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Send your first transaction


In this tutorial, you will learn how to submit your first transaction using a smart contract wallet. You'll be guided through setting up the necessary client with @fuseio/fusebox-web-sdk, creating a user operation, obtaining sponsorship from FuseBox's verifying paymaster, and finally submitting it on-chain using FuseBox's bundler.

Obtain an API Key

To begin, navigate to our Operator Dashboard and generate an API key. This key is essential for accessing our services.

Clone the FuseBox Tutorial Template Repository

To facilitate your start, we've prepared a FuseBox tutorial template repository equipped with Typescript, viem, and @fuseio/fusebox-web-sdk. Follow these steps to clone the repository and set up your environment:

git clone fusebox-tutorial
cd fusebox-tutorial

Proceed by installing the dependencies:

npm install

We'll mainly work with the index.ts file. Test your setup by running:

npm start

If set up correctly, you should see Hello world! printed in the console.

Generate a Private Key

Generate a private key and store it securely. Use the following code snippet in index.ts:

const privateKey =
process.env.PRIVATE_KEY ??
(() => {
const pk = generatePrivateKey();
writeFileSync(".env", `PRIVATE_KEY=${pk}`);
return pk;

Initialize the SDK

FuseSDK enables the creation of User Operations for ERC-4337 Etherspot Smart Account, Bundler service, or Paymaster. It's open source and MIT licensed, offering flexibility and no lock-in. Replace YOUR_FUSEBOX_API_KEY with your actual API key:

const apiKey = "YOUR_FUSEBOX_API_KEY";
const credentials = new ethers.Wallet(privateKey);
const fuseSDK = await FuseSDK.init(apiKey, credentials);

Create a smart contract wallet

Initialize the SDK with the previously generated private key to create the Etherspot Smart Account:

`Smart account address:${fuseSDK.wallet.getSender()}`

Running this code will display the smart account address in the console. Note that the smart account is counterfactual and will be deployed on-chain when you send a transaction.

Submit a Transaction

Now, let's submit a transaction from the smart account. We'll send a transaction to 0xd8da6bf26964af9d7eed9e03e53415d37aa96045 (vitalik.eth) with 0x1234 as example call data. FuseSDK will handle the operations (but you need to fund the account with some FUSE yourself first):

const to = "0xd8da6bf26964af9d7eed9e03e53415d37aa96045"; // for vitalik.eth
const value = ethers.utils.parseEther("0");
const data = new TextEncoder().encode("0x1234");
const res = await fuseSDK.callContract(to, value, data);

console.log(`UserOpHash: ${res?.userOpHash}`);
console.log("Waiting for transaction...");

const receipt = await res?.wait();

`User operation included:${receipt?.transactionHash}`

Upon running, you'll see the transaction hash and confirmation that your operation is on-chain.

Congratulations! You've successfully sent a transaction, deploying a smart account, verifying its signature, having the operation sponsored, and executing a transaction—all with just a few lines of code.

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