To implement Firebase reCAPTCHA v3 verification in a Next.js project, you'll need to use the Firebase Admin SDK on the server-side to verify the reCAPTCHA token sent from the client. Here's a step-by-step guide to achieve this:

  1. Set up Firebase in your Next.js project:

    Follow the Firebase documentation to set up Firebase for your Next.js project. You'll need to install the necessary Firebase packages, initialize Firebase, and configure it with your Firebase project credentials.

  2. Add the Firebase Admin SDK:

    Install the Firebase Admin SDK package, which allows you to use Firebase services on the server-side.

    npm install firebase-admin

    Initialize the Admin SDK in your Next.js server file (e.g., pages/api/firebase.js):

    import admin from 'firebase-admin'; if (!admin.apps.length) { admin.initializeApp({ credential: admin.credential.applicationDefault(), // or provide your own credentials }); } export default admin;
  3. Create an API route to verify the reCAPTCHA token:

    In your Next.js project, create an API route (e.g., pages/api/verify-recaptcha.js) to handle the reCAPTCHA verification. This API route will use the Firebase Admin SDK to verify the token.

    import admin from './firebase'; export default async function handler(req, res) { if (req.method !== 'POST') { return res.status(405).end(); // Method Not Allowed } const { token } = req.body; try { // Verify the reCAPTCHA token using the Firebase Admin SDK const { score, action } = await admin.auth().verifyIdToken(token); // You can now use the score and action for further validation // For example, check if score >= 0.5 to determine if it's not a bot return res.status(200).json({ score, action }); } catch (error) { console.error('Error verifying reCAPTCHA token:', error); return res.status(500).json({ error: 'Verification failed.' }); } }
  4. Add the client-side code to call the API route:

    In your Next.js client-side code, use fetch or a library like axios to send the reCAPTCHA token to the API route you created.

    import { useState } from 'react'; import axios from 'axios'; const MyComponent = () => { const [token, setToken] = useState(''); const handleVerify = async () => { try { const response = await'/api/verify-recaptcha', { token }); console.log('Verification response:',; } catch (error) { console.error('Verification error:', error); } }; return ( <div> <input type="text" value={token} onChange={(e) => setToken(} /> <button onClick={handleVerify}>Verify reCAPTCHA</button> </div> ); }; export default MyComponent;

    In this example, you would replace the <input> element with the actual reCAPTCHA widget. When the user interacts with the reCAPTCHA widget, you'll obtain the reCAPTCHA token, which you can then send to the API route using (or fetch) for verification.

Please note that reCAPTCHA v3 does not display a traditional "I am not a robot" checkbox. It runs in the background and assigns a score to the interaction, which you can use to determine if the interaction is likely from a human or a bot. Make sure to handle the score accordingly in your verification logic.

With the steps above, you should be able to verify the reCAPTCHA token on the server-side using Firebase Admin SDK in your Next.js project.

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