What is a Webhook? Definition, Examples & How It Works

If you’ve ever watched a Slack message pop up the instant someone pushes code, or received a Stripe receipt the second a payment clears, you’ve already experienced a webhook in action. These automated callbacks are the quiet backbone of modern real-time integration, pushing data between apps without anyone hitting refresh. By the end of this guide, you’ll understand exactly what a webhook is, how it works, and when it beats a traditional API.

Primary protocol: HTTP POST · Event-driven: Yes · Common use cases: CI/CD, chat notifications, payment confirmations · Alternative to polling: Yes

Four attributes define every webhook: protocol, direction, trigger, and payload format. Here’s how they stack up in practice.

What is a webhook?

How does a webhook work?

• A webhook is an automated HTTP callback that sends data from one app to another when a specific event occurs (Red Hat (enterprise automation leader)).
• The event source sends the request to a unique URL provided by the receiving application (Zapier (integration platform)).
• This contrasts with polling, where the consumer repeatedly checks for updates (Unito (workflow integration tool)).

When an event occurs (e.g., a new commit in GitHub), the source application sends an HTTP POST request with a payload — typically in JSON — to the webhook URL configured by the receiving system. The receiving endpoint then processes that data and triggers whatever action it was built for, like sending a Slack notification or updating a database.

The pattern: Webhooks invert the traditional request-response model. Instead of asking for data, you let the data come to you. This shift from pull to push is what makes webhooks so efficient for real-time updates.

What are webhooks used for?

Common use cases: CI/CD, messaging, payments

• CI/CD pipelines: GitHub triggers a webhook on every push to automatically build and deploy code (GitHub (code hosting platform)).
• Chat notifications: Discord and Slack use webhooks to post messages from external services directly into channels (Discord Support (platform documentation)).
• Payment confirmations: Stripe sends a webhook event when a charge succeeds, updating order status in real time (Merge.dev (customer data platform)).
• Automated workflows: Creating an invoice when a deal is closed, or generating a ticket in engineering when a lead is created (Merge.dev (customer data platform)).

These examples share a common thread: a change in one system instantly triggers a meaningful action in another, with zero manual intervention. Webhooks replace the need for constant polling or manual data syncs.

Why this matters: For any business that depends on timely data across multiple tools — sales, support, engineering — webhooks are the cheapest way to close the loop. They reduce latency from minutes (or hours) to milliseconds.

What is webhook vs API?

What is the main difference?

• API (request-response): The consumer sends a request and waits for a response. It controls when data is fetched (TechTarget (enterprise IT guidance)).
• Webhook (push-based): The source sends data automatically when an event occurs, without being asked (Unito (workflow integration tool)).
• Polling overhead: APIs often require repeated requests to check for new data, wasting bandwidth and compute resources that webhooks eliminate (Red Hat (enterprise automation leader)).

When to use webhook vs API?

• Use webhooks when you need real-time notifications, data is event-driven, and you control the receiving endpoint.
• Use APIs when you need on-demand data, two-way communication, or you need to query historical records.
• Combine both for maximum flexibility: webhooks for instant events, APIs for subsequent data retrieval (Zapier (integration platform)).

Three dimensions, one clear distinction: webhooks push, APIs pull.

The implication: Choosing between webhooks and APIs isn’t a binary — most modern applications use both. Webhooks handle the “when something happens” part, while APIs handle the “show me the current state” part.

What is an example of a webhook?

Example using Discord webhook

• In Discord server settings, go to Integrations > Webhooks and create a new webhook (Discord Support (platform documentation)).
• You get a unique URL that accepts HTTP POST requests with a JSON payload.
• Anytime an external service sends a POST to that URL with a message, Discord posts it in the selected channel.

Example using GitHub webhook

• In a GitHub repository, go to Settings > Webhooks and add a new webhook pointing to your server’s endpoint (GitHub (code hosting platform)).
• Choose events like “push” or “pull_request” and a JSON payload is sent to your URL every time that event occurs.
• Your server can then trigger a deployment, run tests, or notify a chat room.

What this means: These examples show that webhooks turn any event into an immediate, automated action. The setup is minimal — a URL and a payload — but the automation payoff is enormous.

How do we create a webhook?

Steps to create a webhook receiver

1. Set up a receiving endpoint — a URL that accepts HTTP POST requests. You can use a simple server written in Node.js, Python, or any language, or a service like Webhook.site (webhook testing tool) for testing.
2. Register the webhook with the provider — in GitHub, Discord, Stripe, Zapier, etc., enter the receiver URL and choose which events to trigger it.
3. Define the payload format — typically JSON, containing the event data. The provider’s documentation specifies the structure.
4. Handle the incoming request — parse the payload, validate the source (e.g., check a secret token), and execute the desired action.
5. Test end-to-end — trigger a real event and check that your endpoint receives and processes it correctly. Use a tool like Webhook.site (webhook testing tool) to inspect headers and body.

Using a tool like Zapier

• Zapier allows non-developers to set up webhooks via its “Catch Hook” trigger (Zapier (integration platform)).
• No coding required: provide a webhook URL, and Zapier parses the incoming payload and maps it to actions like creating a spreadsheet row or sending an email.

The catch: Creating a webhook from scratch requires a publicly accessible endpoint and handling of retries, security, and logging. Pre-built platforms like Zapier lower the bar, but understanding the underlying mechanism is key to debugging and customization.

“A webhook is a lightweight, event-driven communication that automatically sends data between applications via HTTP.”

— Red Hat (enterprise automation leader)

“Webhooks are automated messages sent from apps when something happens, delivered to a unique URL with a payload.”

— Zapier (integration platform)

Webhooks are the plumbing of real-time automation. For a developer or ops team building integrations, the choice between webhooks and APIs is no longer theoretical: it’s a daily decision that affects latency, scalability, and operational cost. The smart play is not to pick one — it’s to wire both together, letting webhooks cover the event-driven moments and APIs cover the on-demand queries. For any team managing more than three SaaS tools, ignoring webhooks means leaving automation on the table.