collectd
A daemon that collects system performance statistics periodically, and provides tons of plugins to store and analyze these values
linux windows osx open-source monitoring c
Nagios Core
Nagios Core network monitoring software is a powerful, enterprise-class host, server, application, monitoring and alerting tool
linux solaris bsd open-source monitoring c
Pallet
A tool to provision and maintain servers across various cloud platforms as well as virtual machine platforms, without any dependencies. Provides cloud and operating system independence.
linux windows osx open-source cloud-paas clojure
PowerShell Desired State Configuration
DSC is a new management platform in Windows PowerShell that enables deploying and managing configuration data for software services and managing the environment in which these services run.
linux windows powershell open-source commercial config-mgmt
Zabbix
An open source, enterprise-class monitoring framework
linux windows osx open-source monitoring c