UptimeRobot - Free Website Uptime Monitoring
NetSpeedMonitor - NetSpeedMonitor is a lightweight Network Monitoring Toolbar for your Windows Taskbar
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.
TrafficMonitor - TrafficMonitor is a network monitoring suspension window software in Windows.
Uptime Kuma - A fancy self-hosted monitoring tool.
GlassWire - Visualize network activity in detail, get notified when new apps access the network, look out for...