Webhook

A standard API call is pull-based: a system has to ask, "has anything changed?" — usually on a timer, which means there's always some delay between an event happening and a system finding out about it, and wasted requests asking when nothing changed. A webhook is push-based: the moment a defined event occurs (a form submission, a payment completing, a deal stage changing), the source system immediately sends the data to a pre-registered endpoint, with no polling delay.

This makes webhooks the standard mechanism behind most real-time integrations — a payment processor notifying a CRM the instant a purchase completes, or a form tool notifying an automation platform the instant a lead submits, both typically run on webhooks rather than a system periodically checking for new records.

Because a webhook is a one-way push with no built-in retry guarantee unless both systems implement one, a webhook endpoint that's down when an event fires can silently lose that event — which is why reliable automation builds log every webhook received and reconcile against the source system periodically, rather than trusting the push alone as the only record.