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.
Raygun - Raygun gives developers meaningful insights into problems affecting their applications. Discover issues - Understand the problem - Fix things faster.
Zabbix - Track, record, alert and visualize performance and availability of IT resources
Sentry.io - From error tracking to performance monitoring, developers can see what actually matters, solve quicker, and learn continuously about their applications - from the frontend to the backend.
Wireshark - Wireshark is a network protocol analyzer for Unix and Windows. It lets you capture and interactively browse the traffic running on a computer network.
RabbitMQ - RabbitMQ is an open source message broker software.