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

ConDep

ConDep is a open source infrastructure configuration and deployment DSL (Domain Specific Language) specifically targeted to (but not limited to) the Windows Server platform. If your familiar with tools like Chef and Puppet, ConDep does very much the same, but with native support for Windows.

     

windows open-source ci provisioning config-mgmt net

Instrumental

Instrumental is a real-time, high-scale application and server monitoring tool with intelligent alerts, a powerful query language, and free development accounts.

     

linux windows oxs free metrics commercial metrics monitoring visualization php ruby python net java nodejs

Zabbix

An open source, enterprise-class monitoring framework

     

linux windows osx open-source monitoring c