Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
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.
WhatsApp Desktop - WhatsApp, now on your desktop
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Wafer Messenger - Endless Creativity, Limitless Reach.
Better Uptime - We call you when your website goes down