i3 - A dynamic tiling window manager designed for X11, inspired by wmii, and written in C.
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.
dwm - dwm is a dynamic window manager for X. It manages windows in tiled, monocle and floating layouts. All of the layouts can be applied dynamically, optimising the environment for the application in use and the task performed.
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.
Openbox - Openbox is a highly configurable, next generation window manager with extensive standards support.
Zabbix - Track, record, alert and visualize performance and availability of IT resources