Muffin - a filtering proxy server for the World Wide Web.

Features:

* Written entirely in Java.  Requires JDK 1.1
  Runs on Unix, Windows 95/NT, and Macintosh.

* Freely available under the GNU General Public License.

* Support for HTTP/0.9, HTTP/1.0, HTTP/1.1, and SSL (https).

* Graphical user interface and command-line interface.

* Remote admin interface using HTML forms.

* Includes several filters which can remove cookies, kill GIF
  animations, remove advertisements, add/remove/modify arbitrary
  HTML tags (like blink), remove Java applets and Javascript,
  user-agent spoofing, rewrite URLs, and much more.

* View all HTTP headers to aid in CGI development and debugging.

* Users can write their own filters in Java using the provided
  filter interfaces.

Download sites:

    http://muffin.doit.org/
    ftp://muffin.doit.org/pub/muffin/