Concept / Term · Established
Event-driven HTTP callback
An automatic HTTP message sent to another system when a subscribed event happens, avoiding repeated polling for updates.
Field note
A webhook is an HTTP callback sent when an event occurs. Instead of repeatedly asking whether something changed, the receiving system exposes an address and waits to be notified.
The name combines “web” with the programming idea of a hook—a point where another process can attach behaviour. It is often described as a reverse API call.
Payment platforms, code hosts and SaaS products send signed webhook requests for events such as a completed payment or merged pull request.
Webhooks make integrations timely and efficient, but receivers must authenticate requests and safely handle retries.
In a sentence“When the invoice is paid, the provider’s webhook updates the customer account.”