Netdata is an open-source real-time monitoring & troubleshooting tool that only requires a few steps to get installed. The Git repository comes with an automated script that handles the bulk of the installation and configuration process and takes away the cumbersome configuration associated with other monitoring tools.
Netdata has become hugely popular since its initial release in October 2013. It collects real-time metrics such as CPU and RAM usage, bandwidth statistics, and disk utilization and displays them on easy-to-interpret charts/graphs.