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

Next Steps

Build transaction workflows: quicknode-core-workflow-a