Web & SaaS
What is Webhook?
Definition
An automated HTTP notification sent from one application to another when a specific event occurs — the 'push' alternative to polling an API for updates.
In more detail
A webhook is a mechanism where one system automatically notifies another when something happens. Rather than your application constantly asking a third-party service 'has anything changed?' (polling), the third-party service proactively sends your application an HTTP request the moment an event occurs. Webhooks are often described as 'reverse APIs' for this reason.
Common webhook use cases: a payment processor notifying your app when a payment is confirmed, a form tool sending lead data to your CRM the moment someone submits a form, a CI/CD system triggering a deployment when code is pushed to a repository, or an AI pipeline receiving real-time data from an external system to trigger an automated workflow.
Webhooks require careful security implementation. The receiving endpoint should validate a cryptographic signature (provided by the sender) to confirm the request is genuine and not a spoofed request from a malicious actor. They should also be idempotent — designed to handle the same event being delivered more than once without causing duplicate actions.
Why it matters
Webhooks are how modern business software talks to itself in real time. Understanding them is essential when evaluating software integrations, building automation workflows, or designing systems that need to react to events as they happen rather than on a schedule.
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