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.
GlassWire - Visualize network activity in detail, get notified when new apps access the network, look out for...
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
TrafficMonitor - TrafficMonitor is a network monitoring suspension window software in Windows.
Better Uptime - We call you when your website goes down
NetWorx - NetWorx is a simple and powerful tool that helps you objectively evaluate your bandwidth situation.