The first public version was released in 2003, at a time when the music industry started to sue individual file sharing users (a change from its previous stance that it would not target consumers with copyright infringement lawsuits).

[6] The original PeerGuardian (1.0) was programmed in Visual Basic and quickly became popular among P2P users despite blocking only the common TCP protocol and being known for high RAM and CPU usage when connected to P2P networks.

Speed and resource inefficiencies were fixed by re-designing and re-coding Version 2.0 in C++ to consume less processing power and memory.

Unfortunately this meant that lists became very large and cost a lot of bandwidth to distribute, heralding the construction of the smaller binary formats.

With this database the admins of the site (Seraphielx, Moore, Firstaid, Tozanno, DeathAngel, R00ted) would search for names of Anti-P2P companies and set a status code in the entry to make the blocklists that would be downloaded by the blocklist manager for import into PeerGuardian, Protowall, and other applications that would block Anti-P2P traffic from accessing your download.

They would also obtain logs from people who were sent letters for downloading "illegal" software, music and videos and figure out who in the list did not belong and flag the entry just to be safe.

With the blocklist manager application, users can add these sites to a "Safe list" allowing them to continue using the Games and websites without interference from PeerGuardian.

In 2007, Bluetack/PeerGuardian 2 were criticized for blocking denis.stalker.h3q.com, the second largest BitTorrent tracker as of December 2007, as an "Anti-P2P" address, and claiming that its maintainers (whose tracking software "Opentracker" is also used by The Pirate Bay) were conspiring with the MPAA and MediaDefender.

Critics have pointed out that the blocklists are open to the public, and thus parties who may wish to circumvent PeerGuardian can actively check the list to see if their IP addresses have been blocked.