3rd Party Uptime Monitoring Services
You can sign-up a free service with below uptime monitoring as no charges.
1) CA Cloud Monitor - http://cloudmonitor.ca.com/en/dnstool.php
2) PingDom - http://tools.pingdom.com/fpt/
3) MangoXchange 24x7 Monitoring Tool - http://monitor.mangoxchange.com
4) Hetrixtools - https://hetrix.tools/u-995526
5) Uptimerobot - https://uptimerobot.com/
6) Pingzuo - https://pinguzo.com/