Hyperping - Cheap uptime and performance monitoring with detailed reporting and flexible alerting
Trello Calendar Connector by Cronofy - See and Organize your Trello deadlines inside your calendar
UptimeRobot - Free Website Uptime Monitoring
Bringschuld - Simple periodic task and email monitoring
Simple Ops - Simplify website performance and uptime monitoring with alerting, ssl check, chrome ux metrics, multi locations
Cronitor - Monitor cron jobs, micro-services, daemons and almost anything else, no setup required. Easier cron troubleshooting and no more silent failures.