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
Netumo - Ensure healthy website performance, uptime, and free from vulnerabilities. Automatic checks for SSL Certificates, domains and monitor issues with your websites all from one console and get instant notifications on any issues.
Lansweeper - Lansweeper discovers Windows, Linux and Mac machines in your network.
AppZero - AppZero is a monitoring and migration tool that allows users to keep track of different applications and servers in both simple and complex IT environments.
Nmap - Nmap Free Security Scanner, Port Scanner, & Network Exploration Tool. Download open source software for Linux, Windows, UNIX, FreeBSD, etc.
RedGate SQL Monitor - SQL Monitor helps you and your team find issues – before they become problems