Google Chrome Developer Tools - Get started with Google Chrome's built-in web developer tools.
Charles - HTTP proxy / HTTP monitor / Reverse Proxy
HttpWatch - HttpWatch: The ultimate HTTP Sniffer for Chrome, IE and iOS
Postman - The Collaboration Platform for API Development
Omnibug - Omnibug is a plugin for the Google Chrome and Mozilla Firefox browsers to ease developing and...
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.