privy-permissionless-7702

In this guide, we'll demonstrate how to use Pimlico, a bundler and paymaster service for ERC-4337 accounts, together with Privy to enable your users to send gasless (sponsored) transactions using EIP-7702 authorization.

Want to see a full end to end example? Check out our starter repo here!

0. Install dependencies

In your app's repository, install the required dependencies from Privy, Permissionless, and Viem:

npm i @privy-io/react-auth @privy-io/wagmi permissionless viem wagmi

1. Sign up for a Pimlico account and get your API key

Head to the Pimlico dashboard and create an account. Generate an API key and create a sponsorship policy for the network you plan to use (optional). Make note of your API key and sponsorship policy ID.

2. Configure Privy settings

Configure your app to create embedded wallets for all users.

<PrivyProvider
  config={{
    embeddedWallets: {
      createOnLogin: 'all-users'
      showWalletUIs: true
    }
  }}
>
  ...
</PrivyProvider>

3. Create a simple smart account with Permissionless SDK

Permissionless provides a simple way to create a smart account client that can send user operations with EIP-7702 authorization. All you need is the user's embedded wallet and the Pimlico API key.

import { usePrivy, useSignAuthorization, useWallets } from "@privy-io/react-auth"
import { useSetActiveWallet } from "@privy-io/wagmi"
import { useWalletClient } from "wagmi"
import { createPublicClient, createWalletClient, http, zeroAddress } from "viem"
import { sepolia } from "viem/chains"
import { createSmartAccountClient } from "permissionless"
import { createPimlicoClient } from "permissionless/clients/pimlico"
import { entryPoint08Address } from "viem/account-abstraction"
import { toSimpleSmartAccount } from "permissionless/accounts"

// Get the Privy embedded wallet
const { wallets } = useWallets()
const { data: walletClient } = useWalletClient()
const embeddedWallet = wallets.find((wallet) => wallet.walletClientType === "privy")

// Set the embedded wallet as active
const { setActiveWallet } = useSetActiveWallet()
useEffect(() => {
  if (embeddedWallet) {
    setActiveWallet(embeddedWallet)
  }
}, [embeddedWallet, setActiveWallet])

// Create a public client for the chain
const publicClient = createPublicClient({
  chain: sepolia,
  transport: http(process.env.NEXT_PUBLIC_SEPOLIA_RPC_URL)
})

// Create a Pimlico client
const pimlicoApiKey = process.env.NEXT_PUBLIC_PIMLICO_API_KEY
const pimlicoUrl = `https://api.pimlico.io/v2/sepolia/rpc?apikey=${pimlicoApiKey}`
const pimlicoClient = createPimlicoClient({
  transport: http(pimlicoUrl)
})

// Create a simple smart account
const simpleSmartAccount = await toSimpleSmartAccount({
  owner: walletClient,
  entryPoint: {
    address: entryPoint08Address,
    version: "0.8"
  },
  client: publicClient,
  address: walletClient.account.address
})

// Create the smart account client
const smartAccountClient = createSmartAccountClient({
  account: simpleSmartAccount,
  chain: sepolia,
  bundlerTransport: http(pimlicoUrl),
  paymaster: pimlicoClient,
  userOperation: {
    estimateFeesPerGas: async () => {
      return (await pimlicoClient.getUserOperationGasPrice()).fast
    }
  }
})

4. Sign the EIP-7702 authorization

Privy provides a useSignAuthorization hook that allows you to sign an EIP-7702 authorization using the user's embedded wallet. This authorization is a cryptographic signature that allows an EOA to set its code to that of a smart contract, enabling the EOA to behave like a smart account.

const { signAuthorization } = useSignAuthorization()

// Sign the EIP-7702 authorization
const authorization = await signAuthorization({
  contractAddress: "0xe6Cae83BdE06E4c305530e199D7217f42808555B", // Simple account implementation address
  chainId: sepolia.id,
  nonce: await publicClient.getTransactionCount({
    address: walletClient.account.address
  })
})

5. Send a gas-sponsored transaction

With the smart account client configured and the authorization signed, you can now send gasless UserOperations. Below we send an empty call to the zero address:

const txnHash = await smartAccountClient.sendTransaction({
  calls: [
    {
      to: zeroAddress,
      data: "0x",
      value: BigInt(0)
    }
  ],
  factory: '0x7702',
  factoryData: '0x',
  paymasterContext: {
    sponsorshipPolicyId: process.env.NEXT_PUBLIC_SPONSORSHIP_POLICY_ID
  },
  authorization
})

console.log(`Transaction hash: ${txnHash}`)
console.log(`View on Etherscan: https://sepolia.etherscan.io/tx/${txnHash}`)

Conclusion

That's it! You've just executed a gasless transaction from a normal EOA upgraded with EIP-7702 using Pimlico as the bundler and paymaster service.

Explore the rest of the Pimlico docs to learn about advanced features like batching transactions, gas estimation, and more.

Want to see a full end to end example? Check out our starter repo here!