Acunetix - Audit your website security and web applications for SQL injection, Cross site scripting and other...
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.
Intruder - Intruder is a security monitoring platform for internet-facing systems.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Horangi - Horangi is a leading cyber-security solution that provides instant response and threat detection for companies who lack the time and expertise to monitor their system.
Better Uptime - We call you when your website goes down