HttpWatch : An HTTP Viewer and HTTP Sniffer for IE and Firefox
Vaurien : Vaurien is basically a Chaos Monkey for your TCP connections. Vaurien acts as a proxy between your application and any backend.
You can use it in your...
namebench : namebench hunts down the fastest DNS servers available for your computer to use. namebench runs a fair and thorough benchmark using your web browser h...
Sitespeed.io : Sitespeed.io is an open source tool that helps you analyze and optimize your website speed and performance based on performance best practices. It col...
Wireshark is the world's foremost network protocol analyzer. It lets you see what's happening on your network at a microscopic level. It is the de facto (and often de jure) standard across many industries and educational institutions.