Tested Through: 5.7.7
The Uptime plugin allows you to check all your sites to see if they're online and get an alert (either push notification or email) to alert you that there is a problem. You will also get a follow up notification when the site comes back online. Sites do not have to be based on UserSpice to do a simple check, but a special UserSpice target file gives you some extra info like php version and UserSpice version. Requires a CRON job.