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Send your first gasless transaction

plug and playaccount abstractionwebpaymastererc4337Web3Auth Team | October 22, 2024

A paymaster is a vital component in the ERC-4337 standard, responsible for covering transaction costs on behalf of the user. There are various types of paymasters, such as gasless paymasters, ERC-20 paymasters, and more.

In this guide, we'll talk about how you can use the Pimlico gasless Paymaster with Web3Auth Account Abstraction Provider to sponsor the transaction for your users without requiring the user to pay gas fees.

For those who want to skip straight to the code, you can find it on GitHub.

Prerequisites​

  • Pimlico Account: Since we'll be using the Pimlico paymaster, you'll need to have an API key from Pimlico. You can get a free API key from Pimlico Dashboard.
  • Web3Auth Dashboard: If you haven't already, sign up on the Web3Auth platform. It is free and gives you access to the Web3Auth's base plan. Head to Web3Auth's documentation page for detailed instructions on setting up the Web3Auth Dashboard.
  • Web3Auth PnP Web SDK: This guide assumes that you already know how to integrate the PnP Web SDK in your project. If not, you can learn how to integrate Web3Auth in your Web app.

Integrate AccountAbstractionProvider​

Once, you have set up the Web3Auth Dashboard, and created a new project, it's time to integrate Web3Auth Account Abstraction Provider in your Web application. For the implementation, we'll use the @web3auth/account-abstraction-provider. The provider simplifies the entire process by managing the complex logic behind configuring the account abstraction provider, bundler, and preparing user operations.

If you are already using the Web3Auth Pnp SDK in your project, you just need to configure the AccountAbstractionProvider with the paymaster details, and pass it to the Web3Auth instance. No other changes are required.

Installation​

npm install --save @web3auth/account-abstraction-provider

Configure Paymaster​

The AccountAbstractionProvider requires specific configurations to function correctly. One key configuration is the paymaster. Web3Auth supports custom paymaster configurations, allowing you to deploy your own paymaster and integrate it with the provider.

You can choose from a variety of paymaster services available in the ecosystem. In this guide, we'll be configuring the Pimlico's paymaster. However, it's important to note that paymaster support is not limited to the Pimlico, giving you the flexibility to integrate any compatible paymaster service that suits your requirements.

For the simplicity, we have only use SafeSmartAccount, but you choose your favorite smart account provider from the available ones. Learn how to configure the smart account.

import {
  AccountAbstractionProvider,
  SafeSmartAccount,
} from "@web3auth/account-abstraction-provider";

const chainConfig = {
  chainNamespace: CHAIN_NAMESPACES.EIP155,
  chainId: "0xaa36a7",
  rpcTarget: "https://rpc.ankr.com/eth_sepolia",
  displayName: "Ethereum Sepolia Testnet",
  blockExplorerUrl: "https://sepolia.etherscan.io",
  ticker: "ETH",
  tickerName: "Ethereum",
  logo: "https://cryptologos.cc/logos/ethereum-eth-logo.png",
};

const accountAbstractionProvider = new AccountAbstractionProvider({
  config: {
    chainConfig,
    bundlerConfig: {
      // Get the pimlico API Key from dashboard.pimlico.io
      url: `https://api.pimlico.io/v2/${chainId}/rpc?apikey=${pimlicoAPIKey}`,
    },
    smartAccountInit: new SafeSmartAccount(),
    paymasterConfig: {
      // Get the pimlico API Key from dashboard.pimlico.io
      url: `https://api.pimlico.io/v2/${chainId}/rpc?apikey=${pimlicoAPIKey}`,
    },
  },
});

Configure Web3Auth​

Once you have configured your AccountAbstractionProvider, you can now plug it in your Web3Auth Modal/No Modal instance. If you are using the external wallets like MetaMask, Coinbase, etc, you can define whether you want to use the AccountAbstractionProvider, or EthereumPrivateKeyProvider by setting the useAAWithExternalWallet in IWeb3AuthCoreOptions.

If you are setting useAAWithExternalWallet to true, it'll create a new Smart Account for your user, where the signer/creator of the Smart Account would be the external wallet.

If you are setting useAAWithExternalWallet to false, it'll skip creating a new Smart Account, and directly use the external wallet to sign the transactions.

import { EthereumPrivateKeyProvider } from "@web3auth/ethereum-provider";
import { Web3Auth } from "@web3auth/modal";

const privateKeyProvider = new EthereumPrivateKeyProvider({
  // Use the chain config we declared earlier
  config: { chainConfig },
});

const web3auth = new Web3Auth({
  clientId: "YOUR_WEB3AUTH_CLIENT_ID",
  web3AuthNetwork: WEB3AUTH_NETWORK.SAPPHIRE_MAINNET,
  privateKeyProvider,
  // Use the account abstraction provider we configured earlier
  accountAbstractionProvider
  // This will allow you to use EthereumPrivateKeyProvider for
  // external wallets, while use the AccountAbstractionProvider
  // for Web3Auth embedded wallets.
  useAAWithExternalWallet: false,
});

Configure Signer​

The Web3Auth AccountAbstractionProvider is compatible with popular signer SDKs, including ethers, web3, and viem. You can choose your preferred package to configure the signer.

You can retreive the provider to configure the signer from Web3Auth instance.

import { createWalletClient } from "viem";

// Use your Web3Auth instance to retreive the provider.
const provider = web3auth.provider;

const walletClient = createWalletClient({
  transport: custom(provider),
});

Send a transaction​

You can use your signer to submit on-chain transactions, while the Account Abstraction Provider handles the creation and submission of the UserOperation. You only need to pass to, data, and value; other parameters will be discarded and overridden by the provider.

The bundler client determines maxFeePerGas and maxPriorityFeePerGas to prevent transaction rejections. If you'd like to specify custom values, you can use AccountAbstractionProvider.bundlerClient to create and send the transaction.

Smart Accounts are basically smart contract deployed on chain. Therefore, the user's first transaction also deploys the smart contract for their wallet.

// Convert 1 ether to WEI format
const amount = parseEther("1");

// Submits a user operation to the blockchain
const hash = await walletClient.sendTransaction({
  to: "DESTINATION_ADDRESS",
  value: amount,
  // This will perform the transfer of ETH
  data: "0x",
});

// Wait for the transaction to be mined
const receipt = await publicClient.waitForTransactionReceipt({ hash });

Conclusion​

Voila, you have successfully sent your first gasless transaction using the Pimlico paymaster with Web3Auth Account Abstraction Provider. To learn more about advance features of the Account Abstraction Provider like performing batch transactions, using ERC-20 paymaster you can refer to the Account Abstraction Provider documentation.