Total Network Inventory: Professional PC audit and network inventory management software - fits best for a for companies of all sizes. Free for 60 days.
Network Inventory Advisor - Network Inventory Advisor audits all network software and hardware simply and efficiently
Ansible - Radically simple configuration-management, application deployment, task-execution, and multi-node orchestration engine
Lansweeper - Lansweeper discovers Windows, Linux and Mac machines in your network.
Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
Nmap - Nmap Free Security Scanner, Port Scanner, & Network Exploration Tool. Download open source software for Linux, Windows, UNIX, FreeBSD, etc.
Puppet Enterprise - Get started with Puppet Enterprise, or upgrade or expand.