ApexSQL Monitor - SQL Server performance monitor - Monitor, detect, and solve SQL Server performance problems on any device
Zabbix - Track, record, alert and visualize performance and availability of IT resources
RedGate SQL Monitor - SQL Monitor helps you and your team find issues – before they become problems
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.
Visual Expert - An all-in-one Static Code Analysis + SAST tool for PowerBuilder, Oracle and SQL Server
Prometheus - An open-source systems monitoring and alerting toolkit.