Nagios - Complete monitoring and alerting for servers, switches, applications, and services
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.
Gitwin - Enable your Windows system as a powerful and secure Git repository. Supports ssh, http(s) transports. Gitweb with highlighter and gravatar support available.
AppDynamics - Get real-time insight from your apps using Application Performance Management—how they’re being used, how they’re performing, where they need help.
NIXStats - SaaS monitoring tool for window/linux servers and websites. Think up-time robot but with more features.
Zabbix - Track, record, alert and visualize performance and availability of IT resources