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.
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.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Service Uptime - Free website monitoring service checks your site from worldwide locations and alerts you instantly via email or SMS when it becomes unavailable. Detailed uptime statistics and performance reports available.
Better Uptime - We call you when your website goes down
Monitis - Monitis specializes in IT monitoring, covering server, website, app monitoring and more within an all-in-one monitoring platform.