Zabbix - Track, record, alert and visualize performance and availability of IT resources
Total Network Inventory - Total Network Inventory is a piece of software designed to help with managing software inventory and auditing PC systems.
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.
Lansweeper - Lansweeper discovers Windows, Linux and Mac machines in your network.
Prometheus - An open-source systems monitoring and alerting toolkit.
Kuwaiba - Kuwaiba is an open source, enterprise grade network inventory and CMDB for your telecommunications and IT infrastructure