Admin Labs provides powerful monitoring and communication services for businesses.
RapidSpike - RapidSpike is an uptime and performance monitoring service for websites and web applications.
UptimeRobot - Free Website Uptime Monitoring
Monitis - Monitis specializes in IT monitoring, covering server, website, app monitoring and more within an all-in-one monitoring platform.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Raygun - Raygun gives developers meaningful insights into problems affecting their applications. Discover issues - Understand the problem - Fix things faster.
Site24x7 - Site24x7 offers both free & paid website monitoring services. Monitor websites remotely and receive instant email/sms alerts if your website becomes unavailable. View uptime & performance graphs of your website monitors.