A friend and I launched https://cronitor.io last week (https://news.ycombinator.com/item?id=7917587). It's a simple cron/scheduled jobs monitoring and alerting tool.

We built it after trying to use a similar tool, but were unhappy with the types of alerts we could set.

It's still in its infancy, but we have a couple of paying customers and are trying to get feedback from as many people as we can. If anyone has a few minutes to look it over and offer feedback I'd greatly appreciate it!