ifttt - IFTTT puts the internet to work for you. Create simple connections between the products you use every day.
Prometheus - An open-source systems monitoring and alerting toolkit.
Zapier - Connect the apps you use everyday to automate your work and be more productive. 1000+ apps and easy integrations - get started in minutes.
Nagios - Complete monitoring and alerting for servers, switches, applications, and services
n8n.io - Free and open fair-code licensed node based Workflow Automation Tool. Easily automate tasks across different services.
StatsD - Simple daemon for easy stats aggregation.