Majestic Uptime Mech Overlord Zero Suit RX-0 will help you monitor your websites via the Uptime Robot service. View all your monitors at once, set check intervals, and get browser notifications when your sites are down–beep, boop, beep!
This extension requires an Uptime Robot account at https://uptimerobot.com/
This is the best extension for Uptime Robot. It shows everything you need at a quick glance and the notifications you receive to let you know when a site is down is very helpful! Also; the artwork and name for this extension is hella rad.