See also: File sharing | Centralized Clients

Official home page: http://www.kazaa.com

Topic includes spyware-free version:

KaZaA Lite Ressurection Home Page: http://www.filesharingplace.com/startpage

KaZaA is a semi-centralized file sharing application originally developed by the Dutch company KaZaA BV. The KaZaA application quickly rose to popularity after the shutdown of Napster and Scour, both of which tried to create “legitimate” file sharing businesses. It allows sharing and searching for all types of files. The application has a built in Windows Media Player control and displays extensive metadata about search results.


Quick Facts

  • The current official version of KaZaA includes spyware and a controversial parallel P2P network called AltNet (see below) while the unofficial “lite” or “diet” version is hacked by an unknown individual to remove this spyware. KaZaA’s status towards this “lite” version is mixed but it is not known whether they persecute “lite” users.
  • KaZaA remains the most popular file sharing network, although DirectConnect rivals it in the amount of available files.
  • KaZaA is a specific application to access the network which is called FastTrack.


As KaZaA grew in popularity, its creators started licensing the software to other companies. Soon, KaZaA was repackaged under different names, such as Morpheus and Grokster. All of these were essentially the same application — the icons were changed, but in initial versions the programmers had even forgotten to change some texts so it still said “KaZaA” in some places. Another revenue opportunity for KaZaA BV was spyware (or, more neutrally, third party applications bundled with the software). Soon KaZaA clone Morpheus, which was spyware-free, became the preferred client for many users.

Meanwhile, the Dutch recording industry tried to get KaZaA shut down — a difficult task, given the fact that the client comes with a list of IP addresses of “supernodes” from all around the world and is therefore not directly dependent on a functioning mother company like its centralized cousin Napster. Nevertheless, a judge ordered KaZaA BV to shut down operation of the network in November 2001, an order the company found impossible to comply with.

In January 2002, the rights to the KaZaA application and trademark were surprisingly sold to an Australian company named Sharman Networks. The new owners swiftly made several controversial decisions:

  • Only one month after the takeover, Morpheus users were no longer able to connect to the network: A message box told them to upgrade their client. Apparently, protocol changes had made it inaccessible. Morpheus then switched to Gnutella-client Gnucleus as its software base and quickly declined into obscurity.
  • The Linux KaZaA client, only provided a few months earlier, was discontinued.
  • Additional third-party software / spyware was added to KaZaA.

Controversial AltNet

The biggest surprise came on April 1, a date which CNET reported that Sharman-related company Brilliant Digital had secretly added yet another application to KaZaA, this one being a completely separate P2P network called AltNet that would be used for “distributed computing” purposes of an as-of-yet undefined nature.

KaZaA clone Grokster remains operational, which lends credibility to the hypothesis that Morpheus was locked out because they failed to pay their bills. There are several hacked versions of KaZaA which do not include the spyware, most prominent among them Kazaalite. Whether or not operation of such a hacked client is legal depends on your local laws (it can be interpreted as “theft of service”). Even if the use is illegal, only the distribution of the hacked client is likely to be prosecuted. (Ironically, it can also be found on KaZaA itself.)

The technology behind KaZaA is called FastTrack (see also FastTrack homepage), and thus KaZaA and its clones are often referred to as “FastTrack-based” or “the FastTrack stack”. See FastTrack for further details about the file sharing protocol and the giFT project (which originally had the goal to develop a FastTrack-compatible client).

Related Software


TakeDown.NET -> “KaZaA