UseModWiki
- A single-file implementation of the original Wiki concept created by WardCunningham. With flatfile database and numerous patches to extend feature set.
- http://www.usemod.com/cgi-bin/wiki.pl?UseModWiki

TWiki.org
- Heavily featured variant, with revision control, templates, category tables, authorization based on groups, automatic email notification of changes, file attachments.
- http://twiki.org/

TMNetWiki
- Modularized descendant of UseModWiki with limited weblog support, used on Technomanifestos.net (GPL).
- http://www.technomanifestos.net/?The_Network/Source

Kwiki
- A wiki engine designed for modularity and easy installing.
- http://www.kwiki.org/

Chiq_Chaq
- A wiki clone "for regular people", based on templates and designed for ease of localization.
- http://chiqchaq.sourceforge.net

CGI::Wiki
- A Perl toolkit for developing wikis.
- http://search.cpan.org/dist/CGI-Wiki/

CGI::pWiki
- Wiki Perl module published at CPAN.
- http://www.copyleft.de/pWiki/