Zabbix - Track, record, alert and visualize performance and availability of IT resources
Nagios - Complete monitoring and alerting for servers, switches, applications, and services
Observium - Observium
Gitwin - Enable your Windows system as a powerful and secure Git repository. Supports ssh, http(s) transports. Gitweb with highlighter and gravatar support available.
NIXStats - SaaS monitoring tool for window/linux servers and websites. Think up-time robot but with more features.
Icinga - Icinga is a fork of Nagios and is backward compatible.