After web1 and web2, Web3 development is now transforming how users interact with applications by leveraging blockchain technology for authentication and identity management. Integrating Web3 authentication into a Next.js application allows users to log in securely without traditional passwords, relying instead on their crypto wallets, such as MetaMask. This guide walks through the process of integrating Web3 authentication step by step.

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Prerequisites

1. Familiarity with Next.js and React.
2. A basic understanding of Ethereum wallets like MetaMask.
3. Node.js installed (preferably v20 or later).

4. An active Ethereum wallet for testing.

    

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Integrating Web3 Authentication into a Next.js Application

Setting Up a Next.js Application

Begin by creating a new Next.js project:

npx create-next-app@latest web3-auth-nextjs
cd web3-auth-nextjs
npm install ethers

Here, we use the ethers library to interact with Ethereum wallets.

Step 1: Adding Wallet Connection Logic

Create a utility for connecting to a wallet. In your utils folder, add a file named web3.js:

// utils/web3.js
import { ethers } from 'ethers';

export const connectWallet = async () => {
 try {
   if (!window.ethereum) {
     throw new Error('MetaMask is not installed');
   }

   const provider = new ethers.BrowserProvider(window.ethereum);
   await window.ethereum.request({ method: 'eth_requestAccounts' });
   const accounts = await provider.listAccounts();
   const signer = await provider.getSigner();

   if (accounts.length === 0) {
     throw new Error('No accounts found. Please connect a wallet.');
   }

   return { provider, signer, account: accounts[0] };
 } catch (error) {
   console.error('Error connecting wallet:', error.message);
   throw error;
 }
};

export const signMessage = async (signer, message) => {
 try {
   const signature = await signer.signMessage(message);
   return signature;
 } catch (error) {
   console.error('Error signing message:', error.message);
   throw error;
 }
};

Step 2: Creating a Web3 Context with Zustand

To manage Web3 states like connection status and account information, use Zustand:

npm install zustand

Then create a context in store/web3Store.js:

// store/web3Store.js
import { create } from 'zustand';

export const useWeb3Store = create((set) => ({
 account: null,
 setAccount: (account) => set({ account }),
}));

Step 3: Building the Login Component

In components/WalletLogin.js, add the following:

'use client';

import { connectWallet, signMessage } from '../utils/web3';
import { useWeb3Store } from '../store/web3Store';
import { useState } from 'react';

const WalletLogin = () => {
 const [error, setError] = useState('');
 const { account, setAccount } = useWeb3Store();

 const handleLogin = async () => {
   try {
     const { signer, account } = await connectWallet();
     const message = 'Authenticate with Web3';
     const signature = await signMessage(signer, message);

     console.log('Signature:', signature); // For backend validation
     setAccount(account?.address);
   } catch (err) {
     setError(err.message);
   }
 };

 return (
   

     {account ? (
       
Connected as: {account}
     ) : (
       
         Connect Wallet
       
     )}
     {error && {error}
}
   
 );
};

export default WalletLogin;

Step 4: Adding Authentication to Pages

To use the WalletLogin component, update your pages/index.js:

import WalletLogin from '../components/walletLogin';

export default function Home() {
 return (
   
     

       Web3 Authentication in Next.js