Send a gasless transaction

MetaMask Smart Accounts support gas sponsorship, which simplifies onboarding by abstracting gas fees away from end users. You can use any paymasterPaymaster A service that pays for user operations on behalf of a smart account. service provider, such as Pimlico or ZeroDev, or plug in your own custom paymaster.

Prerequisites

• Install and set up the Smart Accounts Kit.
• Create a MetaMask smart account.

Send a gasless transaction

The following example demonstrates how to use Viem's Paymaster Client to send gasless transactions. You can provide the paymaster client using the paymaster property in the sendUserOperation method, or in the Bundler Client.

In this example, the paymaster client is passed to the sendUserOperation method.

example.ts

import { bundlerClient, smartAccount, paymasterClient } from './config.ts'
import { parseEther } from 'viem'

// Appropriate fee per gas must be determined for the specific bundler being used.
const maxFeePerGas = 1n
const maxPriorityFeePerGas = 1n

const userOperationHash = await bundlerClient.sendUserOperation({
  account: smartAccount,
  calls: [
    {
      to: '0x1234567890123456789012345678901234567890',
      value: parseEther('0.001'),
    },
  ],
  maxFeePerGas,
  maxPriorityFeePerGas,
  paymaster: paymasterClient,
})

config.ts

import { createPublicClient, createPaymasterClient, http } from 'viem'
import { createBundlerClient } from 'viem/account-abstraction'
import { sepolia as chain } from 'viem/chains'
import { generatePrivateKey, privateKeyToAccount } from 'viem/accounts'
import { Implementation, toMetaMaskSmartAccount } from '@metamask/smart-accounts-kit'

const publicClient = createPublicClient({
  chain,
  transport: http(),
})

const privateKey = generatePrivateKey()
const account = privateKeyToAccount(privateKey)

export const smartAccount = await toMetaMaskSmartAccount({
  client: publicClient,
  implementation: Implementation.Hybrid,
  deployParams: [account.address, [], [], []],
  deploySalt: '0x',
  signer: { account },
})

export const bundlerClient = createBundlerClient({
  client: publicClient,
  transport: http('https://api.pimlico.io/v2/11155111/rpc?apikey=<YOUR-API-KEY>'),
})

export const paymasterClient = createPaymasterClient({
  // You can use the paymaster of your choice
  transport: http('https://api.pimlico.io/v2/11155111/rpc?apikey=<YOUR-API-KEY>'),
})