Purpose and Intended Audience
This page provides a history of the answers to questions asked on the legal-discuss@ mailing list,
and the scope of those answers. As each answer is as much dictated by Apache Software Foundation (ASF)
policy as any other interpretation, it is of most value to ASF projects.
Software License Criteria
The following criteria serve as guidelines for the answers on this page.
- The license must meet the Open Source Definition.
- The license must not place restrictions on the distribution of independent works that simply use or contain the covered work.
- The license must not place restrictions on the distribution of larger works, other than to require that the covered component still complies with the conditions of its license.
Asking Questions
Please submit questions to the Legal Affair Committee JIRA space.
For the purposes of being a dependency to an Apache product, which licenses are considered
to be similar in terms to the Apache License 2.0?
Works under the following licenses may be included within Apache products:
Many of these licenses have specific attribution terms that need to be adhered to, for example CC-A, often by adding
them to the NOTICE file. Ensure you are doing this when including these works. Note, this list is colloquially known
as the Category A list.
Which licenses may NOT be included within Apache products?
This list is colloquially known as the Category X list. Further discussion of disallowed licenses:
- BCL
- The Binary Code License falls far short of the Open Source Definition, thereby violating the first criterion for license approval.
- NPL
- The NPL is simply the Mozilla Public License plus
amendments that are specific to Netscape. Unfortunately, these
amendments allow "Netscape" (now part of Time Warner) to avoid the
reciprocity requirement that all other licensees must adhere to. This
disqualifies the license from meeting Open Source Definition #5 ("No
Discrimination Against Persons or Groups"). Therefore, the NPL is listed as an
excluded license.
- GNU GPL
- Discussion of Apache License v2.0 and GPL Compatibility merits a separate page.
- GNU LGPL
- The LGPL is ineligible primarily due to
the restrictions it places on larger works, violating the third
license criterion. Therefore, LGPL-licensed works must not be
included in Apache products.
- Special exceptions to the GNU GPL
- Some copyright holders have licensed their works under the GPL with
special exceptions. Although these exceptions may appear to be
addressing the restrictions disallowed by the ASF's first and second
license criteria, the exceptions may only apply to software not
"derived from or based on" the covered work. This references terms
defined in the GPL that include works that "use" or "contain" the
work.
- Field of use restrictions
- Some licenses restrict the uses to which software licensed under them may be be used.
An example is the Microsoft Limited Public License which limits the software or
derivatives to the Windows platform. Java licenses have often forbidden the use of
the software in particular environments (air traffic control, nuclear facilities etc).
Can Apache projects have external dependencies on Ruby licensed works?
A project written primarily and obviously in Ruby can have a dependency either on Matz's Ruby Interpreter (MRI),
or on any Gem which is licensed under the Ruby license.
Of course Gems written under other licenses (such as MIT) may also be OK, depending on the license.
Can Apache projects include Creative Commons Attribution-Share Alike works?
Unmodified media under the
Creative Commons Attribution-Share Alike 2.5 and
Creative Commons Attribution-Share Alike 3.0
licenses may be included in Apache products, subject to the licenses attribution clauses which may require
LICENSE/NOTICE/README changes. For any other type of CC-SA licensed work, please contact the Legal PMC.
How should so-called "Weak Copyleft" Licenses be handled?
Each license in this category requires some degree of reciprocity;
this may mean that additional action is warranted in order to
minimize the chance that a user of an Apache product will create a
derivative work of a reciprocally-licensed portion of an Apache
product without being aware of the applicable requirements.
Software under the following licenses may be included in binary form
within an Apache product if the inclusion is appropriately labeled:
By including only the object/binary form, there is less exposed
surface area of the third-party work from which a work might be
derived; this addresses the second guiding principle of this policy.
By attaching a prominent label to the distribution and requiring an
explicit action by the user to get the reciprocally-licensed source,
users are less likely to be unaware of restrictions significantly
different from those of the Apache License. Please include the
URL to the product's homepage in the prominent label.
For small amounts of source that is directly consumed by the ASF
product at runtime in source form, and for which that source is
unmodified and unlikely to be changed anyway (say, by virtue of being specified by a
standard), inclusion of appropriately labeled source is also
permitted. An example of this is the web-facesconfig_1_0.dtd, whose
inclusion is mandated by the JSR 127: JavaServer Faces specification.
This is colloquially known as the Category B list.
Can Apache products include works licensed under the JSON license?
The JSON Java library may be included. Please contact
legal-discuss@ for other products under this license.
Doug Lea's concurrent library is public domain, but contains some
Sun files which are not public domain. Can this be included in an Apache product?
Yes, treat it much as you currently would the Category B licenses above
- "it may be included in binary form within an Apache product if the inclusion
is appropriately labeled". If using the source, remove the files Sun licensed to Doug and
treat as Category A (or get it from
Harmony).
Can OSGi metadata be added to weak copyleft binaries - thus modifying the binary jar file?
Insertion of OSGi metadata into 'Category B' licensed jars is
permitted; even though that metadata becomes licensed under the 3rd
party license when it is put in the jar, assuming that a note that this has occurred is included in the
prominent labeling that the Category B language calls for.
Can Cobertura reports be included in Apache distributions?
It does not matter, unless the terms for that platform affect
the Apache product's licensing. For example, creating a product that
runs on Windows or Java, uses a web service such as Google Services or
Yahoo Search, or is a plugin for a product such as JBoss or JIRA is fine, whereas
creating a Linux kernel module is not fine because the Apache product
itself would have to be licensed under something other than the Apache License, version 2.0.
Note that this does not mean the platform code itself can be redistributed. That of course will
depend on the licensing of said code. Also, if you have any doubts as to whether the licensing
of the platform would affect the Apache code, we recommend that you check the legal-discuss@
archives to see if it has come up before, and if not email legal-discuss@ to find out.
Does the Yahoo! DomainKeys Patent License Agreement v1.2 raise any concerns?
Is
IP clearance required for library dependencies?
No.
IP clearance
is used to import code bases from outside Apache for future development here.
How should licenses that prevent modification be handled?
There are licenses that give broad rights for redistribution of
unmodified copies. Such licenses are not open source, but they
do satisfy the second and third guiding principles above.
Apache projects must not include material under such licenses in
version control or in released source packages. It is however acceptable
for a build process to automatically download such non-software materials
like fonts and standardized data and include them in the resulting
binaries. Such use makes it clear that these dependencies are not a part
of the open source code of the project.
Material under the following licenses may be used as described above: