PAW (pro-active webfilter) is an Open-Source filtering HTTP proxy based on the Brazil Framework provided as a Open-Source Project by SUN. Because the Brazil Framework and PAW are written in Java the software is highly portable.
PAW allows for easy plugin of Handlers (filter outgoing requests) and Filters (filter incoming data - the HTML response) and a GUI for end users. All the configuration files are in XML-Format and thus easy to modify (even without the GUI).
See Other Best Ftp, Http, Email & Other Network Servers Projects in Java: