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

Rex

A agent-less server orchestration tool built on Perl

     

linux windows osx open-source orchestration perl

Statman

Statman makes it possible to instrument and collect statistics from your high-traffic production Erlang systems with very low overhead. The collected data points are aggregated in the VM and can be sent to services like Graphite, Munin, New Relic, etc.

     

linux windows osx open-source monitoring erlang

Zabbix

An open source, enterprise-class monitoring framework

     

linux windows osx open-source monitoring c