What Are Webhooks? A Comprehensive Guide for Developers

Webhooks offer a modern, efficient alternative to API polling for real-time data. Unlike polling where an application repeatedly requests updates, webhooks enable servers to push data to applications automatically when specific events occur, earning them the name "reverse APIs." A webhook setup involves a provider that sends notifications, a defined event that triggers the notification, a webhook URL or endpoint in your application to receive data, and a payload containing event details, typically in JSON format. This push model is significantly more efficient and provides true real-time data compared to polling's resource-intensive, near real-time approach. While polling relies on a request-response model, webhooks are event-driven, initiating communication from the server. To enable webhooks for local development, tools like Tunnelmole create public URLs for local servers, bridging the gap between the internet and localhost. Common use cases include CI/CD automation, e-commerce workflows, payment notifications, CMS integrations, IoT device communication, and social media monitoring. Building a webhook listener with Node.js and Express involves setting up a server to receive POST requests at a designated endpoint. Middleware like body-parser is used to parse incoming JSON payloads. It's crucial for the server to respond with a 200 OK status to confirm successful receipt, preventing duplicate deliveries. Tunnelmole is then used to expose this local server to the internet via a public URL, allowing external services to send webhook requests to it for testing and development.