An example of ERC 4337 transaction using viem SDK and Biconomy bundler and paymaster

viem-bico-intergation.ts

import { createPublicClient, http, parseEther } from 'viem';
import { createBundlerClient, toCoinbaseSmartAccount, createPaymasterClient, toSoladySmartAccount } from 'viem/account-abstraction';
import { sepolia } from 'viem/chains';
import { privateKeyToAccount } from 'viem/accounts';

const main = async () => {
  const client = createPublicClient({
    chain: sepolia,
    transport: http(),
  })

  const owner = privateKeyToAccount('PRIVATE_KEY')
  console.log(owner.address)

  const account = await toCoinbaseSmartAccount({
    client,
    owners: [owner]
  })

  const paymasterClient = createPaymasterClient({
    transport: http('BICONOMY_PAYMASTER_URL'),
  })

  const bundlerClient = createBundlerClient({
    account,
    client,
    paymasterContext: {
        "mode": "SPONSORED",
        "calculateGasLimits": true,
        "expiryDuration": 300, // duration (secs) for which the generate paymasterAndData will be valid. Default duration is 300 secs.
        "sponsorshipInfo": {
          "webhookData": {},
          "smartAccountInfo": {
              "name": "BICONOMY",
              "version": "2.0.0"
          }
        }
    },
    paymaster: paymasterClient,
    transport: http('https://bundler.biconomy.io/api/v2/11155111/nJPK7B3ru.dd7f7861-190d-41bd-af80-6877f74b8f44'),
  })

  console.log(account.address);

  const userOpHash = await bundlerClient.sendUserOperation({
    account,
    calls: [{
      to: '0xcb98643b8786950F0461f3B0edf99D88F274574D',
      value: parseEther('0.001')
    }]
  })
  console.log(userOpHash)
}

main()