AWS Shield - AWS Shield is a managed Distributed Denial of Service (DDoS) protection service that safeguards web applications running on AWS.
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.
Rapid7 Nexpose - Network vulnerability and risk management solution.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
NetVizura EventLog Analyzer - EventLog Analyzer is practical solution that collects and archives huge amount of Syslogs and SNMP traps.
Better Uptime - We call you when your website goes down