An open-source license is a copyright license for computer software that makes the source code available under terms that allow for modification and royalty-free redistribution. One popular (and sometimes considered normative) set of open source licenses are those approved by the Open Source Initiative based on their Open Source Definition.

OSI Approved Licenses (http://www.opensource.org/licenses/)

Software in the public domain (that is, with no copyright license at all), meets those criteria as long as all source code is made available, and is therefore recognized by the OSI and entitled to use their service mark. In addition, OSI has approved the following licenses as of 2003:

• Academic Free License
• Apache Software License
• Apple Public Source License
• Artistic License
• Common Public License
• Eiffel Forum License
• BSD License
• GNU General Public License (GPL)
• GNU Lesser General Public License (LGPL)
• Historical Permission Notice and Disclaimer
• IBM Public License
• Intel Open Source License
• Jabber Open Source License
• MIT License
• MITRE Collaborative Virtual Workspace License (CVW License)
• Motosoto License
• Mozilla Public License 1.0 (MPL)
• Mozilla Public License 1.1 (MPL 1.1)
• NetHack General Public License
• Nokia Open Source License
• Open Software License
• Open Group Test Suite License
• Python license
• Python Software Foundation License
• Q Public License (QPL)
• Ricoh Source Code Public License
• Sleepycat License
• Sun Industry Standards Source License (SISSL)
• Sun Public License (SPL)
• Vovida Software License v. 1.0
• W3C License
• X.Net License
• zlib-libpng license
• Zope Public License

Non-OSI open source licenses

Licenses which are source-available but not OSI-Certified include:

• Solaris
• PGP
• SpamPal (an anti-spam program with a license which prohibits spamming as a means of selling the program or derivative works. Since that restricts a field of endeavor, it's not open source according to the Open Source Definition.)

Comparisons

It should be noted that the Free Software Foundation has related but distinct criteria for evaluating whether or not a license qualifies a program as free software. See Free software license.

Likewise, the Debian project has its own criteria, the Debian Free Software Guidelines, which in many ways was a precursor to the Open Source Definition.

See also

• Free Software Foundation
• Open Source Initiative
• Open source
• Open source movement
• Public domain
• Software license

External links

• The Open Source Initiative (http://www.opensource.org/)

• Microsoft comments on Open Source Licenses (http://www.microsoft.com/resources/sharedsource/Articles/LicensingOverview.mspx)
• Open Source Licensing (http://books.slashdot.org/article.pl?sid=04/09/21/0239245) a review and discussion of Lawrence Rosen's book Open Source Licensing: Software Freedom and Intellectual Property Law (ISBN 0131487876) on slashdot