Account Abstraction SDK (aa-sdk)

⚠️ This repo is actively being developed and certain features might not be fully implemented yet or are subject to change ⚠️

Alchemy's Account Abstraction Kit is an SDK that enables easy interactions with ERC-4337 compliant smart accounts. It supports bringing your own Account Contracts or using any of the currently available accounts. The SDK is built on top of viem to enable a lighter-weight bundle and is published with ESM default exports though also supports CJS.

Getting Started

via yarn:

yarn add @alchemy/aa-core viem

via npm:

npm i -s @alchemy/aa-core viem

If you are using Alchemy APIs for Account Abstraction, then you can also add the @alchemy/aa-alchemy package:

via yarn:

yarn add @alchemy/aa-alchemy

via npm:

npm i -s @alchemy/aa-alchemy

If you are using ethers and want to use an ethers compatible Provider and Signer you can also add the the @alchemy/aa-ethers library (the above packages are required still).

via yarn:

yarn add @alchemy/aa-ethers

via npm:

npm i -s @alchemy/aa-ethers

Example Usage to Interact with Simple Accounts

Note 🗒️: We've also included an E2E example here. This example DApp creates a simple account wallet and mints an NFT in one flow.

via aa-core

import {
  SimpleSmartContractAccount,
  SmartAccountProvider,
  type SmartAccountSigner,
  LocalAccountSigner,
} from "@alchemy/aa-core";
import { mnemonicToAccount } from "viem/accounts";
import { polygonMumbai } from "viem/chains";
import { toHex } from "viem";

const SIMPLE_ACCOUNT_FACTORY_ADDRESS =
  "0x9406Cc6185a346906296840746125a0E44976454";

// 1. define the EOA owner of the Smart Account
// this uses a utility method for creating an account signer using mnemonic
// we also have a utility for creating an account signer from a private key
const owner: SmartAccountSigner =
  LocalAccountSigner.mnemonicToAccountSigner(MNEMONIC);

// 2. initialize the provider and connect it to the account
const provider = new SmartAccountProvider({
  // the demo key below is public and rate-limited, it's better to create a new one
  // you can get started with a free account @ https://www.alchemy.com/
  rpcProvider: "https://polygon-mumbai.g.alchemy.com/v2/demo",
  entryPointAddress: "0x5FF137D4b0FDCD49DcA30c7CF57E578a026d2789",
  chain: polygonMumbai,
}).connect(
  (rpcClient) =>
    new SimpleSmartContractAccount({
      entryPointAddress: "0x5FF137D4b0FDCD49DcA30c7CF57E578a026d2789",
      chain: polygonMumbai,
      factoryAddress: SIMPLE_ACCOUNT_FACTORY_ADDRESS,
      rpcClient,
      owner,
      // optionally if you already know the account's address
      accountAddress: "0x000...000",
    })
);

// 3. send a UserOperation
const { hash } = await provider.sendUserOperation({
  target: "0xTargetAddress",
  data: "0xcallData",
  value: 0n, // value: bigint or undefined
});

via aa-alchemy

import {
  SimpleSmartContractAccount,
  type SmartAccountSigner,
  LocalAccountSigner,
} from "@alchemy/aa-core";
import { toHex } from "viem";
import { mnemonicToAccount } from "viem/accounts";
import { polygonMumbai } from "viem/chains";
import { AlchemyProvider } from "@alchemy/aa-alchemy";

const SIMPLE_ACCOUNT_FACTORY_ADDRESS =
  "0x9406Cc6185a346906296840746125a0E44976454";

// 1. define the EOA owner of the Smart Account
// this uses a utility method for creating an account signer using mnemonic
// we also have a utility for creating an account signer from a private key
const owner: SmartAccountSigner =
  LocalAccountSigner.mnemonicToAccountSigner(MNEMONIC);

// 2. initialize the provider and connect it to the account
let provider = new AlchemyProvider({
  apiKey: API_KEY,
  chain,
  entryPointAddress: ENTRYPOINT_ADDRESS,
}).connect(
  (rpcClient) =>
    new SimpleSmartContractAccount({
      entryPointAddress: ENTRYPOINT_ADDRESS,
      chain: polygonMumbai, // ether a viem Chain or chainId that supports account abstraction at Alchemy
      owner,
      factoryAddress: SIMPLE_ACCOUNT_FACTORY_ADDRESS,
      rpcClient,
    })
);

// [OPTIONAL] Use Alchemy Gas Manager
provider = provider.withAlchemyGasManager({
  policyId: PAYMASTER_POLICY_ID,
  entryPoint: ENTRYPOINT_ADDRESS,
});

// 3. send a UserOperation
const { hash } = await provider.sendUserOperation({
  target: "0xTargetAddress",
  data: "0xcallData",
  value: 0n, // value: bigint or undefined
});

via aa-ethers

import {
  alchemyPaymasterAndDataMiddleware,
  getChain,
  SimpleSmartContractAccount,
} from "@alchemy/aa-core";
import { Alchemy, Network } from "alchemy-sdk";
import { Wallet } from "@ethersproject/wallet";
import {
  EthersProviderAdapter,
  convertWalletToAccountSigner,
} from "@alchemy/aa-ethers";

const SIMPLE_ACCOUNT_FACTORY_ADDRESS =
  "0x9406Cc6185a346906296840746125a0E44976454";

// 1. connect to an RPC Provider and a Wallet
const alchemy = new Alchemy({
  apiKey: API_KEY,
  network: Network.MATIC_MUMBAI,
});
const alchemyProvider = await alchemy.config.getProvider();
const owner = Wallet.fromMnemonic(MNEMONIC);

// 2. Create the SimpleAccount signer
// signer is an ethers.js Signer
const signer = EthersProviderAdapter.fromEthersProvider(
  alchemyProvider,
  ENTRYPOINT_ADDRESS
).connectToAccount(
  (rpcClient) =>
    new SimpleSmartContractAccount({
      entryPointAddress: ENTRYPOINT_ADDRESS,
      chain: getChain(alchemyProvider.network.chainId),
      owner: convertWalletToAccountSigner(owner),
      factoryAddress: SIMPLE_ACCOUNT_FACTORY_ADDRESS,
      rpcClient,
    })
);

// 3. send a user op
const { hash } = await signer.sendUserOperation({
  target: "0xTargetAddress",
  data: "0xcallData",
  value: 0n, // value: bigint or undefined
});

Components

Core Components

The primary interfaces are the SmartAccountProvider and BaseSmartContractAccount.

The SmartAccountProvider is an ERC-1193 compliant Provider that wraps JSON RPC methods and some Wallet Methods (signing, sendTransaction, etc). It also provides two utility methods for sending UserOperations:

1. sendUserOperation -- this takes in target, callData, and an optional value which then constructs a UserOperation (UO), sends it, and returns the hash of the UO. It handles estimating gas, fetching fee data, (optionally) requesting paymasterAndData, and lastly signing. This is done via a middleware stack that runs in a specific order. The middleware order is getDummyPaymasterData => estimateGas => getFeeData => getPaymasterAndData. The paymaster fields are set to 0x by default. They can be changed using provider.withPaymasterMiddleware.
2. sendTransaction -- this takes in a traditional Transaction Request object which then gets converted into a UO. Currently, the only data being used from the Transaction Request object is from, to, data and value. Support for other fields is coming soon.

If you want to add support for your own SmartAccounts then you will need to provide an implementation of BaseSmartContractAccount. You can see an example of this in SimpleSmartContractAccount. You will need to implement 4 methods:

1. getDummySignature -- this method should return a signature that will not revert during validation. It does not have to pass validation, just not cause the contract to revert. This is required for gas estimation so that the gas estimate are accurate.
2. encodeExecute -- this method should return the abi encoded function data for a call to your contract's execute method
3. signMessage -- this should return an ERC-191 compliant message and is used to sign UO Hashes
4. getAccountInitCode -- this should return the init code that will be used to create an account if one does not exist. Usually this is the concatenation of the account's factory address and the abi encoded function data of the account factory's createAccount method.

Paymaster Middleware

You can use provider.withPaymasterMiddleware to add middleware to the stack which will set the paymasterAndData field during sendUserOperation calls. The withPaymasterMiddleware method has two overrides. One of the overrides takes a dummyPaymasterData generator function. This dummyPaymasterData is needed to estimate gas correctly when using a paymaster and is specific to the paymaster you're using. The second override is the actually paymasterAndData generator function. This function is called after gas estimation and fee estimation and is used to set the paymasterAndData field. The default dummyPaymasterData generator function returns 0x for both the paymasterAndData fields. The default paymasterAndData generator function returns 0x for both the paymasterAndData fields.

Both of the override methods can return new gas estimates. This allows for paymaster RPC urls that handle gas estimation for you. It's important to note that if you're using an ERC-20 paymaster and your RPC endpoint does not return estimates, you should add an additional 75k gas to the gas estimate for verificationGasLimit.

Alchemy Gas Manager Middleware

Alchemy has two separate RPC methods for interacting with our Gas Manager services. The first is alchemy_requestPaymasterAndData and the second is alchemy_requestGasAndPaymasterAndData. The former is useful if you want to do your own gas estimation + fee estimation (or you're happy using the default middlewares for gas and fee estimation), but want to use the Alchemy Gas Manager service. The latter is will handle gas + fee estimation and return paymasterAndData in a single request.

We provide two utility methods in @alchemy/aa-alchemy for interacting with these RPC methods:

1. alchemyPaymasterAndDataMiddleware which is used in conjunction with withPaymasterMiddleware to add the alchemy_requestPaymasterAndData RPC method to the middleware stack.
2. withAlchemyGasManager which wraps a connected SmartAccountProvider with the middleware overrides to use alchemy_requestGasAndPaymasterAndData RPC method.

Contributing

1. clone the repo
2. run yarn
3. Make changes to packages

To run tests:

TODO: currently tests require a specific mnemonic to pass and they run against the alchemy bundler which is in private beta.