I’ll introduce the external network HTTP(S) uptime monitoring service Pingdom.
This service
You can use one site, one check for free, so I set up uptime monitoring for my personal site. (It’s no longer available for free)
If you want to use it for free, register as a new member from the URL https://www.pingdom.com/free/.
As of March 17, 2015, there’s no mention of a free plan on the Monitoring pricing page, but when you register from https://www.pingdom.com/free/, it seems you can use it for free with only one monitoring target.
For those who want to introduce site uptime monitoring as easily as possible, Pingdom has a free plan, so you can try it out first, which I recommend.
That’s all from the Gemba, where I introduced the external network HTTP(S) uptime monitoring service Pingdom.