What is a Webhook? How Real-Time Push Integrations Work
A webhook is an HTTP callback that pushes data from one system to another the moment an event occurs — no polling required. Learn how webhooks work, how to secure them, and where they fit in enterprise automation.
What is Webhook?
A webhook is an event-driven mechanism that allows one application to automatically send data to another the moment a specific event occurs. Instead of polling an API repeatedly to check for changes, the source system pushes an HTTP POST request to a URL you specify — your webhook endpoint — the instant the event fires. Webhooks are sometimes called 'reverse APIs' because data flows from the source to you, not the other way around.
- Event-driven: data is pushed immediately when an event fires
- Eliminates polling — reduces unnecessary API calls and latency
- Delivered as an HTTP POST request to a pre-configured URL
- Payload is typically JSON describing the event and affected resource
- Also called 'HTTP callbacks' or 'reverse APIs'
How Webhook Works
You register a webhook by providing the source system with a URL — your endpoint. When the configured event occurs (a payment completes, a ticket is created, a form is submitted), the source makes an HTTP POST to that URL with the event data. Your server processes the payload and returns HTTP 200 to acknowledge receipt.
Register the endpoint
Provide the source system (Stripe, GitHub, Salesforce) with a publicly accessible HTTPS URL that will receive POST requests.
Configure trigger events
Select which events you want to receive — for example, payment.completed, pull_request.opened, or lead.created — in the source system's webhook settings.
Event fires → POST request sent
When the trigger condition is met, the source system sends an HTTP POST to your URL with a JSON body describing the event and its data.
Verify, process, acknowledge
Validate the HMAC signature in the request header to confirm authenticity, process the payload asynchronously, and return HTTP 200 to acknowledge receipt within a few seconds.
Common Webhook Use Cases
Payment and subscription events
Stripe sends a webhook when a subscription renews — your system updates the customer record and triggers a receipt email without any polling.
CI/CD pipeline triggers
GitHub fires a webhook on every pull request or push, triggering automated tests, builds, or deployment pipelines downstream.
Real-time agentic triggers
FlowGenX listens on a webhook endpoint for events from Zendesk, HubSpot, or Shopify and immediately launches a multi-step agentic workflow to classify, route, or resolve the event.
Webhook in FlowGenX AI
FlowGenX provides built-in webhook listeners with unique, configurable endpoint URLs per workflow. Every incoming webhook is automatically validated (HMAC signature verification), parsed, and used as a workflow trigger — no custom server code needed. Failed deliveries are retried with exponential backoff. You can inspect full payloads in the audit log and branch workflow logic based on any field in the event body.
Frequently Asked Questions
See It In FlowGenX