What are the differences between
Open-source licenses require different degrees of
reciprocity from a licensee. In this list, each
license category includes the same basic terms as
the previous category. I'll leave out the corporate
vanity licenses, since they aren't typically adopted
by new projects.
No reciprocity: new BSD, MIT. These licenses simply
grant permission to copy the software, and disclaim
Patent reciprocity: Apache. In order to redistribute
software under this license, a licensee must offer a
license to any of the licensee's patents that apply.
Partial copyright reciprocity: Mozilla Public License,
Lesser GPL. A licensee must provide source code for
changes to the original work, but can still add code
that is somehow kept distinct from the original, and
keep it proprietary.
Broad copyright reciprocity: GPL (all versions). If a
licensee distributes a modified version that
constitutes a "derivative work" for purposes of
copyright law, that derivative work must be available
in source code form.
Protections from complex legal schemes: GPLv3. Some
patent trolling schemes and code signing systems have
the effect of working around the reciprocity
requirements of the GPL. This later version of the
license closes some loopholes.
SaaS reciprocity: Affero GPL. The only commonly used
license that requires a licensee to redistribute source
even if the code is not actually redistributed.
Offering AGPL-licensed software for use over a network
also triggers the requirement to redistribute source.
Syndicated 2013-05-21 02:51:50 from Don Marti