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...
HttpWatch : An HTTP Viewer and HTTP Sniffer for IE and Firefox
Goutte : Goutte is a screen scraping and web crawling library for PHP.
Goutte provides a nice API to crawl websites and extract data from the HTML/XML response...
Sagui : Modern front-end development made easy. Sagui is all about good defaults. It is the single development dependency you need to worry about, taking care...
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 functional tests or even on a real deployment through the command-line.