Nagios - Complete monitoring and alerting for servers, switches, applications, and services

Netdata - Monitor your servers, containers, and applications, in high-resolution and in real-time.

Gitwin - Enable your Windows system as a powerful and secure Git repository. Supports ssh, http(s) transports. Gitweb with highlighter and gravatar support available.

eZ Server Monitor - eZ Server Monitor is a script for monitoring Linux servers.

LANState - LANState - Network Mapper and Device Monitor

Grafana - Data visualization & Monitoring with support for Graphite, InfluxDB, Prometheus, Elasticsearch and many more databases