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Setting up a Paymaster for Smart Account Transactions

A Paymaster is a component that can sponsor gas fees for users, enabling gasless transactions in your dApp. This guide will show you how to set up and integrate the JiffyPaymaster in your application.

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Prerequisites

Before setting up the Paymaster, ensure you have:
  1. A Next.js project with Auth Provider Setup
  2. The necessary dependencies installed: 
    npm install @jiffy-labs/web3a

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Configuration

First, let’s import the necessary modules and set up our configuration: 
import { JiffyPaymaster } from "@jiffy-labs/web3a";

const jiffyscanKey = process.env.NEXT_PUBLIC_JIFFYSCAN_API_KEY as string;
const bundlerUrl = process.env.NEXT_PUBLIC_BUNDLER_URL as string;

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Creating the JiffyPaymaster Instance

Now, let’s create an instance of the JiffyPaymaster: 
const jiffyPaymaster = new JiffyPaymaster(bundlerUrl, selectedChain.chain.id, {
    "x-api-key": jiffyscanKey,
});

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Integrating the Paymaster with Smart Account Client

To use the Paymaster in your Smart Account transactions, integrate it into your Smart Account client configuration: 
const smartAccountClient = createSmartAccountClient({
    account: simpleSmartAccountClient,
    entryPoint: ENTRYPOINT_ADDRESS_V06,
    chain: selectedChain.chain,
    bundlerTransport: bundlerTransport,
    middleware: {
        gasPrice: async () => (await bundlerClient.getUserOperationGasPrice()).fast,
        sponsorUserOperation: jiffyPaymaster.sponsorUserOperationV6,
    },
});
By adding the sponsorUserOperation middleware and setting it to jiffyPaymaster.sponsorUserOperationV6, you’re configuring your Smart Account client to use the JiffyPaymaster for sponsoring gas fees.