Zabbix - Track, record, alert and visualize performance and availability of IT resources
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.
Statista - The Statistics Portal for Market Data, Market Research and Market Studies
Nagios - Complete monitoring and alerting for servers, switches, applications, and services
Montecarlito - MonteCarlito is a free Excel-add-in to do Monte-Carlo-simulations.
LogicMonitor - LogicMonitor is the SaaS performance monitoring platform for the world's best IT teams. Deploy Fast, Monitor More, Improve Ops.