Radio Silence - Radio Silence is a network monitor and firewall for the macOS. The software stops apps from making network connections. The firewall runs in the background and does not require an open window.
Platypus - Realtime server monitoring and reporting
Application Monitor - Application Monitor is a program that constantly checks the processes previously chosen by the...
Datadog - See metrics from all of your apps, tools & services in one place with Datadog's cloud monitoring as a service solution. Try it for free.
Restart on Crash - Automatically Restart Crashed Or Hanged Applications
Nagios - Complete monitoring and alerting for servers, switches, applications, and services