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Sending Gasless Transactions with SDK ⚡️

Gasless transactions enable users to interact with the blockchain without paying for gas fees. This is achieved through the use of a paymaster, which sponsors the transaction fees on behalf of the user. In this tutorial, we will guide you through the process of sending gasless transactions using the SDK.

Set up an owner account

First, we need to set up an Owner for the Smart Account which will be used to sign User Operations (transactions) for the Smart Account.

import { privateKeyToAccount, generatePrivateKey } from "viem/accounts";
 
const privateKey = generatePrivateKey();
const account = privateKeyToAccount(`${privateKey}`);

Set up Nexus client with paymaster

Login to the Dashboard and setup a v2 paymaster. Let's configure a client for the Smart Account with a paymasterUrl to enable gasless transactions. A bundlerUrl is required to submit transactions to the Network, which will initialize the Smart Account.

import { createSmartAccountClient, createBicoPaymasterClient } from "@biconomy/sdk";
import { baseSepolia } from "viem/chains"; 
import { http, parseEther } from "viem";
import { privateKeyToAccount, generatePrivateKey } from "viem/accounts";
 
const privateKey = generatePrivateKey();
const account = privateKeyToAccount(`${privateKey}`);
 
const bundlerUrl = "https://bundler.biconomy.io/api/v3/84532/nJPK7B3ru.dd7f7861-190d-41bd-af80-6877f74b8f44";
const paymasterUrl = "https://paymaster.biconomy.io/api/v2/84532/F7wyL1clz.75a64804-3e97-41fa-ba1e-33e98c2cc703"; 
 
const nexusClient = await createSmartAccountClient({
    signer: account,
    chain: baseSepolia,
    transport: http(),
    bundlerTransport: http(bundlerUrl),
    paymaster: createBicoPaymasterClient({paymasterUrl})
});

Send gasless transaction

Next, define the transaction you want to send. Use the sendTransaction method to send the transaction. Since we have a paymaster configured, this transaction will be gasless.

 
import { createSmartAccountClient, createBicoPaymasterClient } from "@biconomy/sdk";
import { baseSepolia } from "viem/chains"; 
import { http, parseEther } from "viem";
import { privateKeyToAccount, generatePrivateKey } from "viem/accounts";
 
const privateKey = generatePrivateKey();
const account = privateKeyToAccount(`${privateKey}`);
 
const bundlerUrl = "https://bundler.biconomy.io/api/v3/84532/nJPK7B3ru.dd7f7861-190d-41bd-af80-6877f74b8f44";
const paymasterUrl = "https://paymaster.biconomy.io/api/v2/84532/F7wyL1clz.75a64804-3e97-41fa-ba1e-33e98c2cc703";
 
const nexusClient = await createSmartAccountClient({
    signer: account,
    chain: baseSepolia,
    transport: http(),
    bundlerTransport: http(bundlerUrl),
    paymaster: createBicoPaymasterClient({paymasterUrl})
}); 
 
const hash = await nexusClient.sendTransaction({ calls:  
    [{to : '0xf5715961C550FC497832063a98eA34673ad7C816', value: parseEther('0')}] },
); 
console.log("Transaction hash: ", hash) 
const receipt = await nexusClient.waitForTransactionReceipt({ hash });

By following these steps, you have successfully sent a gasless transaction using the SDK. For more advanced features and options, refer to the official documentation.

See sendTransaction Docs