Creating a WhatsApp AI Assistant Using n8n: A Step-by-Step Guide

April 2025 · Your Name or Blog Name

Build your own AI-powered WhatsApp chatbot using n8n, WhatsApp Business Cloud API, and OpenAI. This guide walks you through every step—from setup to testing—with real-world error handling and solutions.

Table of Contents

1. Introduction
2. Prerequisites
3. Registering Your WhatsApp Business App
4. Configuring Your Webhook in n8n
5. Processing Incoming Messages
6. Integrating OpenAI for Responses
7. Sending Replies via WhatsApp
8. Common Errors & Fixes
9. Going Live
10. Conclusion & Next Steps

1. Introduction

Want to chat with an AI on WhatsApp? In this tutorial, you’ll learn how to build a WhatsApp AI Assistant using:

• n8n (automation tool)
• WhatsApp Business Cloud API
• OpenAI (for generating intelligent replies)

By the end, you’ll have a working chatbot and gain hands-on experience with APIs, webhooks, and automation.

2. Prerequisites

• n8n account (Cloud or self-hosted)
• Meta Developer account with WhatsApp Business Cloud API access
• OpenAI API key
• Basic understanding of APIs and webhook workflows

3. Registering Your WhatsApp Business App

A. Create WhatsApp App in Meta Developer

1. Visit Meta for Developers
2. Create a new app: choose Business → WhatsApp
3. Link or create a WhatsApp Business Account

B. Obtain Testing Credentials

Your app dashboard will show:

• Test phone number
• Phone Number ID
• Temporary access token (valid for only 24 hours)

Tip: For long-term use, generate a 60-day system-user token later.

C. Add Recipients to Test List

By default, only approved numbers can receive messages:

1. Navigate to WhatsApp → API Setup
2. Add numbers in E.164 format (e.g., +923001234567)
3. Users must accept the invite via WhatsApp to become valid recipients

4. Configuring Your Webhook in n8n

A. Create a Webhook Node

• Method: GET (for initial verification)
• Endpoint example:

  https://yourname.app.n8n.cloud/webhook/your-unique-id/webhook
  

B. Verify the Webhook with Meta

In your app’s Webhook section:

• Callback URL: your n8n webhook URL
• Verify Token: any secret string you choose (e.g., mySecret2025)

C. Echo Back Meta’s Challenge

Configure n8n’s Webhook node response:

This ensures Meta can verify your endpoint successfully.

5. Processing Incoming Messages

WhatsApp sends JSON data with structure like:

{
  "entry": [
    {
      "changes": [
        {
          "value": {
            "messages": [
              {
                "from": "923001234567",
                "text": { "body": "Hello bot!" }
              }
            ],
            "metadata": {
              "phone_number_id": "698352170035199"
            }
          }
        }
      ]
    }
  ]
}

Extract:

• from: user’s number
• text.body: user’s text
• metadata.phone_number_id: correct sender ID

6. Integrating OpenAI for Responses

Use an HTTP Request node to call OpenAI:

POST https://api.openai.com/v1/chat/completions
Authorization: Bearer YOUR_OPENAI_API_KEY
Content-Type: application/json

{
  "model": "gpt-4o-mini",
  "messages": [
    { "role": "system", "content": "You are a helpful WhatsApp AI assistant." },
    { "role": "user", "content": "{{ $json[...] }}" }
  ]
}

Replace {{ $json[...] }} with the actual path to the user’s message text from the Webhook node.

7. Sending Replies via WhatsApp

Use another HTTP Request node to respond:

POST https://graph.facebook.com/v21.0/{{ $json[...] }}/messages
Authorization: Bearer YOUR_LONG_LIVED_TOKEN
Content-Type: application/json

{
  "messaging_product": "whatsapp",
  "to": "{{ $json[...] }}",
  "text": {
    "body": "{{ $node['OpenAI Response'].json.choices[0].message.content }}"
  }
}

Use the metadata’s phone_number_id for the endpoint and from for the recipient. This avoids hardcoding and ensures proper routing.

8. Common Errors & Fixes

• Recipient phone number not in allowed list
  → Add as test number or switch to Live mode

• 401 – Session expired
  → Refresh token via Graph API:

  GET https://graph.facebook.com/v21.0/oauth/access_token
  ?grant_type=fb_exchange_token
  &client_id=YOUR_APP_ID
  &client_secret=YOUR_APP_SECRET
  &fb_exchange_token=YOUR_CURRENT_TOKEN
  

• Webhook verification failed
  → Ensure verify token matches between Meta and n8n and echo hub.challenge

• No execution data available
  → Trigger workflow via actual WhatsApp message, not manual run

9. Going Live

1. Add a Privacy Policy URL in Meta App → Settings → Basic (required for live access)
2. Switch app to Live mode once all compliance items are met
3. Remove restricted recipient list
4. Use WhatsApp message templates for messages sent after 24 hours of user interaction

10. Conclusion & Next Steps

Congrats! You now have a WhatsApp AI Assistant built with n8n and OpenAI.

Where to go from here:

• Wire up custom knowledge (PDFs, documents)
• Implement memory for conversation context
• Launch multilingual support
• Export n8n workflow as JSON for reuse

Need help? Join the n8n Community Forum or OpenAI Discord to connect with fellow builders.

Happy automating!