnet Faucets – Free MATIC, ETH for rapid iteration. Testnet Faucets WebSocket for Real-Time Data: Avoid polling and saving requests. WebSocket for Real-Time Data What We're Building We are building a cross-chain token bridge that allows users to transfer tokens between Ethereum and Binance Smart Chain using a multichain wallet dashboard. The solution will include efficient RPC usage, real-time balance updates, and many more. It is gonna be interesting, stay tuned😊. Tech Stack Component

Technology

Purpose

Frontend

React + Vite

Fast UI rendering and state management

Blockchain

Ethers.js

RPC interactions, smart contract calls

Backend

Node.js (optional)

Caching and fallback layer for efficient use

RPC Provider

GetBlock Free Tier

BSC and ETH RPC data Component

Technology

Purpose

Frontend

React + Vite

Fast UI rendering and state management

Blockchain

Ethers.js

RPC interactions, smart contract calls

Backend

Node.js (optional)

Caching and fallback layer for efficient use

RPC Provider

GetBlock Free Tier

BSC and ETH RPC data Component

Technology

Purpose Component Component Component Technology Technology Technology Purpose Purpose Purpose Frontend

React + Vite

Fast UI rendering and state management Frontend Frontend React + Vite React + Vite Fast UI rendering and state management Fast UI rendering and state management Blockchain

Ethers.js

RPC interactions, smart contract calls Blockchain Blockchain Ethers.js Ethers.js RPC interactions, smart contract calls RPC interactions, smart contract calls Backend

Node.js (optional)

Caching and fallback layer for efficient use Backend Backend Node.js (optional) Node.js (optional) Caching and fallback layer for efficient use Caching and fallback layer for efficient use RPC Provider

GetBlock Free Tier

BSC and ETH RPC data RPC Provider RPC Provider GetBlock Free Tier GetBlock Free Tier BSC and ETH RPC data BSC and ETH RPC data Great — let us build the complete, in-depth Web3 dApp project using GetBlock’s free RPC tier in 2025. 📁 Final Project Directory 📁 Final Project Directory Make sure that your final project’s directory looks like this. You can update your directory according to the following diagram stepwise. 💻 Project Setup 💻 Project Setup 👉Initialize the Project 👉Initialize the Project mkdir ETH-bsc-bridge && cd ETH-bsc-bridge npm init -y npm install --save-dev hardhat npx hardhat mkdir ETH-bsc-bridge && cd ETH-bsc-bridge npm init -y npm install --save-dev hardhat npx hardhat Subsequently, the following dependencies should be installed: npm install dotenv ethers npm install --save-dev @nomicfoundation/hardhat-toolbox npm install dotenv ethers npm install --save-dev @nomicfoundation/hardhat-toolbox 👉Get Your GetBlock API Key 👉Get Your GetBlock API Key Sign up at GetBlock.io Grab your free API key from the dashboard Note your endpoints:

Sepolia RPC Testnet: https://go.getblock.io/YOUR_API_KEY (May not exhibit testnet balance in some cases if you are using Polygon Amoy ! ) Binance Smart Chain (BSC): https://go.getblock.io/YOUR_API_KEY Sign up at GetBlock.io GetBlock.io Grab your free API key from the dashboard Note your endpoints:

Sepolia RPC Testnet: https://go.getblock.io/YOUR_API_KEY (May not exhibit testnet balance in some cases if you are using Polygon Amoy ! ) Binance Smart Chain (BSC): https://go.getblock.io/YOUR_API_KEY Sepolia RPC Testnet: https://go.getblock.io/YOUR_API_KEY (May not exhibit testnet balance in some cases if you are using Polygon Amoy ! ) Binance Smart Chain (BSC): https://go.getblock.io/YOUR_API_KEY Sepolia RPC Testnet: https://go.getblock.io/YOUR_API_KEY (May not exhibit testnet balance in some cases if you are using Polygon Amoy ! ) https://go.getblock.io/YOUR_API_KEY Binance Smart Chain (BSC): https://go.getblock.io/YOUR_API_KEY https://go.getblock.io/YOUR_API_KEY ⚛️Configure .env File ⚛️Configure .env File Create .env in root: MNEMONIC="your_12 words mnemonic phrase" BSC_RPC_URL="https://bsc-testnet.getblock.io/YOUR_API_KEY/jsonrpc" SEPOLIA_RPC_URL="https://eth-testnet.getblock.io/YOUR_API_KEY/jsonrpc" MNEMONIC="your_12 words mnemonic phrase" BSC_RPC_URL="https://bsc-testnet.getblock.io/YOUR_API_KEY/jsonrpc" SEPOLIA_RPC_URL="https://eth-testnet.getblock.io/YOUR_API_KEY/jsonrpc" ⚠️ Always use TEST ACCOUNTS for development.⚠️ Keep mnemonic safe — don’t share it publicly. ⚠️ Always use TEST ACCOUNTS for development.⚠️ Keep mnemonic safe — don’t share it publicly. ⚡Update hardhat.config.js ⚡Update hardhat.config.js 👉Please update pre-created hardhat.config.js in the root directory. 👉 hardhat.config.js require("@nomicfoundation/hardhat-toolbox"); require("dotenv").config();

const { MNEMONIC, SEPOLIA_RPC_URL, BSC_RPC_URL } = process.env;

function getAccounts() { if (!MNEMONIC || MNEMONIC.split(" ").length !== 12) { console.warn("⚠️ Invalid MNEMONIC, no accounts loaded."); return []; } return { mnemonic: MNEMONIC }; }

module.exports = { solidity: "0.8.20", defaultNetwork: "sepolia", networks: { sepolia: { url: SEPOLIA_RPC_URL, accounts: getAccounts(), gasPrice: 25_000_000_000, timeout: 60_000, }, bscTestnet: { url: BSC_RPC_URL, accounts: getAccounts(), gasPrice: 25_000_000_000, }, }, }; require("@nomicfoundation/hardhat-toolbox"); require("dotenv").config();

const { MNEMONIC, SEPOLIA_RPC_URL, BSC_RPC_URL } = process.env;

function getAccounts() { if (!MNEMONIC || MNEMONIC.split(" ").length !== 12) { console.warn("⚠️ Invalid MNEMONIC, no accounts loaded."); return []; } return { mnemonic: MNEMONIC }; }

module.exports = { solidity: "0.8.20", defaultNetwork: "sepolia", networks: { sepolia: { url: SEPOLIA_RPC_URL, accounts: getAccounts(), gasPrice: 25_000_000_000, timeout: 60_000, }, bscTestnet: { url: BSC_RPC_URL, accounts: getAccounts(), gasPrice: 25_000_000_000, }, }, }; 💡Smart Contracts – Lock & Mint 💡Smart Contracts – Lock & Mint We'll create three essential contracts here: ✅ Token.sol — ERC20 token deployed on both BSC & ETH ✅ BSCBridge.sol — Lock tokens & emit event on BSC ✅ ETHBridge.sol — Mint tokens on Ethereum (only by admin/relayer) ✅ Token.sol — ERC20 token deployed on both BSC & ETH Token.sol ✅ BSCBridge.sol — Lock tokens & emit event on BSC BSCBridge.sol ✅ ETHBridge.sol — Mint tokens on Ethereum (only by admin/relayer) ETHBridge.sol 📁 Location 📁 Location All smart contracts go into:/contracts/ /contracts/ Please re-check the directory structure in the Figure 1. 1️⃣ Token.sol – Shared Token Contract 1️⃣ Token.sol – Shared Token Contract Basic ERC20 token. 📄 contracts/Token.sol contracts/Token.sol // SPDX-License-Identifier: MIT pragma solidity ^0.8.20;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol"; import "@openzeppelin/contracts/access/Ownable.sol";

contract BridgeToken is ERC20, Ownable { constructor(address initialOwner) ERC20("BridgeToken", "BRG") { _mint(initialOwner, 1_000_000 * 10 ** decimals()); transferOwnership(initialOwner); // This sets the initial owner (e.g., bridge contract later) }

function mint(address to, uint256 amount) external onlyOwner { _mint(to, amount); } } // SPDX-License-Identifier: MIT pragma solidity ^0.8.20;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol"; import "@openzeppelin/contracts/access/Ownable.sol";

contract BridgeToken is ERC20, Ownable { constructor(address initialOwner) ERC20("BridgeToken", "BRG") { _mint(initialOwner, 1_000_000 * 10 ** decimals()); transferOwnership(initialOwner); // This sets the initial owner (e.g., bridge contract later) }

function mint(address to, uint256 amount) external onlyOwner { _mint(to, amount); } } 2️⃣ BSCBridge.sol – Lock Contract on BSC 2️⃣ BSCBridge.sol – Lock Contract on BSC This locks tokens and emits TokenLocked event. 📄 contracts/BSCBridge.sol contracts/BSCBridge.sol // SPDX-License-Identifier: MIT pragma solidity ^0.8.20;

import "./BridgeToken.sol";

contract BSCBridge { BridgeToken public token; address public admin;

event TokenMinted(address indexed user, uint256 amount);

constructor(address tokenAddress) { token = BridgeToken(tokenAddress); admin = msg.sender; }

function mintTokens(address to, uint256 amount) external { require(msg.sender == admin, "Only admin can mint"); token.mint(to, amount); emit TokenMinted(to, amount); } } // SPDX-License-Identifier: MIT pragma solidity ^0.8.20;

import "./BridgeToken.sol";

contract BSCBridge { BridgeToken public token; address public admin;

event TokenMinted(address indexed user, uint256 amount);

constructor(address tokenAddress) { token = BridgeToken(tokenAddress); admin = msg.sender; }

function mintTokens(address to, uint256 amount) external { require(msg.sender == admin, "Only admin can mint"); token.mint(to, amount); emit TokenMinted(to, amount); } } 🧠 How it works:

Users approve and call lockTokens Contract emits TokenLocked Backend listens and triggers mint on BSC 🧠 How it works: How it works: Users approve and call lockTokens Contract emits TokenLocked Backend listens and triggers mint on BSC Users approve and call lockTokens lockTokens Contract emits TokenLocked TokenLocked Backend listens and triggers mint on BSC 3️⃣ ETHBridge.sol – Mint Contract on Ethereum 3️⃣ ETHBridge.sol – Mint Contract on Ethereum Only a trusted relayer (admin) can mint tokens. 📄 contracts/ETHBridge.sol contracts/ETHBridge.sol // SPDX-License-Identifier: MIT pragma solidity ^0.8.20;

import "./BridgeToken.sol";

contract ETHBridge { BridgeToken public token; address public admin;

event TokenLocked(address indexed user, uint256 amount, address targetAddress);

constructor(address tokenAddress) { token = BridgeToken(tokenAddress); admin = msg.sender; }

function lockTokens(uint256 amount, address targetAddress) external { require(amount > 0, "Amount must be greater than 0"); token.transferFrom(msg.sender, address(this), amount); emit TokenLocked(msg.sender, amount, targetAddress); }

function withdraw(address to, uint256 amount) external { require(msg.sender == admin, "Only admin"); token.transfer(to, amount); } } // SPDX-License-Identifier: MIT pragma solidity ^0.8.20;

import "./BridgeToken.sol";

contract ETHBridge { BridgeToken public token; address public admin;

event TokenLocked(address indexed user, uint256 amount, address targetAddress);

constructor(address tokenAddress) { token = BridgeToken(tokenAddress); admin = msg.sender; }

function lockTokens(uint256 amount, address targetAddress) external { require(amount > 0, "Amount must be greater than 0"); token.transferFrom(msg.sender, address(this), amount); emit TokenLocked(msg.sender, amount, targetAddress); }

function withdraw(address to, uint256 amount) external { require(msg.sender == admin, "Only admin"); token.transfer(to, amount); } } 🧠 How it works:

Backend (trusted relayer) listens to BSC events Calls mintTokens on Ethereum Sepolia via private key Tokens minted for user 🧠 How it works: How it works: Backend (trusted relayer) listens to BSC events Calls mintTokens on Ethereum Sepolia via private key Tokens minted for user Backend (trusted relayer) listens to BSC events Calls mintTokens on Ethereum Sepolia via private key mintTokens Tokens minted for user 4️⃣ Deploy Scripts 4️⃣ Deploy Scripts Wait, don’t forget to install dependency for Contracts: npm install @openzeppelin/contracts npm install @openzeppelin/contracts 👉Create scripts/deployBSC.js: scripts/deployBSC.js const hre = require("hardhat");

async function main() { const [deployer] = await hre.ethers.getSigners(); console.log("Deploying to BSC Testnet from:", deployer.address);

// Deploy BridgeToken (owned by deployer for now) const BridgeToken = await hre.ethers.getContractFactory("BridgeToken"); const token = await BridgeToken.deploy(deployer.address); await token.waitForDeployment(); const tokenAddress = await token.getAddress(); console.log("✅ BridgeToken (BSC) deployed at:", tokenAddress);

// Deploy BSCBridge const BSCBridge = await hre.ethers.getContractFactory("BSCBridge"); const bridge = await BSCBridge.deploy(tokenAddress); await bridge.waitForDeployment(); const bridgeAddress = await bridge.getAddress(); console.log("✅ BSCBridge deployed at:", bridgeAddress);

// Transfer token ownership to BSCBridge so it can mint const tx = await token.transferOwnership(bridgeAddress); await tx.wait(); console.log("🔑 Token ownership transferred to BSCBridge."); }

main().catch((error) => { console.error("🚨 Deployment failed:", error); process.exitCode = 1; }); const hre = require("hardhat");

async function main() { const [deployer] = await hre.ethers.getSigners(); console.log("Deploying to BSC Testnet from:", deployer.address);

// Deploy BridgeToken (owned by deployer for now) const BridgeToken = await hre.ethers.getContractFactory("BridgeToken"); const token = await BridgeToken.deploy(deployer.address); await token.waitForDeployment(); const tokenAddress = await token.getAddress(); console.log("✅ BridgeToken (BSC) deployed at:", tokenAddress);

// Deploy BSCBridge const BSCBridge = await hre.ethers.getContractFactory("BSCBridge"); const bridge = await BSCBridge.deploy(tokenAddress); await bridge.waitForDeployment(); const bridgeAddress = await bridge.getAddress(); console.log("✅ BSCBridge deployed at:", bridgeAddress);

// Transfer token ownership to BSCBridge so it can mint const tx = await token.transferOwnership(bridgeAddress); await tx.wait(); console.log("🔑 Token ownership transferred to BSCBridge."); }

main().catch((error) => { console.error("🚨 Deployment failed:", error); process.exitCode = 1; }); 👉Create scripts/deployETH.js: scripts/deployETH.js const hre = require("hardhat");

async function main() { const [deployer] = await hre.ethers.getSigners(); console.log("Deploying to Sepolia from:", deployer.address);

// Deploy BridgeToken const BridgeToken = await hre.ethers.getContractFactory("BridgeToken"); const token = await BridgeToken.deploy(deployer.address); await token.waitForDeployment(); const tokenAddress = await token.getAddress(); console.log("✅ BridgeToken (Sepolia) deployed at:", tokenAddress);

// Deploy ETHBridge const ETHBridge = await hre.ethers.getContractFactory("ETHBridge"); const bridge = await ETHBridge.deploy(tokenAddress); await bridge.waitForDeployment(); const bridgeAddress = await bridge.getAddress(); console.log("✅ ETHBridge deployed at:", bridgeAddress); }

main().catch((error) => { console.error("🚨 Deployment failed:", error); process.exitCode = 1; }); const hre = require("hardhat");

async function main() { const [deployer] = await hre.ethers.getSigners(); console.log("Deploying to Sepolia from:", deployer.address);

// Deploy BridgeToken const BridgeToken = await hre.ethers.getContractFactory("BridgeToken"); const token = await BridgeToken.deploy(deployer.address); await token.waitForDeployment(); const tokenAddress = await token.getAddress(); console.log("✅ BridgeToken (Sepolia) deployed at:", tokenAddress);

// Deploy ETHBridge const ETHBridge = await hre.ethers.getContractFactory("ETHBridge"); const bridge = await ETHBridge.deploy(tokenAddress); await bridge.waitForDeployment(); const bridgeAddress = await bridge.getAddress(); console.log("✅ ETHBridge deployed at:", bridgeAddress); }

main().catch((error) => { console.error("🚨 Deployment failed:", error); process.exitCode = 1; }); 5️⃣ Deploy the Contracts 5️⃣ Deploy the Contracts This time, we deploy our contracts to the blockchain. Before this, make sure to have testnet tokens for the BSC and Ethereum testnets in your MetaMask wallet. They can be obtained from free faucet sites such as the GetBlock, and BNB faucet. GetBlock BNB faucet First, let us try to deploy a contract to the BSC test; the run command npx hardhat compiles to compile, and then run the following command at the terminal: npx hardhat compiles npx hardhat run scripts/deployBSC.js --network bscTestnet npx hardhat run scripts/deployBSC.js --network bscTestnet Once you deploy the contract to the testnet, you will see the following output in the terminal: Second, the contract was deployed to the Ethereum Sepolia testnet. Run the following command at the terminal: npx hardhat run scripts/deployEth.js --network sepolia npx hardhat run scripts/deployEth.js --network sepolia The output of the terminal should be similar if everything is correct. Note: Please keep both the contract addresses from the BSC and Ethereum deployment to update.env files for the next step. The tokens deployed here are BRG and they can be tracked on BSC testnet and Ethereum Sepolia testnet explorers. Note: Please keep both the contract addresses from the BSC and Ethereum deployment to update.env files for the next step. The tokens deployed here are BRG and they can be tracked on BSC testnet and Ethereum Sepolia testnet explorers. .env ⚙️Backend Listener — Token Bridge Relayer ⚙️Backend Listener — Token Bridge Relayer The relayer service listens to events from the BSC Bridge and calls the mintTokens() function of the Ethereum Bridge. relayer service BSC Bridge Ethereum Bridge 📁 Directory Structure Update 📁 Directory Structure Update Create the backend/ directory in your root folder: backend/ mkdir backend && cd backend npm init -y npm install ethers dotenv mkdir backend && cd backend npm init -y npm install ethers dotenv 🔐 .env (Root-level) 🔐 .env (Root-level) Now, we update with the following details .env file. .env BSC_BRIDGE="0x...your deployed BSCBridge address" SEPOLIA_RPC_URL="0x...your deployed EthereumBridge address" SEPOLIA_TOKEN="0x...your ETH token address" BSC_BRIDGE="0x...your deployed BSCBridge address" SEPOLIA_RPC_URL="0x...your deployed EthereumBridge address" SEPOLIA_TOKEN="0x...your ETH token address" 🧠 You must replace the above values with real deployed addresses. 🧠 You must replace the above values with real deployed addresses. real deployed addresses 📄 backend/index.js — Main Relayer Logic 📄 backend/index.js — Main Relayer Logic require("dotenv").config({ path: __dirname + "/../.env" });

const { ethers } = require("ethers");

// Load environment variables const { MNEMONIC, SEPOLIA_WS_URL, SEPOLIA_BRIDGE, BSC_RPC_URL, BSC_BRIDGE } = process.env;

// Validate env variables if (!MNEMONIC || !SEPOLIA_WS_URL || !SEPOLIA_BRIDGE || !BSC_RPC_URL || !BSC_BRIDGE) { console.error("❌ Missing environment variables. Check .env file."); process.exit(1); }

// Create wallet from mnemonic let wallet; try { wallet = ethers.Wallet.fromPhrase(MNEMONIC); } catch (err) { console.error("❌ Invalid MNEMONIC:", err.message); process.exit(1); }

// Providers const sepoliaProvider = new ethers.WebSocketProvider(SEPOLIA_WS_URL); const bscProvider = new ethers.JsonRpcProvider(BSC_RPC_URL); const bscSigner = wallet.connect(bscProvider);

// Contract ABIs const ETH_BRIDGE_ABI = [ "event TokenLocked(address indexed user, uint256 amount, address targetAddress)" ]; const BSC_BRIDGE_ABI = [ "function mintTokens(address to, uint256 amount) external" ];

// Contract instances const ethBridge = new ethers.Contract(SEPOLIA_BRIDGE, ETH_BRIDGE_ABI, sepoliaProvider); const bscBridge = new ethers.Contract(BSC_BRIDGE, BSC_BRIDGE_ABI, bscSigner);

// In-memory cache to avoid duplicate processing const processedTxs = new Set();

async function replayPastEvents(fromBlock = null, toBlock = "latest") { console.log("🔁 Scanning past events...");

if (!fromBlock) { const currentBlock = await sepoliaProvider.getBlockNumber(); fromBlock = currentBlock - 10000; // Lookback 10K blocks if (fromBlock < 0) fromBlock = 0; }

if (toBlock === "latest") { toBlock = await sepoliaProvider.getBlockNumber(); }

const step = 2000; for (let start = fromBlock; start toBlock) end = toBlock;

console.log(`📦 Querying blocks: ${start} → ${end}`);

try { const logs = await ethBridge.queryFilter("TokenLocked", start, end);

for (const event of logs) { const { user, amount, targetAddress } = event.args; const txHash = event.transactionHash;

if (processedTxs.has(txHash)) { console.log("⚠️ Already processed:", txHash); continue; }

processedTxs.add(txHash); console.log(`🔒 Replaying: ${user} locked ${ethers.formatEther(amount)} BRG → ${targetAddress}`);

try { const tx = await bscBridge.mintTokens(targetAddress, amount); await tx.wait(); console.log(`✅ Minted ${ethers.formatEther(amount)} BRG on BSC for ${targetAddress}`); } catch (err) { console.error("❌ Minting failed:", err.message); } } } catch (err) { console.error(`❌ Error querying blocks ${start} → ${end}:`, err.message); } } }

async function startRelayer() { console.log("🚀 Relayer started. Listening for real-time TokenLocked events...");

ethBridge.on("TokenLocked", async (user, amount, targetAddress, event) => { const txHash = event.transactionHash;

if (processedTxs.has(txHash)) { console.log("⚠️ Duplicate real-time event skipped:", txHash); return; }

processedTxs.add(txHash); console.log(`🔒 Detected real-time lock: ${user} locked ${ethers.formatEther(amount)} BRG → ${targetAddress}`);

try { const tx = await bscBridge.mintTokens(targetAddress, amount); await tx.wait(); console.log(`✅ Minted ${ethers.formatEther(amount)} BRG on BSC for ${targetAddress}`); } catch (err) { console.error("❌ Real-time minting failed:", err.message); } }); }

// Start everything (async () => { await replayPastEvents(); await startRelayer(); })(); require("dotenv").config({ path: __dirname + "/../.env" });