dradis - Dradis is the open-source reporting and collaboration tool for IT security professionals.
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.
Lampyre - Lampyre - an efficient data analysis and OSINT multi-tool for everyone.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Netglub - Netglub, the really open source information gathering solution.
Better Uptime - We call you when your website goes down