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

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

jmxtrans

Plugs Java VM statistics via JMX to various backend monitoring tools

     

linux windows osx open-source monitoring java

KairosDB

KairosDB is a fast distributed scalable time series database written on top of Cassandra. RESTful JSON-based query/results. Includes flot-based visualization.

     

linux windows osx open-source metrics visualization java cassandra

Logstash

A modern tool for managing events and logs, with an ElasticSearch backend which allows a high degree of searching and filtering. It includes a shipper in remote systems, indexer in the aggregator machine, and a Web UI.

     

linux windows osx open-source monitoring java

Metrics

Captures JVM and application-level metrics for Java

     

linux windows osx open-source monitoring java

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

Sentry

Automate error tracking to find and fix issues before your users even experience a crash. Sentry is open-source, real-time, and loved by 100,000 developers around the world.

     

osx windows linux open-source errors nodejs ruby python php java monitoring

Zabbix

An open source, enterprise-class monitoring framework

     

linux windows osx open-source monitoring c