Google Chrome Developer Tools - Get started with Google Chrome's built-in web developer tools.
UMLGraph - UMLGraph is a professional automated drawing tool that allows the designers the declarative specification and drawing of UML class and sequence diagram.
Omnibug - Omnibug is a plugin for the Google Chrome and Mozilla Firefox browsers to ease developing and...
yEd - yEd is a free desktop application to quickly create, import, edit, and automatically arrange diagrams. It runs on Windows, Mac OS X, and Unix/Linux.
Fiddler - Fiddler is a debugging program for websites.
Dia - Dia is a GTK+ based diagram creation program for GNU/Linux, MacOS X, Unix, and Windows, and is released under the GPL license.