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

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

Zabbix

An open source, enterprise-class monitoring framework

     

linux windows osx open-source monitoring c

Zipkin

A distributed request tracking system, useful for micro-service and distributed architectures written in Scala

     

linux windows osx open-source monitoring scala