Send a gasless transaction

This tutorial guides you through the process of creating a user operation, obtaining sponsorship from FuseBox’s verifying paymaster, and submitting this sponsored user operation on-chain using the bundler. By leveraging FuseBox’s capabilities, you can execute on-chain transactions efficiently and without the need for gas.

Obtain an API Key

Start by visiting our Operator Dashboard to generate an API key, a crucial step for accessing our services.

Clone the FuseBox Tutorial Template Repository

We’ve prepared a FuseBox tutorial template repository with Typescript, viem, and @fuseio/fusebox-web-sdk to help you get started. Clone the repository and prepare your development environment by executing the following commands:

git clone https://github.com/fuseio/tutorial-template.git fusebox-tutorial
cd fusebox-tutorial
npm install

The primary file you’ll be working with is index.ts. Verify your setup by running npm start; you should see Hello world! in the console.

Generate a Private Key

Securely generate and store a private key using the code snippet below in index.ts:

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

Initialize the SDK

With FuseSDK, you can create User Operations for ERC-4337 Etherspot Smart Accounts, Bundler services, or Paymasters. It is open source and MIT licensed for maximum flexibility. Ensure you 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, {
  withPaymaster: true,
});

Create a Smart Contract Wallet

Use the SDK and your private key to initialize the Etherspot Smart Account. Display the smart account address by running:

console.log(
  `Smart account address: https://explorer.fuse.io/address/${fuseSDK.wallet.getSender()}`
);

This smart account is counterfactual, meaning it will be deployed on-chain with your first transaction.

Submit a Transaction

Submit a transaction from the smart account to 0xd8da6bf26964af9d7eed9e03e53415d37aa96045 (vitalik.eth) using 0x1234 as the call data. The FuseSDK will facilitate this operation, including obtaining sponsorship and submission:

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();

console.log(
  `User operation included: https://explorer.fuse.io/tx/${receipt?.transactionHash}`
);

Running this will display the transaction hash and confirm your operation is on-chain. Congratulations! You’ve executed a gasless transaction, deployed a smart account, verified its signature, had the operation sponsored, and performed a transaction to vitalik.eth - all seamlessly with a few lines of code. Should you have any questions or wish to share your project, please reach out to us.

Building on Fuse

FuseBox

Web3 Tools

Charge

Subgraphs

Tutorials

Obtain an API Key

Clone the FuseBox Tutorial Template Repository

Generate a Private Key

Initialize the SDK

Create a Smart Contract Wallet

Submit a Transaction

​Obtain an API Key

​Clone the FuseBox Tutorial Template Repository

​Generate a Private Key

​Initialize the SDK

​Create a Smart Contract Wallet

​Submit a Transaction

Obtain an API Key

Clone the FuseBox Tutorial Template Repository

Generate a Private Key

Initialize the SDK

Create a Smart Contract Wallet

Submit a Transaction