HttpWatch : An HTTP Viewer and HTTP Sniffer for IE and Firefox
Wireshark : 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 fac...
toxy : toxy is a fully programmatic and hackable HTTP proxy to simulate server failure scenarios and unexpected network conditions, built for node.js/io.js.
LibreNMS : A fully featured network monitoring system that provides a wealth of features and device support.
OpenDNS : The safest, smartest, fastest and most reliable DNS on the planet.