I just stumbled on the draft of the OSI license proliferation committee report. This drafts list nine licenses as widely used and thus candidates which should be considered first by those needing a license for their open source software. As it just lists the licenses without comments I made up the following list combining it with the FSF comments on these licenses. This is of course the biased view of the FSF but useful to me, as I use the GNU General public license Version 2 (GPL 2) for my work. The ordering of the list is as in the report draft. The list reflects the situation as it was on 2006-09-24 with updates pertaining to the release of GPL v3.
The licenses compatible with GPL 2 are: New BSD license, LGPL, MIT X11 license. In addition the Apache license is compatible with GPL3.
- Apache License, 2.0
With release of GPL 3 the text was modified to: "This is a free software license, compatible with version 3 of the GPL. Please note that this license is not compatible with GPL version 2, because it has some requirements that are not in the older version. These include certain patent termination and indemnification provisions."
The original wording was: "This is a free software license but it is incompatible with the GPL. The Apache License is incompatible with the GPL because it has a specific requirement that is not in the GPL: it has certain patent termination cases that the GPL does not require. (We don't think those patent termination cases are inherently a bad idea, but nonetheless they are incompatible with the GNU GPL.)"
- New BSD license
- On the FSF page this license figures as "Modified BSD license"
This is the original BSD license, modified by removal of the advertising clause. It is a simple, permissive non-copyleft free software license, compatible with the GNU GPL.
If you want a simple, permissive non-copyleft free software license, the modified BSD license is a reasonable choice. However, it is risky to recommend use of ``the BSD license'', because confusion could easily occur and lead to use of the flawed original BSD license. To avoid this risk, you can suggest the X11 license instead. The X11 license and the revised BSD license are more or less equivalent.
This license is sometimes referred to as the 3-clause BSD license.
- GNU General Public License (GPL version 2)
-
With release of GPL 3 the text was modified to: "This is the previous version of the GNU GPL: a free software license, and a copyleft license. We recommend the latest version for most software. Please note that GPLv2 is, by itself, not compatible with GPLv3. However, most software released under GPLv2 allows you to use the terms of later versions of the GPL as well. When this is the case, you can use the code under GPLv3 to make the desired combination."
The original wording was: "This is a free software license, and a copyleft license. We recommend it for most software packages."
- GNU Library or "Lesser" General Public License (LGPL version 2)
-
With release of LGPL 3 the text was modified to: "This is the previous version of the LGPL: a free software license, but not a strong copyleft license, because it permits linking with non-free modules. It is compatible with GPLv2 and GPLv3. We generally recommend the latest version of the LGPL, for special circumstances only."
The original wording was: "This is a free software license, but not a strong copyleft license, because it permits linking with non-free modules. It is compatible with the GNU GPL. We recommend it for special circumstances only. Between version 2 and 2.1, the GNU LGPL was renamed from the GNU Library General Public License to the GNU Lesser General Public License to better reflect its actual purpose. Namely, it is not just for libraries, and the GNU GPL is sometimes more appropriate for libraries.
- MIT license
- On the FSF page this license figures as "X11 license".
This is a simple, permissive non-copyleft free software license, compatible with the GNU GPL. Older versions of XFree86 used the same license, and some of the current variants of XFree86 also do. Later versions of XFree86 are distributed under the XFree86 1.1 license (which is GPL-incompatible).
This license is sometimes called the "MIT license", but that term is misleading, since MIT has used many licenses for software.
- Mozilla Public License 1.1 (MPL)
This is a free software license which is not a strong copyleft; unlike the X11 license, it has some complex restrictions that make it incompatible with the GNU GPL. That is, a module covered by the GPL and a module covered by the MPL cannot legally be linked together. We urge you not to use the MPL for this reason.
However, MPL 1.1 has a provision (section 13) that allows a program (or parts of it) to offer a choice of another license as well. If part of a program allows the GNU GPL as an alternate choice, or any other GPL-compatible license as an alternate choice, that part of the program has a GPL-compatible license.
- Common Development and Distribution License
This is a free software license which is not a strong copyleft; it has some complex restrictions that make it incompatible with the GNU GPL. It requires that all attribution notices be maintained, while the GPL only requires certain types of notices. Also, it terminates in retaliation for certain aggressive uses of patents. So, a module covered by the GPL and a module covered by the CDDL cannot legally be linked together. We urge you not to use the CDDL for this reason.
Also unfortunate in the CDDL is its use of the term "intellectual property"
- Common Public License
This is a free software license but it is incompatible with the GPL.
The Common Public License is incompatible with the GPL because it has various specific requirements that are not in the GPL. For example, it requires certain patent licenses be given that the GPL does not require. (We don't think those patent license requirements are inherently a bad idea, but nonetheless they are incompatible with the GNU GPL.)
- Eclipse Public License
The Eclipse Public License is similar to the Common Public License, and our comments on the CPL apply equally to the EPL. The only change is that the EPL removes the broader patent retaliation language regarding patent infringement suits specifically against Contributors to the EPL'd program.
