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Tutorial 1 — Send your first gasless transaction

In this tutorial, you will submit your first fully-gasless transaction from a smart account.

You will set up the necessary permissionless.js clients, create a user operation, ask Pimlico's verifying paymaster to sponsor it, and then submit it on-chain with Pimlico's bundler.

Steps

Get a Pimlico API key

To get started, please go to our dashboard and generate a Pimlico API key.

Clone the Pimlico tutorial template repository

We have created a Pimlico tutorial template repository that you can use to get started. It comes set up with Typescript, viem, and permissionless.js.

git clone https://github.com/pimlicolabs/tutorial-template.git pimlico-tutorial-1
cd pimlico-tutorial-1

Now, let's install the dependencies:

npm install

The main file we will be working with is index.ts. Let's run it to make sure everything is working:

npm start

If everything has been set up correctly, you should see Hello world! printed to the console.

Create the public and paymaster clients, and generate a private key

The public client will be responsible for querying the blockchain, while the paymaster client will be responsible for interacting with Pimlico's verifying paymaster endpoint and requesting sponsorship.

Make sure to replace YOUR_PIMLICO_API_KEY in the code below with your actual Pimlico API key.

Let's open up index.ts, and add the following to the bottom:

const apiKey = "YOUR_PIMLICO_API_KEY"
const paymasterUrl = `https://api.pimlico.io/v2/sepolia/rpc?apikey=${apiKey}`
 
const privateKey =
	(process.env.PRIVATE_KEY as Hex) ??
	(() => {
		const pk = generatePrivateKey()
		writeFileSync(".env", `PRIVATE_KEY=${pk}`)
		return pk
	})()
 
export const publicClient = createPublicClient({
	transport: http("https://rpc.ankr.com/eth_sepolia"),
})
 
export const paymasterClient = createPimlicoPaymasterClient({
	transport: http(paymasterUrl),
})

Create the SmartAccount instance

For the purposes of this guide, we will be using Safe accounts. This account is an ERC-4337 wallet controlled by a single EOA signer.

To create the Safe account, we will use the privateKeyToSafeSmartAccount utility function from permissionless.js. We need to specify the Safe version we are using as well as the global ERC-4337 EntryPoint address. For the signer, we will be using the previously generated private key.

Add the following to the bottom of index.ts:

const account = await privateKeyToSafeSmartAccount(publicClient, {
	privateKey,
	safeVersion: "1.4.1", // simple version
	entryPoint: "0x5FF137D4b0FDCD49DcA30c7CF57E578a026d2789", // global entrypoint
})
 
console.log(`Smart account address: https://sepolia.etherscan.io/address/${account.address}`)

Let's run this code with npm start. You should see the smart account address printed to the console.

Smart account address: https://sepolia.etherscan.io/address/0x374b42bCFAcf85FDCaAB84774EA15ff36D42cdA7

Create the bundler and smart account clients and fetch the gas price

Now that we have a SmartAccount instance, we need to create a SmartAccountClient instance to make transact from it. SmartAccountClient is an almost drop-in replacement for a viem WalletClient, but it also includes some additional functionality for interacting with smart accounts.

We also extend the SmartAccountClient with bundler actions and Pimlico-specific bundler actions so we can fetch the appropriate gas price.

We also specify the optional sponsorUserOperation middleware function, calling the sponsorUserOperation function from the paymaster client. This will make sure that the user operation is sponsored by Pimlico's verifying paymaster.

Finally, we will fetch the gas price from the bundler that we will use to submit the user operation in the next step.

Add the following to the bottom of index.ts:

const bundlerUrl = `https://api.pimlico.io/v1/sepolia/rpc?apikey=${apiKey}`
 
const smartAccountClient = createSmartAccountClient({
	account,
	chain: sepolia,
	transport: http(bundlerUrl),
	sponsorUserOperation: paymasterClient.sponsorUserOperation,
})
	.extend(bundlerActions)
	.extend(pimlicoBundlerActions)
 
const gasPrices = await smartAccountClient.getUserOperationGasPrice()
 
console.log("Received gas prices:", gasPrices)

Let's run this code with npm start. You should see the gas prices printed to the console.

Received gas prices: {
  slow: { maxFeePerGas: 26237682174n, maxPriorityFeePerGas: 26237682174n },
  standard: { maxFeePerGas: 27487095611n, maxPriorityFeePerGas: 27487095611n },
  fast: { maxFeePerGas: 28736509048n, maxPriorityFeePerGas: 28736509048n }
}

Submit a transaction from the smart account

Finally, let's submit a transaction from the smart account. We will send a transaction to the 0xd8da6bf26964af9d7eed9e03e53415d37aa96045 (vitalik.eth) address with 0x1234 as example callData. We will also specify the gas price we want to use, which we fetched from the bundler in the previous step.

Underneath the hood, the SmartAccountClient will create a UserOperation instance, request Pimlico paymaster sponsorship, sign it with the smart account's private key, and then submit it to the bundler. The bundler will then query for receipts until it sees the user operation included on-chain.

Add the following to the bottom of index.ts:

const txHash = await smartAccountClient.sendTransaction({
	to: "0xd8da6bf26964af9d7eed9e03e53415d37aa96045",
	value: 0n,
	data: "0x1234",
	maxFeePerGas: gasPrices.fast.maxFeePerGas,
	maxPriorityFeePerGas: gasPrices.fast.maxPriorityFeePerGas,
})
 
console.log(`User operation included: https://sepolia.etherscan.io/tx/${txHash}`)

Let's run this code again with npm start. You should see the transaction hash bundling the user operation on-chain printed to the console.

User operation included: https://sepolia.etherscan.io/tx/0x7a2b61b4b7b6e9e66c459e3c9c24c7a292fc6c740533ce35dbf58710960cc0e5

You can now view the transaction on the Sepolia testnet explorer. By sending this user operation, you have:

  • Deployed the counterfactual smart account contract
  • Had this newly-deployed smart account verify the private key's signature
  • Made Pimlico's verifying paymaster sponsor the user operation's gas fees
  • Executed a simple transaction to vitalik.eth's address

All in a couple lines of code.

Congratulations, you are now a pioneer of Account Abstraction! 🎉

Please get in touch if you have any questions or if you'd like to share what you're building!

Combined code

If you want to see the complete code that combines all of the previous steps, we uploaded it to a separate repository. If you're looking to run it, remember to replace the API key with your own!