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:

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