Zabbix - Track, record, alert and visualize performance and availability of IT resources
Goliath Performance Monitor - Goliath Performance Monitor is proactive, end-to-end IT performance monitoring for Citrix & VMware to ensure a positive end user experience. Try it free!
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.
Server Density - Trusted monitoring built by experts.
Nagios - Complete monitoring and alerting for servers, switches, applications, and services
Observium - Observium