Cronitor - Monitor cron jobs, micro-services, daemons and almost anything else, no setup required. Easier cron troubleshooting and no more silent failures.
Web Uptime - Multi-location website uptime monitoring
Dead Man's Snitch - Monitor Cron Jobs and Windows Scheduled Tasks with ease.
Platypus - Realtime server monitoring and reporting
Cronhub - Cronhub helps you to easily monitor all your cron jobs in a beautiful dashboard. It alerts you when your cron job doesn't run on time or it fails.
Hyperping - Cheap uptime and performance monitoring with detailed reporting and flexible alerting