3rd party smart contracts

You aren't limited to the accounts defined in @alchemy/smart-accounts. If you'd like to bring your own smart account, you have two options:

1. Use any library that returns a viem-compatible SmartAccount — those plug into the same createBundlerClient flow we use for Light Account and Modular Account V2.
2. Build your own SmartAccount implementation with viem's toSmartAccount primitive.

Using a third-party SmartAccount

Any object that satisfies viem's SmartAccount interface works:

import { createBundlerClient } from "viem/account-abstraction";
import { createClient } from "viem";
import { sepolia } from "viem/chains";
import { alchemyTransport } from "@alchemy/common";
import { estimateFeesPerGas } from "@alchemy/aa-infra";
import { myAccount } from "./my-account"; // your custom SmartAccount
 
const transport = alchemyTransport({ apiKey: "your-api-key" });
const rpcClient = createClient({ chain: sepolia, transport });
 
const bundlerClient = createBundlerClient({
  account: myAccount,
  client: rpcClient,
  chain: sepolia,
  transport,
  userOperation: { estimateFeesPerGas },
});
 
const hash = await bundlerClient.sendUserOperation({
  calls: [{ to: "0x0000000000000000000000000000000000000000", value: 0n, data: "0x" }],
});

Building a custom SmartAccount

Use toSmartAccount from viem/account-abstraction. You provide:

• The entry point version your account uses (0.6, 0.7, or 0.8).
• getAddress() — counterfactual or deployed address.
• getFactoryArgs() — factory address + calldata (for first-time deploys).
• encodeCalls() — encode one or more calls into your account's execution calldata.
• signUserOperation() / signMessage / signTypedData — signing methods bound to your account's owner.

The viem docs walk through a full custom example. Once you have a SmartAccount, pass it to createBundlerClient exactly like the snippet above.

Why use the existing implementations?

@alchemy/smart-accounts ships viem-compatible implementations of Light Account, Modular Account V1, and Modular Account V2, plus the validation/permission builders for MAv2. If your use case fits one of those, you'll save a lot of custom-account boilerplate.

Using Alchemy smart accounts with third-party infrastructure

If you want to keep Alchemy's smart account implementations while using non-Alchemy infrastructure, see the low-level infrastructure guides:

• Non-Alchemy chains — run @alchemy/smart-accounts on a chain Alchemy doesn't support.
• Third-party bundlers — submit user operations through another bundler RPC.
• Third-party paymasters — sponsor user operations with a non-Alchemy paymaster.