The filters utilize a "matching" language similar to the standard regular expressions used in text editing.

Use of the program requires knowledge of the Proxomitron scripting language, and some familiarity with at least one of HTTP, HTML, JavaScript, and CSS.

The May 2003 release of Naoko 4.5 was followed very quickly by the removal of the program's web site and Lemmon's declared termination of continued development of Proxomitron.

[5] A subsequent release, however, was made in June 2003, primarily to revert a new behavior related to remote proxy connections that had been designed into the May version.

Lemmon's mirror redirect[broken anchor] was changed to display a different final message from the author a short time later.

Many current browsers do contain features similar to those provided by Proxomitron filters – blocking advertisements and pop-ups, for example.