Performance Monitoring tools like Performance Co-Pilot (PCP) existed almost longer than the World Wide Web. It was developed in the early 90s by SGI. Parts were made available open source from 2000 on, which led to a further spread of the tool. In recent years an active community formed and a variety of new features and enhancements were added. PCP is now part of Red Hat and SuSE Linux Enterprise editions and included in many other Linux distributions. Versions for other Unix variants, OS X and Windows also exist. This session compares popular Open Source Monitoring Tools like Performance Co-Pilot, StatsD, Dropwizard Metrics, Prometeus, MicroProfile Metrics or StatsD. How they each support Containers or Virtualization, share data with IT monitoring systems like Nagios or Zabbix, or process analyze and visualize it via Carbon, Graphite or Grafana/ElasticSerch.