CPAN Module Distributions

Perl's License

Most CPAN modules are licensed under the same license as Perl. In their docu 

mentation they contain something like the following:

Copyright (c) YEAR, NAME.  All rights reserved.  This module is free software;

you can redistribute it and/or modify it under the same terms as Perl itself.

Perl's license is a bit unusual it is a hybrid license. A hybrid license is one that 

allows users to choose between more than one license. In this case, the user is 

offered the choice between the GPL and the Artistic License. The GPL is the GNU

General Public License created by the Free Software Foundation.

Perl's license is included in the Perl distribution in a file called README. You 

can view a copy of the GPL on the Web at http://www.gnu.org/copyleft/gpl.html.

The Artistic License was created for Perl and can be found on the Web at

http://www.perl.com/language/misc/Artistic.html.

Using Other Licenses

Using Perl's license for your module is generally a good idea. Since your users are 

already using Perl, you know that the license will be acceptable to them. When 

most modules use the same license, it makes life easier for users since they don't 

have to worry about whether using a module will put them in danger of legal 

troubles. In addition, module authors benefit since they can share code without 

needing to worry about incompatible

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 licenses. However, CPAN doesn't place any 

restrictions on the license you apply to your module. The only practical requirement 

is that the module must be freely distributable; otherwise CPAN itself would be 

violating your license by distributing your module among the CPAN mirrors!

If you choose to use a license other than Perl's, you should make sure that 

users will know about it. Consider putting a large warning at the top of your 

module documentation and README to get their attention. Better yet, consider 

just using Perl's license. It's the best thing for the Perl community.

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27. Licenses are incompatible when the terms of one license specify restrictions that are not 

allowed by the other.

28. Even the Free Software Foundation, usually a proponent of pure GPL usage, agrees:  We 

recommend you use [the Perl] license for any Perl 4 or Perl 5 package you write, to promote 

coherence and uniformity in Perl programming.  See http://www.gnu.org/philosophy/

license list.html for this quote and more.

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