NetBox - NetBox is an open source web application designed to help manage and document computer networks. NetBox was developed specifically to address the needs of network and infrastructure engineers.
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.
Snipe-IT - Managing assets with a Google doc or a shared Excel spreadsheet is more common than you think.
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.
Zabbix - Track, record, alert and visualize performance and availability of IT resources
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.