Total Network Inventory - Total Network Inventory is a piece of software designed to help with managing software inventory and auditing PC systems.
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.
Lansweeper - Lansweeper discovers Windows, Linux and Mac machines in your network.
Snipe-IT - Managing assets with a Google doc or a shared Excel spreadsheet is more common than you think.
Spiceworks Help Desk - Help desk software features that work for IT
Zabbix - Track, record, alert and visualize performance and availability of IT resources