How to create and use a Safe account with permissionless.js

Safe is the most battle-tested Ethereum smart account provider. With their recent release of their ERC-4337 module, it is now possible to plug in Safe accounts to ERC-4337 bundlers and paymasters. This guide will walk you through how to create and use a Safe account with permissionless.js.

Steps

Import the required packages

import { ENTRYPOINT_ADDRESS_V07, createSmartAccountClient } from "permissionless"
import { signerToSafeSmartAccount } from "permissionless/accounts"
import {
	createPimlicoBundlerClient,
	createPimlicoPaymasterClient,
} from "permissionless/clients/pimlico"
import { createPublicClient, getContract, http, parseEther } from "viem"
import { sepolia } from "viem/chains"

Create the clients

First we must create the public, bundler, and (optionally) paymaster clients that will be used to interact with the Safe account.

export const publicClient = createPublicClient({
	transport: http("https://rpc.ankr.com/eth_sepolia"),
})
 
export const paymasterClient = createPimlicoPaymasterClient({
	transport: http("https://api.pimlico.io/v2/sepolia/rpc?apikey=API_KEY"),
	entryPoint: ENTRYPOINT_ADDRESS_V07,
})
 
export const pimlicoBundlerClient = createPimlicoBundlerClient({
	transport: http("https://api.pimlico.io/v2/sepolia/rpc?apikey=API_KEY"),
	entryPoint: ENTRYPOINT_ADDRESS_V07,
})

Create the signer

The Safe account will need to have a signer to sign user operations. In permissionless.js, the default Safe account validates ECDSA signatures. Any permissionless.js-compatible signer can be used for the Safe account.

For example, to create a signer based on a private key:

import { privateKeyToAccount } from "viem/accounts"
 
const signer = privateKeyToAccount("0xPRIVATE_KEY")

Create the Safe account

With a signer, you can create a Safe account as such:

const safeAccount = await signerToSafeSmartAccount(publicClient, {
	entryPoint: ENTRYPOINT_ADDRESS_V07,
	signer: signer,
	saltNonce: 0n, // optional
	safeVersion: "1.4.1",
	address: "0x...", // optional, only if you are using an already created account
})

Create the smart account client

The smart account client is a permissionless.js client that is meant to serve as an almost drop-in replacement for viem's walletClient.

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, // optional
		gasPrice: async () => (await pimlicoBundlerClient.getUserOperationGasPrice()).fast, // if using pimlico bundler
	},
})

Send a transaction

Transactions using permissionless.js simply wrap around user operations. This means you can switch to permissionless.js from your existing viem EOA codebase with minimal-to-no changes.

const txHash = await smartAccountClient.sendTransaction({
	to: "0xd8da6bf26964af9d7eed9e03e53415d37aa96045",
	value: parseEther("0.1"),
})

This also means you can also use viem Contract instances to transact without any modifications.

const nftContract = getContract({
	address: "0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2",
	abi: nftAbi,
	client: {
		public: publicClient,
		wallet: smartAccountClient,
	},
})
 
const txHash = await nftContract.write.mint()

You can also send an array of transactions in a single batch.

const txHash = await smartAccountClient.sendTransactions({
	transactions: [
		{
			to: "0xd8da6bf26964af9d7eed9e03e53415d37aa96045",
			value: parseEther("0.1"),
			data: "0x",
		},
		{
			to: "0x1440ec793aE50fA046B95bFeCa5aF475b6003f9e",
			value: parseEther("0.1"),
			data: "0x1234",
		},
	],
})

Understanding the errors

If you're getting an error that starts with GS, it probably means that something went off with the Safe account. Checkout the Safe error codes here.