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.
Ansible - Radically simple configuration-management, application deployment, task-execution, and multi-node orchestration engine
Snipe-IT - Managing assets with a Google doc or a shared Excel spreadsheet is more common than you think.
Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
Zabbix - Track, record, alert and visualize performance and availability of IT resources
Puppet Enterprise - Get started with Puppet Enterprise, or upgrade or expand.