Unleash - Open source Feature toggle/flag service. Helps developers decrease their time-to-market and to increase learning through experimentation.
Charles Proxy - HTTP proxy / HTTP monitor / Reverse Proxy
LaunchDarkly - LaunchDarkly is a powerful development tool which allows software developers to roll out updates and new features.
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.
ConfigCat - ConfigCat is a developer-centric feature flag service with unlimited team size, awesome support, and a reasonable price tag.
Postman - The Collaboration Platform for API Development