What Is a Webhook? Plain-English Definition

Description

Glossary What is a webhook?

A webhook is an automatic message that one system sends to a URL on another system the moment an event happens, such as a payment succeeding or an order shipping. Your software does not have to keep asking whether anything has changed; it is told.

Discuss an integration Last updated 2 October 2026

A plain example

A customer pays on your website through a payment gateway. Two things could tell your system the payment went through:

Without a webhook, your system asks the gateway every few seconds, "has order 1042 been paid yet?" Most of those questions get the answer "no". If the customer closes the browser before the answer is "yes", your system may never find out.

With a webhook, the gateway sends your system one message the moment the payment succeeds. Your system marks the order as paid and sends the confirmation, whether or not the customer is still on the page.

The message is an ordinary web request carrying a small block of data. An illustration of the shape, not any provider's exact format:

"event": "payment.captured",

"created_at": "2026-10-02T09:14:07Z",

"data": {

"order_id": "order_1042",

"amount": 149900,

"currency": "INR",

"status": "captured"

The receiving system reads event to learn what happened and data to learn the details, then replies "received".

Why it matters when you commission software

Webhooks are where integrations most often go wrong, because the failures are silent. When a quote includes "payment gateway integration" or "WhatsApp integration", four things separate a reliable build from a fragile one:

Question to ask

Why

Is every incoming message verified?

Without a signature check, anyone who finds the URL can tell your system an order was paid.

What happens when the same message arrives twice?

Providers resend. The second copy must not create a second order or a second refund.

What happens when a message never arrives?

Servers go down. A scheduled check against the provider's API catches what was missed.

Are messages logged?

When a customer says "I paid", the log is how you find out what happened.

These are part of what WavX builds into payment and messaging integrations; see API and system integration services.

Related terms

API : the interface your system uses to ask another system for something. A webhook is the reverse direction.

Event: the thing that happened and triggered the webhook, such as payment.captured or order.shipped .

Endpoint: the URL on your system that receives the message.

Retry: a provider's repeat attempt to deliver a message your system did not acknowledge.

Frequently asked questions

What is the difference between a webhook and an API?

With an API, your system asks another system a question and gets an answer. With a webhook, the other system tells yours when something happens, without being asked. Most integrations use both: the API to send instructions and fetch details, webhooks to hear about events.

What happens if my server is down when a webhook is sent?

The message fails. Most providers retry several times over a period they document, then stop. A sound integration therefore also checks the provider's API on a schedule to catch anything that was missed.

Are webhooks secure?

They are as secure as the receiving end makes them. The receiver must verify that each message really came from the provider, normally by checking a signature the provider attaches, and must treat the same message arriving twice as normal.

Related

What is an API?

Razorpay integration

WhatsApp Business API integration

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