I used a few monitoring tools (mostly free ones to be honest) and found they were grand, but being free they did not provide much info.

Robotalp is the type of tool that you don't know you need until you use it. What I mean is that you may never even know your site was down. But with this tool you get immediate info if your site goes down (which one of mine did just yesterday)

it's super simple to use and is something that you need (even if you don't think you do!)

Grab this before it's too late