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 { createSmartAccountClient } from "permissionless"
import { createPublicClient, getContract, http, parseEther } from "viem"
import { sepolia } from "viem/chains"

Create the clients

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

export const publicClient = createPublicClient({
	chain: sepolia,
	transport: http("https://rpc.ankr.com/eth_sepolia"),
})
 
export const paymasterClient = createPimlicoClient({
	transport: http("https://api.pimlico.io/v2/sepolia/rpc?apikey=API_KEY"),
	entryPoint: {
		address: entryPoint07Address,
		version: "0.7",
	},
})

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"
import { createPimlicoClient } from "permissionless/clients/pimlico"
import { entryPoint07Address } from "viem/account-abstraction"
import { toSafeSmartAccount } from "permissionless/accounts"
 
const owner = privateKeyToAccount("0xPRIVATE_KEY")

Create the Safe account

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

const safeAccount = await toSafeSmartAccount({
	client: publicClient,
	entryPoint: {
		address: entryPoint07Address,
		version: "0.7",
	},
	owners: [owner],
	saltNonce: 0n, // optional
	version: "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,
	chain: sepolia,
	paymaster: paymasterClient,
	bundlerTransport: http("https://api.pimlico.io/v2/sepolia/rpc?apikey=API_KEY"),
	userOperation: {
		estimateFeesPerGas: async () => (await paymasterClient.getUserOperationGasPrice()).fast,
	},
})

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 userOpHash = await smartAccountClient.sendUserOperation({
	calls: [
		{
			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.