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

Hey there, fellow JavaScript enthusiast! Ready to dive into the world of ConvertKit integrations? Today, we're going to tackle the most crucial part of building a public integration: the authorization flow. Buckle up, because we're about to make your integration secure and user-friendly in no time!

Introduction

ConvertKit's API is a powerful tool for creators, and building a public integration can open up a world of possibilities. But before we can start playing with subscriber data and automations, we need to nail the authorization process. It's the gatekeeper that ensures only the right people access the right data. Let's get this right, shall we?

Prerequisites

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

• A ConvertKit Developer Account (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, we'll refresh your memory)

Got all that? Great! Let's build something awesome.

Setting up the project

First things first, head over to your ConvertKit Developer Account and create a new application. You'll get a client ID and client secret – treat these like your secret sauce. Keep them safe; we'll need them soon.

Implementing the Authorization Flow

Step 1: Redirect to ConvertKit's authorization page

Let's kick things off by sending your users to ConvertKit's authorization page. Here's how:

const authUrl = `https://app.convertkit.com/oauth/authorize?client_id=${YOUR_CLIENT_ID}&redirect_uri=${YOUR_REDIRECT_URI}&response_type=code&scope=read_subscribers`;

// Use this URL when you want to start the auth process

Pro tip: On the client-side, you can use window.location.href = authUrl to redirect the user.

Step 2: Handling the callback

Once the user grants permission, ConvertKit will redirect them back to your specified callback URL with an authorization code. Let's catch that:

app.get('/callback', (req, res) => {
  const authCode = req.query.code;
  // Now, let's exchange this code for an access token
});

Step 3: Exchanging the code for an access token

Time to trade that code for the real prize – an access token:

const axios = require('axios');

const getAccessToken = async (authCode) => {
  const response = await axios.post('https://api.convertkit.com/v3/oauth/token', {
    client_id: YOUR_CLIENT_ID,
    client_secret: YOUR_CLIENT_SECRET,
    code: authCode,
    grant_type: 'authorization_code',
    redirect_uri: YOUR_REDIRECT_URI
  });

  return response.data.access_token;
};

Remember to store this token securely. It's your golden ticket to the ConvertKit API!

Refreshing the access token

Access tokens don't last forever. Let's implement a refresh mechanism:

const refreshToken = async (refreshToken) => {
  const response = await axios.post('https://api.convertkit.com/v3/oauth/token', {
    grant_type: 'refresh_token',
    refresh_token: refreshToken,
    client_id: YOUR_CLIENT_ID,
    client_secret: YOUR_CLIENT_SECRET
  });

  return response.data;
};

Making authenticated requests

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

const getSubscribers = async (accessToken) => {
  try {
    const response = await axios.get('https://api.convertkit.com/v3/subscribers', {
      headers: { Authorization: `Bearer ${accessToken}` }
    });
    return response.data;
  } catch (error) {
    // Handle unauthorized errors here
    if (error.response && error.response.status === 401) {
      // Time to refresh that token!
    }
  }
};

Best practices and security considerations

• Store tokens securely (please, not in plain text!)
• Implement PKCE for added security (your future self will thank you)
• Set up rate limiting to play nice with ConvertKit's API
• Handle errors gracefully – your users will appreciate it

Testing the integration

Before you pop the champagne, let's make sure everything works:

1. Try the auth flow yourself (manual testing is underrated)
2. Write some automated tests (your code deserves it)

// A simple test example
test('should exchange auth code for access token', async () => {
  const authCode = 'test_auth_code';
  const accessToken = await getAccessToken(authCode);
  expect(accessToken).toBeDefined();
});

Conclusion

And there you have it! You've just built a rock-solid authorization flow for your ConvertKit integration. Pat yourself on the back – you've tackled one of the trickiest parts of API integration.

What's next? Start building out those awesome features you've been dreaming of. The ConvertKit API is your oyster, and you've got the keys to the kingdom.

Remember, the best integrations are built with creativity and a dash of perseverance. So go forth and create something amazing. Your users are waiting!

Happy coding, and may your integration be forever bug-free! 🚀✨