NIXStats - SaaS monitoring tool for window/linux servers and websites. Think up-time robot but with more features.
Scout - Scout ♥ monoliths.
Server Monitoring - A server monitor is a tool that monitors your server and website on close intervals and reports to you if it's inaccessible.
AppOptics - Application performance management and infrastructure monitoring.
Nodeping - NodePing Server Monitoring and Web Site Monitoring. Simple but powerful Internet service monitoring.
CXGuardian - CXGuardian is a platform powered by QualityKiosk Technologies and allows users to monitor their mobile and web-based applications’ performance.