Pimlico AA Infrastructure Integration

Integration with Pimlico (AA Infrastructure)

Pimlico is infrastructure provider for Account Abstraction: bundler (packs UserOperations into transactions) and paymaster (sponsors gas). This is managed service on top of ERC-4337, which removes need to run own bundler and manage paymaster contract.

What Pimlico Provides

Bundler API — accepts UserOperations, validates, packs into bundle transactions and sends on-chain. Supports eth_sendUserOperation, eth_estimateUserOperationGas, eth_getUserOperationByHash — standard ERC-4337 interface.

Paymaster API — sponsoring gas without needing ETH on user wallet. Two modes: verifying paymaster (signs permission to sponsor specific operation) and ERC-20 paymaster (user pays gas in USDC/other token).

Alto — Pimlico's open-source bundler, which can be deployed independently if you need independence from their infrastructure.

Integration via permissionless.js

Pimlico supports permissionless.js — TypeScript library for working with AA:

import { createSmartAccountClient } from "permissionless";
import { createPimlicoBundlerClient, createPimlicoPaymasterClient } from "permissionless/clients/pimlico";
import { createPublicClient, http } from "viem";
import { sepolia } from "viem/chains";

const publicClient = createPublicClient({
  chain: sepolia,
  transport: http("https://rpc.ankr.com/eth_sepolia"),
});

const bundlerClient = createPimlicoBundlerClient({
  transport: http(`https://api.pimlico.io/v2/sepolia/rpc?apikey=${PIMLICO_API_KEY}`),
  entryPoint: ENTRYPOINT_ADDRESS_V07,
});

const paymasterClient = createPimlicoPaymasterClient({
  transport: http(`https://api.pimlico.io/v2/sepolia/rpc?apikey=${PIMLICO_API_KEY}`),
  entryPoint: ENTRYPOINT_ADDRESS_V07,
});

Creating smart account (based on Safe or Kernel):

import { signerToSafeSmartAccount } from "permissionless/accounts";

const safeAccount = await signerToSafeSmartAccount(publicClient, {
  signer: walletClient,
  entryPoint: ENTRYPOINT_ADDRESS_V07,
  safeVersion: "1.4.1",
});

const smartAccountClient = createSmartAccountClient({
  account: safeAccount,
  entryPoint: ENTRYPOINT_ADDRESS_V07,
  chain: sepolia,
  bundlerTransport: http(`https://api.pimlico.io/v2/sepolia/rpc?apikey=${API_KEY}`),
  middleware: {
    sponsorUserOperation: paymasterClient.sponsorUserOperation,
  },
});

// Send transaction without ETH on wallet
const txHash = await smartAccountClient.sendTransaction({
  to: "0xTarget",
  value: 0n,
  data: "0xCalldata",
});

Paymaster Integration

For sponsored transactions — paymaster signs permission to sponsor specific UserOperation:

// Getting sponsorship from Pimlico
const sponsorResult = await paymasterClient.sponsorUserOperation({
  userOperation: userOp,
});

// sponsorResult contains:
// - paymasterAndData (for EntryPoint V0.6)
// - paymaster + paymasterData + paymasterVerificationGasLimit + paymasterPostOpGasLimit (V0.7)

ERC-20 paymaster allows users to pay gas in USDC. Pimlico supports this via pimlicoPaymasterClient.getTokenQuotes to get rate and approveTokenPaymaster to approve token.

Limits and Pricing

Pimlico works on freemium model: free tier with limits on number of UserOperations per day. Production requires API key with per-operation payment or fixed plan. When choosing paymaster — Pimlico charges commission on top of actual gas cost.

Integration timeline of basic AA flow with Pimlico bundler and paymaster — 1-2 weeks. Includes smart account implementation choice (Safe, Kernel, Biconomy), paymaster policy setup, testnet testing.