Open Software License

kc@example.com (kc kim) — Sun, 17 Mar 2019 01:31:20 +0900

What Is a License?

License in a broad sense
- A permit or certificate.
- Permission granted by an administrative authority to qualify someone to perform a specific activity.
License in software
- A right to use software, or a document stating that use is permitted.

Free Software License

Freedom, not price; it is not about whether software is free of charge.
Meaning of freedom
- Freedom to run the program for any purpose.
- Freedom to study how the program works and change it to fit one’s needs.
- Freedom to copy and distribute the program to help others.
- Freedom to improve the program and return those improvements for the benefit of the whole community.

Free Software Foundation

Founded by Richard Stallman on October 4, 1985.
An organization that promotes free copying, distribution, and improvement of software.
Main activities
- Maintaining free software philosophy.
- Protecting copyrighted free software.
http://www.fsf.org

License Classification

GPL-compatible free software licenses
- GPL, LGPL, Apache 2.0, and so on.
GPL-incompatible free software licenses
- Apache 1.0, BSD, MPL, and so on.
NonFree software licenses
- Code Project License, JSON, and so on.

License Types

GPL(The GNU General Public License)

A license created by the Free Software Foundation. Richard Stallman created it for software distributed as part of the GNU Project.
It is one of the best-known open source licenses and has relatively strict obligations compared with other open source licenses.
GPL programs can be used for any purpose and in any form, but if a used or modified program is distributed, it must be released under the same license. A notice such as “This product(SW) includes ○○○(name of GPL SW used), which is distributed under the GPL license” must be included in a manual or equivalent medium, and the full GPL text must be attached.
Computer programs can be used for any purpose, except actions restricted by law.
Executable copies of computer programs must always be sold with the program source code or the source code must be distributed for free.
The source code of modified source programs can be changed according to purpose.
Modified computer programs must also disclose and distribute the source code.
Modified programs must also adopt the exact same license, meaning the GPL license must be applied.

Item	Yes/No
Copyright protection	Yes
Can be used in commercial software	Yes
Obligation to provide bug patches and feature extensions	Yes
Explicit patent rights can be exercised	No
Can be used in proprietary software(closed-source software)	No
License propagation	Yes

AGPL(Affero General Public License)

A license based on GPL. Versions 1 and 2 were developed by Affero, and version 3 was developed by the Free Software Foundation.
This license was created to solve the problem where users cannot obtain source code if a developer uses modified source code only on a server and does not distribute the program.
It contains a clause requiring that, when a program is run on a server and communicates with other users, users must be able to download the source code of the running program.

LGPL(The Lesser GNU General Public License)

LGPL is a license created by the Free Software Foundation so that some libraries can be used with a somewhat relaxed source-code disclosure requirement compared with GPL. It relaxes GPL restrictions.
If open source libraries that provide the same functionality as commercial libraries were given a strict license like GPL, developers would avoid using them because they would have to disclose source code. LGPL was created to prevent that and encourage open source use.
For a library under LGPL, the original program’s source code does not need to be disclosed; only the source code of the open source used must be disclosed.
It was originally named Library GPL because it was intended to apply only to limited libraries, but to avoid the misunderstanding that it applied to every library, it was changed to Lesser GPL in version 2.1.
When dynamically linking a library with the LGPL license, the obligation to disclose source code disappears.
If an LGPL-licensed library is modified, the modified library source must be disclosed.
The GNU Foundation currently promotes it.

Item	Yes/No
Copyright protection	Yes
Can be used in commercial software	Yes
Obligation to provide bug patches and feature extensions	Yes
Explicit patent rights can be exercised	No
Can be used in proprietary software(closed-source software)	Yes
License propagation	Yes

The BSD(Berkeley Software Distribution) License

BSD is an open software license distributed by the University of California, Berkeley, and is one of the representative open source licenses that does not require source code disclosure.
The BSD license has a broad scope of permission because projects distributed under the BSD license were funded by the U.S. government, meaning by public institutions and U.S. taxpayers.
In other words, because the cost of the software was paid in advance by U.S. citizens’ taxes, people were permitted to use or create software in whatever way they wanted, emphasizing public benefit.
Therefore, even if new programs are developed using BSD-licensed source code, the new program’s source code does not need to be disclosed, and it can be sold under a license other than BSD.

Item	Yes/No
Copyright protection	Yes
Can be used in commercial software	Yes
Obligation to provide bug patches and feature extensions	No
Explicit patent rights can be exercised	No
Can be used in proprietary software(closed-source software)	Yes
License propagation	No

MPL(Mozilla Public License)

The Mozilla Foundation decided to open the Netscape source code as MS Explorer’s market share rose, and developed a new license because of GPL restrictions and BSD uncertainty.
It permits free use, copying, distribution, and modification of programs.
MPL was developed to disclose the source code of the Netscape browser and defines the scope of source code that must be disclosed more clearly.
In GPL, the scope of source code that must be disclosed, including linked software, is vaguely defined. In MPL, regardless of linking, there is no obligation to disclose source code written in new files that were not part of the original source code.
Therefore, MPL software itself must be disclosed no matter what, but new files that did not exist in the original source code do not need to be disclosed.

The Apache License, Version 2.0

A license created by the Apache Software Foundation.
It applies to all software from the Apache Foundation, including the Apache web server. It is similar to the BSD license and does not impose obligations such as source-code disclosure.
However, it explicitly includes a clause that the “Apache” trademark must not be infringed, and it includes patent-related content.
If Apache-licensed source code is modified and distributed, Apache License Version 2.0 must be included, and it must be stated that the software was made by the Apache Foundation.
Anyone can create derivative programs, transfer copyrights, and distribute the software.
There is no obligation to disclose source code.

Item	Yes/No
Copyright protection	Yes
Can be used in commercial software	Yes
Obligation to provide bug patches and feature extensions	No
Explicit patent rights can be exercised	Yes
Can be used in proprietary software(closed-source software)	Yes
License propagation	No

The MIT License

MIT is a license developed by the Massachusetts Institute of Technology in the United States to help its software engineering students.
It only requires that license and copyright notices be preserved. It was written based on the BSD license, and because it does not require modified source code to be distributed as open source, it is popular with users who want to avoid strict licenses such as GPL.

Item	Yes/No
Copyright protection	Yes
Can be used in commercial software	Yes
Obligation to provide bug patches and feature extensions	No
Explicit patent rights can be exercised	No
Can be used in proprietary software(closed-source software)	Yes
License propagation	No

CPOL(The Code Project Open License)

Item	Yes/No
Copyright protection	Yes
Can be used in commercial software	Yes
Obligation to provide bug patches and feature extensions	No
Explicit patent rights can be exercised	Yes
Can be used in proprietary software(closed-source software)	Yes
License propagation	No

CDDL(The Common Development and Distribution License)

Item	Yes/No
Copyright protection	Yes
Can be used in commercial software	Yes
Obligation to provide bug patches and feature extensions	Yes
Explicit patent rights can be exercised	Yes
Can be used in proprietary software(closed-source software)	Yes
License propagation	No

Ms-PL(The Microsoft Public License)

Item	Yes/No
Copyright protection	Yes
Can be used in commercial software	Yes
Obligation to provide bug patches and feature extensions	No
Explicit patent rights can be exercised	Yes
Can be used in proprietary software(closed-source software)	Yes
License propagation	No

MPL 1.1(The Mozilla Public License 1.1)

Item	Yes/No
Copyright protection	Yes
Can be used in commercial software	Yes
Obligation to provide bug patches and feature extensions	Yes
Explicit patent rights can be exercised	Yes
Can be used in proprietary software(closed-source software)	Yes
License propagation	No

CPL(The Common Public License Version 1.0)

Item	Yes/No
Copyright protection	Yes
Can be used in commercial software	Yes
Obligation to provide bug patches and feature extensions	Yes
Explicit patent rights can be exercised	Yes
Can be used in proprietary software(closed-source software)	Yes
License propagation	No

The Eclipse Public License 1.0

Item	Yes/No
Copyright protection	Yes
Can be used in commercial software	Yes
Obligation to provide bug patches and feature extensions	Yes
Explicit patent rights can be exercised	Yes
Can be used in proprietary software(closed-source software)	Yes
License propagation	No

The Creative Commons Attribution-ShareAlike 2.5 License

Item	Yes/No
Copyright protection	Yes
Can be used in commercial software	Yes
Obligation to provide bug patches and feature extensions	No
Explicit patent rights can be exercised	No
Can be used in proprietary software(closed-source software)	No
License propagation	Yes

The zlib/libpng License

Item	Yes/No
Copyright protection	Yes
Can be used in commercial software	Yes
Obligation to provide bug patches and feature extensions	No
Explicit patent rights can be exercised	No
Can be used in proprietary software(closed-source software)	Yes
License propagation	No

Contribution to the Public Community(Not a License)

Item	Yes/No
Copyright protection	No
Can be used in commercial software	Yes
Obligation to provide bug patches and feature extensions	No
Explicit patent rights can be exercised	No
Can be used in proprietary software(closed-source software)	Yes
License propagation	No

devkuma – License

Open Software License

What Is a License?

Free Software License

Free Software Foundation

License Classification

License Types

GPL(The GNU General Public License)

AGPL(Affero General Public License)

LGPL(The Lesser GNU General Public License)

The BSD(Berkeley Software Distribution) License

MPL(Mozilla Public License)

The Apache License, Version 2.0

The MIT License

CPOL(The Code Project Open License)

CDDL(The Common Development and Distribution License)

Ms-PL(The Microsoft Public License)

MPL 1.1(The Mozilla Public License 1.1)

CPL(The Common Public License Version 1.0)

The Eclipse Public License 1.0

The Creative Commons Attribution-ShareAlike 2.5 License

The zlib/libpng License

Contribution to the Public Community(Not a License)

Sources