I also use Healthchecks.io. Originally i self hosted it, but their free plan is more than generous enough for my needs (20 jobs monitored for free i think). B

I also use Healthchecks.io. Originally i self hosted it, but their free plan is more than generous enough for my needs (20 jobs monitored for free i think). Besides monitoring backups and cron jobs, i use it for monitoring the power state of my summerhouse. We had a problem with a breaker that would trip for no reason, and since nobody wants to arrive at a summerhouse where the fridge has been unpowered for a couple of weeks, i put a RPi Zero W up there on the circuit of the problematic breaker, and set it to call Healthchecks every 15 minutes. If it misses 2, i (might) have a problem. So far the alarm has gone off twice, both times (fortunately) internet connection releated.