Zabbix - Track, record, alert and visualize performance and availability of IT resources
Loader.io - Loader.io is a simple cloud-based load testing service
Datadog - See metrics from all of your apps, tools & services in one place with Datadog's cloud monitoring as a service solution. Try it for free.
WebLOAD - WebLOAD - The most flexible and cost effective software for enterprise load, stress and performance testing, integrated with DevOps processes. Click for details
Prometheus - An open-source systems monitoring and alerting toolkit.
StresStimulus - Load testing tool for websites and mobile that works with hard-to-test applications.