quicknode-hello-world

QuickNode Hello World

Overview

Make your first blockchain queries: get block number, check ETH balance, read a smart contract.

Prerequisites

• Completed quicknode-install-auth with endpoint URL

Instructions

Step 1: Get Block Number

import { ethers } from 'ethers';
const provider = new ethers.JsonRpcProvider(process.env.QUICKNODE_ENDPOINT);

const blockNumber = await provider.getBlockNumber();
console.log(`Current block: ${blockNumber}`);

Step 2: Check ETH Balance

const address = '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045'; // vitalik.eth
const balance = await provider.getBalance(address);
console.log(`Balance: ${ethers.formatEther(balance)} ETH`);

Step 3: Read Smart Contract (ERC-20 Token)

const usdcAddress = '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48';
const abi = ['function balanceOf(address) view returns (uint256)', 'function decimals() view returns (uint8)'];
const usdc = new ethers.Contract(usdcAddress, abi, provider);

const decimals = await usdc.decimals();
const balance = await usdc.balanceOf(address);
console.log(`USDC balance: ${ethers.formatUnits(balance, decimals)}`);

Step 4: Get Transaction Receipt

const txHash = '0xabc...'; // Any transaction hash
const receipt = await provider.getTransactionReceipt(txHash);
console.log(`Status: ${receipt?.status === 1 ? 'Success' : 'Failed'}`);
console.log(`Gas used: ${receipt?.gasUsed.toString()}`);

Output

• Block number retrieved
• ETH balance checked
• ERC-20 contract read
• Transaction receipt fetched

Error Handling

Error	Cause	Solution
null receipt	TX pending or invalid hash	Wait for confirmation or verify hash
call revert exception	Wrong ABI or address	Verify contract address and ABI
Balance is 0n	Address has no ETH	Try a known address like vitalik.eth

Resources

• QuickNode Ethereum API
• ethers.js Documentation

Next Steps

Build transaction workflows: quicknode-core-workflow-a