Runscope - Log, monitor and measure your API usage to solve API problems fast.
Monitority - Simple website monitoring service (sms/email alerts)
Thunder Client - Rest API client for VS Code, lightweight Postman alternative
Oh Dear! - The all-in-one monitoring tool.
LoadFocus - Cloud Testing Infrastructure | Cloud Testing Services and Tools for Websites & APIs.
Suprvise - Know instantly when your sites are down.