How to Get the Latest Block on Ethereum

This guide assumes you've gone through the getting started steps and have an Alchemy account!

1. From your command line, create a new project directory and cd into it:

mkdir web3-example
cd web3-example

2. Install a web3 library

You can use any web3 library of your choosing. We recommend Viem for new projects, or Ethers.js if you're already familiar with it.

npm install viem

3. Create a file named index.js and add the following contents:

import { createPublicClient, http } from 'viem'
import { mainnet } from 'viem/chains'
 
// Replace with your Alchemy API Key
const apiKey = "demo"; // Replace with your Alchemy API Key.
 
const publicClient = createPublicClient({
  chain: mainnet,
  transport: http(`https://eth-mainnet.g.alchemy.com/v2/${apiKey}`)
})
 
async function main() {
  try {
    const latestBlock = await publicClient.getBlockNumber();
    console.log("The latest block number is", latestBlock);
  } catch (error) {
    console.error('Request failed:', error.message);
  }
}
 
main();

Unfamiliar with the async stuff? Check out this Medium post.

4. Run it using node

node index.js

5. You should now see the latest block number output in your console!

The latest block number is 11043912

Woo! Congrats! You just wrote your first web3 script using Alchemy 🎉

Once you complete this tutorial, let us know how your experience was or if you have any feedback by tagging us on Twitter @Alchemy!

Not sure what to do next? Build upon your skills learned in this tutorial by checking out our beginner's tutorial for sending Ethereum transactions using Web3 and Alchemy.