collectd

A daemon that collects system performance statistics periodically, and provides tons of plugins to store and analyze these values

     

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Instrumental

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

     

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jmxtrans

Plugs Java VM statistics via JMX to various backend monitoring tools

     

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KairosDB

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

     

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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.

     

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Metrics

Captures JVM and application-level metrics for Java

     

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Monit

An open source utility for managing and monitoring processes, programs, files, directories and filesystems

     

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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.

     

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Zabbix

An open source, enterprise-class monitoring framework

     

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