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.
VisualVM - VisualVM is a visual tool integrating several commandline JDK tools and lightweight profiling...
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Valgrind - Valgrind is an instrumentation framework for building dynamic analysis tools.
Better Uptime - We call you when your website goes down
dotMemory - dotMemory allows users to analyze memory usage in a variety of .NET and .NET Core applications.