What is Webhook?
Definition
A webhook is an automatic message one application sends to another over the web the moment a specific event happens, such as a payment succeeding or a form being submitted, so the receiving system can react without having to keep asking for updates.
Last updated 2026-10-18 · Flowmatix
How a webhook works
You give the sending system a URL on your side, called an endpoint, and choose which events you care about. When one of those events happens, the sender makes an HTTP POST request to that URL with the details, usually as JSON. Your endpoint reads the data and does something with it.
The alternative is polling: asking another system every few minutes, "anything new?". Webhooks flip that around. It is the difference between refreshing a delivery tracking page and getting a text when the parcel arrives.
Example: a yoga studio takes payments through Stripe. When a class pack purchase succeeds, Stripe sends a payment_intent.succeeded webhook to the studio's booking system, which adds credits to the member's account, emails a receipt and updates the CRM, all within seconds.
Stripe's webhook documentation illustrates the practical rules most providers share: verify each request's signature so attackers cannot send fake events, return a success response quickly before doing heavy work, and expect duplicates and out-of-order delivery. Stripe retries failed deliveries in live mode for up to three days.
Why it matters for your business
Webhooks are the glue of modern business automation. They let a payment, a booking, a signed contract or a new lead trigger the next step instantly instead of waiting for someone to notice. That cuts manual data entry and the delays that frustrate customers.
They are also efficient: systems only communicate when something actually changes, which keeps integrations fast and inexpensive to run.
Common mistakes
- Not verifying signatures, so anyone who finds the URL can trigger actions like fulfilling orders.
- Doing slow work before responding, causing timeouts and repeated retries.
- Processing the same event twice because duplicates were not tracked by event ID.
- Assuming events arrive in order.
- No logging or alerts, so failed deliveries go unnoticed until a customer complains.
Frequently asked questions
What is the difference between a webhook and an API?
With an API, your system asks for data when it wants it. With a webhook, the other system pushes data to you when an event happens. Most integrations use both. Our API integration entry explains the wider picture.
Do I need a developer to use webhooks?
Not always. Tools like Zapier, Make and n8n can receive webhooks without code. Our comparison of automation tools covers when custom code becomes worthwhile.
Are webhooks secure?
They can be, with HTTPS, signature verification and minimal data in each payload.
How Flowmatix can help
Our API integration work puts this into practice for businesses in Toronto and around the world. Get a personalised quote in about 3 minutes.
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