How does a webhook work?
You register a URL — the endpoint — with the system that holds the data, and tell it which events you care about. When one of those events fires, that system sends an HTTP POST to your endpoint with a payload describing what happened, usually JSON. Your server reads the payload, does its work, and returns a 2xx status to acknowledge receipt. No request from you triggered it — the source acted on its own. Most providers sign each request so you can confirm it genuinely came from them.
Webhook vs API polling: what is the difference?
Polling is the pull model: your code asks an API 'anything new?' on a fixed schedule, whether or not anything changed. A webhook is the push model: the source calls you only when there is something to report. Polling wastes most of its requests and adds lag between the event and your reaction; webhooks deliver within seconds and stay quiet otherwise. The trade-off is that your endpoint has to be publicly reachable and ready to handle bursts.
How do engagement platforms use webhooks?
- Outbound — a webhook node inside a journey POSTs to an external system mid-flow: notify Slack when a lead converts, sync a status to your CRM, kick off a fulfilment step.
- Inbound — a receiver ingests events from other tools: a payment provider reports a successful charge, a form tool passes a new lead, so profiles and journeys react without a nightly import.
- This two-way plumbing is what lets a customer engagement platform sit in the middle of your stack. Dedicated delivery services such as Knock specialise in the outbound side alone.
Why it matters for a small team
A two-person team cannot sit and poll for changes, and cron jobs that check every few minutes add both lag and cost. Webhooks let one tool react to another the moment something happens, with no one watching. Two cautions: because any caller can POST to a public URL, verify the signature on every request and treat the body as untrusted; and log the events you emit and receive so they line up with your tracking plan instead of becoming an untracked side channel.