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This guide shows how to combine Turnkey and Biconomy AbstractJS to send secure gasless transactions using EIP-7702. You’ll use Turnkey to manage your private keys, and Biconomy to abstract gas via the MEE stack.
1

Install Dependencies

Install core SDKs from Turnkey, Biconomy, and viem.
npm install @turnkey/sdk-server @turnkey/viem @biconomy/abstractjs viem dotenv
2

Configure .env

Store Turnkey credentials and signing key in environment variables.
BASE_URL=https://api.turnkey.com
API_PRIVATE_KEY=your_api_private_key
API_PUBLIC_KEY=your_api_public_key
ORGANIZATION_ID=your_organization_id
SIGN_WITH=your_private_key_id
3

Initialize Turnkey Client

Set up Turnkey client for key management and signing.
import { Turnkey } from "@turnkey/sdk-server";
import * as dotenv from "dotenv";
dotenv.config();

const client = new Turnkey({
  apiBaseUrl: process.env.BASE_URL,
  apiPrivateKey: process.env.API_PRIVATE_KEY,
  apiPublicKey: process.env.API_PUBLIC_KEY,
  defaultOrganizationId: process.env.ORGANIZATION_ID,
});
4

Create Wallet Client

Create a viem wallet client from the Turnkey account.
import { createWalletClient, http } from "viem";
import { createAccount } from "@turnkey/viem";
import { optimism } from "viem/chains";

const account = await createAccount({
  client: client.apiClient(),
  organizationId: process.env.ORGANIZATION_ID,
  signWith: process.env.SIGN_WITH,
});

const walletClient = createWalletClient({
  account,
  chain: optimism,
  transport: http(),
});
5

Sign EIP-7702 Authorization

Sign the delegation message needed to enable smart account functionality on the EOA.
const nexusImplementationAddress = "0x000000004F43C49e93C970E84001853a70923B03";

const authorization = await walletClient.signAuthorization({
  contractAddress: nexusImplementationAddress,
  account,
});
6

Create Nexus Smart Account

Override accountAddress to match the EOA — this activates EIP-7702 delegation.
import { toMultichainNexusAccount, getMEEVersion, MEEVersion } from "@biconomy/abstractjs";
import { base } from "viem/chains";

const nexusAccount = await toMultichainNexusAccount({
  chainConfigurations: [
    {
      chain: optimism,
      transport: http(),
      version: getMEEVersion(MEEVersion.V2_1_0),
      accountAddress: account.address // use EOA for EIP-7702
    },
    {
      chain: base,
      transport: http(),
      version: getMEEVersion(MEEVersion.V2_1_0),
      accountAddress: account.address // use EOA for EIP-7702
    }
  ],
  signer: walletClient
});
7

Create MEE Client

Connect to the Modular Execution Environment for gasless transaction execution.
import { createMeeClient } from "@biconomy/abstractjs";

const meeClient = await createMeeClient({
  account: nexusAccount
});
8

Send Gasless Transaction

Set delegate: true and include authorization to trigger execution via EIP-7702 delegation.
const { hash } = await meeClient.execute({
  authorization,
  delegate: true,
  feeToken: {
    address: "0xYourUSDCAddress",
    chainId: optimism.id,
  },
  instructions: [
    {
      chainId: optimism.id,
      calls: [
        {
          to: "0x0000000000000000000000000000000000000000",
          value: 0n
        }
      ]
    }
  ]
});
9

Cross-Chain Execution (Optional)

Instructions can target multiple chains. Everything is handled by one user signature.
const { hash } = await meeClient.execute({
  authorization,
  delegate: true,
  instructions: [
    {
      chainId: optimism.id,
      calls: [{ to: "0x...", value: 0n }]
    },
    {
      chainId: base.id,
      calls: [{ to: "0x...", value: 0n }]
    }
  ]
});

​
Summary

  • Turnkey securely manages EOA keys
  • Biconomy enables EIP-7702-based smart account delegation
  • Set accountAddress to the EOA address for EIP-7702 flow
  • Use delegate: true + authorization in the execution call
  • MEE handles gas payment using ERC-20s or sponsorship
This setup gives you secure, gas-abstracted, and cross-chain smart account transactions with minimal UX friction.