How to build a public NeverBounce integration: Building the Auth Flow

Hey there, fellow JavaScript enthusiasts! Ready to dive into the world of NeverBounce integrations? Today, we're going to walk through building a rock-solid authorization flow for your user-facing integration. Let's get started!

Introduction

NeverBounce is a fantastic email verification service, and its API is a powerhouse for keeping your email lists clean. But before we can tap into that power, we need to set up a secure authorization flow. Trust me, it's not as daunting as it sounds!

Prerequisites

Before we jump in, make sure you've got:

• A NeverBounce API key (if you don't have one, go grab it!)
• Node.js and Express.js set up on your machine
• A basic understanding of OAuth 2.0 (don't worry if you're rusty, we'll cover the essentials)

Setting up the project

First things first, let's get our project off the ground:

mkdir neverbounce-integration
cd neverbounce-integration
npm init -y
npm install express axios dotenv

Great! Now we've got the basics in place.

Implementing the authorization flow

This is where the magic happens. We'll create a few key endpoints to handle the OAuth dance:

const express = require('express');
const axios = require('axios');
require('dotenv').config();

const app = express();

app.get('/auth', (req, res) => {
  // Redirect to NeverBounce authorization page
});

app.get('/callback', async (req, res) => {
  // Handle the OAuth callback
  // Exchange authorization code for access token
});

// Store and manage access tokens (we'll use in-memory for simplicity)
let accessToken = null;

Securing the integration

Security is crucial, so let's implement PKCE and use a state parameter:

const crypto = require('crypto');

function generateCodeVerifier() {
  return crypto.randomBytes(32).toString('hex');
}

function generateCodeChallenge(verifier) {
  return crypto.createHash('sha256').update(verifier).digest('base64')
    .replace(/\+/g, '-')
    .replace(/\//g, '_')
    .replace(/=/g, '');
}

app.get('/auth', (req, res) => {
  const codeVerifier = generateCodeVerifier();
  const codeChallenge = generateCodeChallenge(codeVerifier);
  const state = crypto.randomBytes(16).toString('hex');
  
  // Store codeVerifier and state for later use
  
  // Redirect to NeverBounce authorization page with codeChallenge and state
});

Making authenticated API calls

Now that we've got our access token, let's put it to use:

async function makeNeverBounceRequest(endpoint, method = 'GET', data = null) {
  try {
    const response = await axios({
      method,
      url: `https://api.neverbounce.com/v4/${endpoint}`,
      headers: {
        'Authorization': `Bearer ${accessToken}`,
        'Content-Type': 'application/json'
      },
      data
    });
    return response.data;
  } catch (error) {
    // Handle errors, including token expiration
  }
}

Error handling and edge cases

Always be prepared for things to go sideways:

app.get('/callback', async (req, res) => {
  try {
    // Exchange code for token
  } catch (error) {
    console.error('Authorization error:', error);
    res.status(500).send('Authorization failed');
  }
});

// Implement token revocation
app.post('/revoke', async (req, res) => {
  // Revoke the token with NeverBounce
  accessToken = null;
  res.send('Token revoked');
});

Testing the integration

Don't forget to test your work! Set up a test environment and write some unit tests:

const chai = require('chai');
const chaiHttp = require('chai-http');
chai.use(chaiHttp);
const expect = chai.expect;

describe('Authorization Flow', () => {
  it('should redirect to NeverBounce auth page', (done) => {
    chai.request(app)
      .get('/auth')
      .end((err, res) => {
        expect(res).to.redirectTo(/neverbounce\.com/);
        done();
      });
  });
  
  // Add more tests for callback, token exchange, etc.
});

Best practices and optimization

To take your integration to the next level:

1. Implement token caching to reduce API calls
2. Use secure storage (like Redis) for sensitive data in production
3. Implement proper logging for easier debugging

Conclusion

And there you have it! You've just built a secure, efficient authorization flow for your NeverBounce integration. Remember, this is just the beginning. As you expand your integration, keep security at the forefront and always stay up to date with NeverBounce's latest API changes.

Now go forth and verify those emails with confidence! Happy coding! 🚀