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.
Zabbix - Track, record, alert and visualize performance and availability of IT resources
DCImanager - DCImanager is a platform for managing physical equipment. Connect any physical equipment to a single platform. Use the platform to manage your servers, switches, PDU as well as physical and virtual networks.
openITCOCKPIT - openITCOCKPIT is a leading open source monitoring framework based on Naemon (Nagios). In addition it integrates Checkmk and Prometheus. It also offers interfaces to Icinga2, PRTG and opManager to obtain status and performance from them.
Opendcim - a free, web based Data Center Infrastructure Management application.
Nagios - Complete monitoring and alerting for servers, switches, applications, and services