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

jclouds

A Java Library for controlling cloud resources, with various plugins for many popular cloud providers.

     

linux windows osx open-source cloud-paas java

jmxtrans

Plugs Java VM statistics via JMX to various backend monitoring tools

     

linux windows osx open-source monitoring java

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

Monit

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

     

linux osx open-source monitoring process-mgmt 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

testssl.sh

A command-line tool which checks a server's service on any port for the support of TLS/SSL ciphers, protocols as well as some cryptographic flaws. It's designed to provide clear output for your "is this good or bad" decision.

     

linux osx open-source security shell

Zabbix

An open source, enterprise-class monitoring framework

     

linux windows osx open-source monitoring c