---
title: "Webhook"
description: "A webhook is an automatic HTTP notification one service sends to another when an event occurs. See how it differs from a traditional API."
url: "https://nodea.io/en/glossary/webhook"
lang: "en"
updated: "2026-07-13"
---

# Webhook

> A webhook is a mechanism in which one service automatically sends an HTTP request to a specified URL of another application when a defined event occurs.

A **webhook** is a way of integrating two systems in which one service automatically sends an [HTTP](https://nodea.io/en/glossary/https) request to a previously agreed URL of another application exactly when a defined event occurs — for example an order being paid, a form submitted or a deployment finished. Instead of repeatedly asking the server whether anything has changed, the receiving application simply waits for a notification.

## How a webhook works

The receiver exposes a public URL (an endpoint) and the sender is configured with it in the service's settings. When an event occurs, the sender delivers a request to that URL — usually a POST carrying a JSON payload describing what happened. The receiver verifies the request's authenticity, for instance by checking a signature, processes the data and returns a confirmation code. All communication takes place over HTTPS so the payload cannot be intercepted or tampered with.

## Webhook versus API

A webhook complements a traditional [API](https://nodea.io/en/glossary/api): an API responds to a client's request, while a webhook is driven by an event on the server side. It is a "don't call us, we'll call you" model that reduces unnecessary traffic and delivers an immediate reaction. Webhooks are the basis of many automations — they notify payment systems, trigger [CI/CD](https://nodea.io/en/glossary/ci-cd) pipelines on every code push, integrate stores with shipping systems and fire off [autoresponders](https://nodea.io/en/glossary/autoresponder). When designing a webhook receiver it is worth ensuring idempotency, handling retries and verifying signatures, so that duplicated or forged events do not cause problems. Used well, webhooks turn scattered systems into a coordinated whole that reacts to events in real time.

### How does a webhook differ from an API?

With a traditional API your application asks the server for data. A webhook reverses the direction — the server notifies your application when something happens, so you do not have to keep polling to check for changes.

## Related

- [API](https://nodea.io/en/glossary/api)
- [HTTPS](https://nodea.io/en/glossary/https)
- [Autoresponder](https://nodea.io/en/glossary/autoresponder)
- [CI/CD](https://nodea.io/en/glossary/ci-cd)

---

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