Set up an API endpoint using Express.js and utilize the Infobip SDK's `channels.whatsapp.send()` method with a payload containing the recipient's number, your sender number (from Infobip), and the message content. Validate inputs and handle the API response appropriately within your controller logic.

The Infobip WhatsApp API, accessible through their Node.js SDK, allows developers to send and receive WhatsApp messages programmatically. It handles the connection to the WhatsApp Business Platform, simplifying integration with your Node.js applications.

Infobip uses a webhook to deliver incoming WhatsApp messages to your application. This webhook acts as a public URL where Infobip sends real-time HTTP POST requests containing message data when a user interacts with your WhatsApp Sender.

Webhook signature verification is crucial for production environments. Always verify the signature in your webhook handler to ensure the incoming request is authentic and hasn't been tampered with, confirming its origin from Infobip.

Yes, you can test WhatsApp integration locally with tools like ngrok, which creates a temporary public URL that tunnels requests to your local development server, allowing you to receive webhooks from Infobip for testing.

Create a dedicated webhook endpoint (e.g., `/infobip-webhook`) in your Express.js application to handle incoming POST requests from Infobip. Configure this endpoint's public URL in the Infobip portal. The request body will contain the WhatsApp message data.

The Infobip WhatsApp Sender number is the registered and approved phone number associated with your WhatsApp Business account. Obtain this number from the "Channels and Numbers > WhatsApp" section of your Infobip portal, used for sending messages.

Implement robust error handling using `try...catch` blocks around Infobip API calls. Handle both API errors (using error codes and messages from the SDK) and potential network issues. Structured logging and retry mechanisms are recommended.

Key security practices include securing your API key using environment variables, verifying webhook signatures to prevent spoofing, validating and sanitizing all user inputs, and implementing rate limiting to protect against abuse.

Install the Infobip Node.js SDK (`@infobip-api/sdk`) and create an Infobip client instance using your API key and base URL. Centralize this setup in a service module for better organization.

ngrok is essential during development as it provides a public, secure URL for your local server, enabling Infobip to deliver webhooks to your application even when running locally.

Use nodemon during development to automatically restart your server when you make code changes, streamlining the development workflow.

Get your public application URL and combine it with your webhook route path. Configure this full URL in the "Webhook" or "API Integrations" section for your WhatsApp Sender within the Infobip portal.

The article specifically mentions and provides guidance on using Express.js, a popular and well-suited framework for creating the API and webhook handling required for the WhatsApp integration.