WebCargo - Optimize your workflow by offloading it to us. Useful API's with seamless integration that scale to your needs.
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.
WhoisThisDomain - Domain name lookup tool that allows you to get information about domain registration from WHOIS server.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Whoisology - Connected database of whois records and whois history
Better Uptime - We call you when your website goes down