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.
logstash - logstash is a tool for managing events and logs.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Elk - The fastest way to convert currencies on mobile.
Better Uptime - We call you when your website goes down
Papertrail - Frustration-free log management. Get started in seconds.