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

M/Monit - Monit is a free open source utility for managing and monitoring, processes, files, directories and filesystems on a UNIX system. Monit conducts automatic maintenance and repair and can execute meaningful causal actions in error situations.

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.