A heartbeat monitor is a simple up/down alert that can be set up for your services(s). It creates an alert if a POST request is not received within the time window that you configure.
For example let’s say you have a critical node in some environment and want to receive an alert if this node is unavailable for 15 consecutive minutes.
In your GoAlert Service, you can click on the Heartbeat Monitor, and then set the timeout to 15 minutes. Copy the heartbeat URL that it creates. On your critical node, run a process to POST to the heartbeat URL every minute or two. If GoAlert does not receive a single POST request in the 15 minute window, an alert will be created against your service and your team will be notified according to your escalation policy.