Webhooks

Definition

Webhooks are automated messages sent from one application to another when a specific event occurs. They use HTTP callbacks to deliver real-time data to a designated URL without requiring the receiving system to constantly check for updates.

For example, a payment processor can send a webhook to an e-commerce platform when a transaction is completed. This immediate event-driven communication makes processes faster and more efficient compared to traditional polling methods.

Advanced

At an advanced level, webhooks are designed as lightweight event notification systems. They typically include a payload in JSON or XML format containing details of the event. Authentication and validation techniques, such as HMAC signatures or secret tokens, are used to confirm the authenticity of incoming requests.

Scalability considerations include retry mechanisms, error handling, and queueing to ensure delivery even during system downtime. Webhooks are commonly integrated with APIs, CI/CD pipelines, and third-party services for real-time automation.

Why it matters

• Enables real-time communication between systems.
• Reduces the need for resource-heavy polling.
• Automates workflows across multiple platforms.
• Improves efficiency in event-driven architectures.

Use cases

• Notifying an app when a new payment is processed.
• Sending updates to chat tools when code is deployed.
• Triggering CRM updates when a lead submits a form.
• Automating alerts for system monitoring and security events.

Metrics

• Delivery success and failure rates.
• Latency between event occurrence and webhook delivery.
• Number of retries for failed webhook calls.
• System uptime and availability for receiving endpoints.

Issues

• Failed deliveries if receiving endpoints are down or misconfigured.
• Security risks if webhooks are not validated or secured.
• Lack of standardisation across providers complicates integration.
• Excessive retries or loops may overload systems.

Example

An online store uses webhooks from its payment gateway. When a customer completes a purchase, the gateway sends a webhook with transaction details to the store’s backend. This triggers automatic order fulfilment and sends a confirmation email to the customer in real time.