Biconomy Integration with Metal L2 Testnet

In this tutorial, we'll walk through the process of integrating Biconomy with Metal L2 Testnet chain to enable gasless transactions.

The tutorial covers the entire process from setting up the Biconomy paymaster to actually sending a gasless transaction on the Metal L2 Testnet chain.

Prerequisites

A wallet with some testnet tokens for Metal L2 Testnet

Step 1: Create a Biconomy Paymaster

Go to the Biconomy Dashboard (opens in a new tab).
Sign up or log in to your account.
Click on "Create New Paymaster."
Select "Metal L2 Testnet" as the network.
Choose a name for your paymaster and click "Create."
Once created, you'll see your Paymaster API Key. Save this for later use.

Step 2: Create a Smart Account

Install the necessary dependencies:

npm install @biconomy/account viem

Set up your account and biconomy configuration:

import { createWalletClient, http, parseEther } from "viem";
import { privateKeyToAccount } from "viem/accounts";
import { createSmartAccountClient, PaymasterMode, getCustomChain } from "@biconomy/account";
 
const config = {
    privateKey: "your-private-key",
    biconomyPaymasterApiKey: "your-paymaster-api-key",
    bundlerUrl: "https://bundler.biconomy.io/api/v2/1802203764/nJPK7B3ru.dd7f7861-190d-41bd-af80-6877f74b8f44",
    explorerUrl: "https://testnet.explorer.metall2.com"
};

Create a Biconomy Smart Account:

const account = privateKeyToAccount(`0x${config.privateKey}`);
const customChain = getCustomChain(
        "Metal L2 Testnet",
        config.chainId,
        config.providerUrl,
        config.explorerUrl
      );
const client = createWalletClient({
    account,
    chain: customChain,
    transport: http(),
});
 
const smartWallet = await createSmartAccountClient({
    signer: client,
    biconomyPaymasterApiKey: config.biconomyPaymasterApiKey,
    bundlerUrl: config.bundlerUrl,
});
const saAddress = await smartWallet.getAccountAddress();
console.log("Smart Account Address", saAddress);

Step 3: Send a Gasless Transaction

Prepare the transaction data:

const tx = {
    to: '0xf5715961C550FC497832063a98eA34673ad7C816',
    value: parseEther('0.0001')
};
console.log("Transaction sent:", tx);

Send the transaction and wait for the result:

const userOpResponse = await smartWallet.sendTransaction(tx, {
    paymasterServiceData: { mode: PaymasterMode.SPONSORED },
});
const { transactionHash } = await userOpResponse.waitForTxHash();
console.log("Transaction Hash", transactionHash);
const userOpReceipt = await userOpResponse.wait();
if (userOpReceipt.success === "true") {
    console.log("UserOp receipt", userOpReceipt);
    console.log("Transaction receipt", userOpReceipt.receipt);
}

Conclusion

You have now successfully integrated Biconomy with Metal L2 Testnet chain and sent a gasless transaction. This setup allows your users to interact with your dApp without worrying about gas fees, improving the overall user experience.

Remember to handle errors appropriately and consider implementing additional features like transaction status updates or retry mechanisms for failed transactions.

For more advanced use cases and detailed documentation, refer to the Biconomy documentation (opens in a new tab).

Networks and RPC Endpoints Contract Addresses