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.
Detectify - Detectify provides a user friendly and thorough web security scan that allows you to focus 100% on web development.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Burp Suite - Burp Suite is an integrated platform for performing security testing of web applications.
Better Uptime - We call you when your website goes down
Transmit iOS - Upload/download from a private server, website, or S3 in iOS