Webhook

A webhook is a way for one application to automatically send data to another application in real time when a specific event occurs. Unlike a regular API call (where you ask for information), a webhook pushes information to you as soon as something happens.

The doorbell analogy

Think about the difference between checking your front door every five minutes to see if someone's there (polling an API) versus having a doorbell that rings when someone arrives (a webhook). The doorbell is far more efficient — it only triggers when something actually happens.

How webhooks work

1. You register a URL: You give an application a web address (URL) on your server where it should send notifications.
2. An event occurs: Something happens in the source application — a customer makes a payment, a form is submitted, a file is uploaded.
3. Data is sent: The source application immediately sends the event data to your URL as an HTTP request.
4. Your system processes it: Your application receives the data and takes action — updates a database, sends an email, triggers a workflow.

Common webhook use cases

• Payment notifications: Stripe sends a webhook when a customer completes a payment, so you can activate their account instantly.
• Form submissions: A webhook fires when someone fills out a contact form, sending the data to your CRM.
• Repository updates: GitHub sends a webhook when code is pushed, triggering your CI/CD pipeline to run tests.
• Inventory updates: An e-commerce platform sends a webhook when stock levels change, so your website reflects real-time availability.
• Communication triggers: A webhook from your calendar app triggers a reminder message in Slack.

Webhooks in automation tools

If you use automation platforms like Zapier, Make, or n8n, webhooks are often the starting point of a workflow. They allow you to trigger automations based on events from almost any application that supports webhooks — which is most modern software.

Key considerations

• Security: Always verify that incoming webhooks are actually from the expected source (most services provide signature verification).
• Reliability: Webhooks can fail if your server is down. Good webhook implementations include retry logic.
• Idempotency: Your system should handle receiving the same webhook twice gracefully (it happens occasionally).