What Is a Webhook? How Webhooks Work in Monitoring

Most integrations between services work by polling, asking "anything new?" over and over. Webhooks flip that model. Instead of your system checking for updates every few seconds, the source service sends an HTTP POST to a URL you specify the moment something happens. No wasted requests, no delay waiting for the next poll cycle.

A webhook is an HTTP callback (sometimes called a reverse API) that fires an automated POST request to a URL you've registered when a specific event occurs. A payment succeeds, a form is submitted, a monitor goes down, the source server sends you a JSON payload, your server acts on it. The whole exchange takes milliseconds and requires no authentication handshake beyond whatever verification you set up on your end.

How webhooks differ from APIs

A traditional API is pull-based: your code calls an endpoint, gets a response, and decides what to do with it. A webhook is push-based: the remote service calls your endpoint when it has something to say. APIs give you control over timing but cost you polling overhead. Webhooks give you speed but require you to have a publicly accessible endpoint ready to receive requests.

In practice, most services offer both. You use the API when you need to fetch data on demand, and webhooks when you need to react to events as they happen: payment confirmations, deployment triggers, alert notifications.

Webhooks in monitoring

Monitoring tools use webhooks as an event-driven alert delivery channel. When a check fails, the monitoring service sends a POST request to your endpoint with details about what went down, when, and what the error was. From there, your system can create a ticket, trigger a deployment rollback, page someone on call, or log the event, whatever your workflow needs.

WatchCron supports webhook notifications on every plan, including the free tier. When an uptime check fails or a cron job misses its schedule, the webhook fires in real time with a JSON payload containing the monitor name, status, timestamp, and error details. This makes it straightforward to wire WatchCron into any system that can receive HTTP requests: custom dashboards, ChatOps bots, incident management pipelines.

Related terms: health check, observability, status page, SLA