Apache Tomcat - An open source software implementation of the Java Servlet and JavaServer Pages technologies
Zabbix - Track, record, alert and visualize performance and availability of IT resources
nginx - A high performance free open source web server powering busiest sites on the Internet.
Datadog - See metrics from all of your apps, tools & services in one place with Datadog's cloud monitoring as a service solution. Try it for free.
vCenter Server - IaaS platform for managing and deploying virtual machines
Prometheus - An open-source systems monitoring and alerting toolkit.