RPi-Monitor - RPi-Monitor is a tool that provides all the connected system peripherals properties and current metrics.
Pingdom - With website monitoring from Pingdom you will be the first to know when your website is down. No installation required. 30-day free trial.
Venmon - Compact size system resources monitoring utility and multi-ping tool for Windows
Scout - Scout ♥ monoliths.
Checkmk - Checkmk - the software for effective IT monitoring
Wachete - Track web page changes and get notified. Free Sign-up. Have all data in one place