SwiftDefaultApps - Replacement for RCDefaultApp, written for macOS Sierra, in Swift 3.
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.
FileMenu Tools - FileMenu Tools lets you customize the context (right-click) menu of Windows Explorer.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
RCDefaultApp - RCDefaultApp is a Mac OS X 10.
Better Uptime - We call you when your website goes down