BSD license

From Wikinfo

See also BSD license: a view from the GFDL corpus

The BSD license is a permissive free software license, originally from the BSD operating system. It allows everyone to use, share, and modify the software that it covers. Modified versions of the software may be free or non-free. The BSD license does not contain the extra legalese of copyleft; it is perfectly okay to share the software without including the source code.

Like almost every software license, the BSD license also contains a warranty disclaimer.

There are now several BSD-like licenses. This article distinguishes the licenses that follow the spirit of the original BSD license, from the licenses that have extra terms and are not BSD-like.

BSD-like licenses

We now enumerate through the BSD-like licenses. These licenses are normally okay within projects that wish to continue the original BSD licensing policy.

The original BSD license

Here is a BSD license copied from the OpenBSD Copyright Policy:

   Copyright (c) 1982, 1986, 1990, 1991, 1993
        The Regents of the University of California.  All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met:
   1. Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
   2. Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
   3. All advertising materials mentioning features or use of this software
      must display the following acknowledgement:
        This product includes software developed by the University of
        California, Berkeley and its contributors.
   4. Neither the name of the University nor the names of its contributors
      may be used to endorse or promote products derived from this software
      without specific prior written permission.

   THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS AND
   ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   SUCH DAMAGE.

In the original BSD license, the copyright holder is "The Regents of the University of California". This license was used for the 4.3BSD-Net/1, 4.4BSD-Lite, and 4.4BSD-Lite 2 releases of the BSD source code from the University of California, Berkeley.

At 1999, the Regents deleted item 3 (the obnoxious BSD advertising clause) from the license for BSD code that they own. Other copyright holders using the BSD license had changed the advertising clause to refer to them instead of the University, potentially requiring advertisers to include hundreds or thousands of sentences in their advertisements. Though this is only a problem for advertising, and only when the advertising "mentioning features or use of this software", it is still awkward to include a permissive free license.

Unfortunately, some other copyright holders still use some form the advertising clause in their BSD licenses. If you recommend the BSD license to someone, remember to tell them not to use the advertising clause! It helps to point them to the OSI template of the BSDL-3, which does not include the advertising clause.

The 3-clause BSD license (BSDL-3)

When an author decides to use the BSD license, they need to change the license to refer to themselves instead of the University. The Open Source Initiative (OSI) has a template of the new BSD license which anyone can use:

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
Neither the name of the <ORGANIZATION> nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

We call this license the 3-clause BSD license, the BSDL-3, and also the new BSD license or revised BSD license. OSI has changed "REGENTS AND CONTRIBUTORS" to "COPYRIGHT HOLDERS AND CONTRIBUTORS" in the warranty disclaimer.

Some other authors rewrite the last clause and the warranty disclaimer as follows:

The name of the author may not be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE AUTHOR "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

This version is more appropriate if the author is only a single person and not an organization with many contributors.

The 2-clause BSD license (BSDL-2)

The BSDL-2 license is simply the BSDL-3 license with the removal of the clause about misusing the author's name. This license is popular in FreeBSD development. Here is an example taken from libelf from FreeBSD:

   Copyright (c) 2006 Joseph Koshy
   All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met:
   1. Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
   2. Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.

   THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS AND
   ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   SUCH DAMAGE.

The BSDL-2 and BSDL-3 licenses are effectively the same. Because nothing ever gave permission to misuse the author's name, it is not important to write a clause prohibiting such misuse into the license.

The MIT/X license

The MIT/X license is commonly found within parts of the X Window System. We call it the MIT/X license, because X also contains software under other licenses, and MIT has also distributed software under other licenses. Here is a copy from OSI:

Copyright (c) <year> <copyright holders>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

This license is effectively the same as the BSDL-3 and BSDL-2 licenses, but has become a very popular alternative, both within and outside *BSD projects. The MIT/X license has never included the obnoxious BSD advertising clause, and has never required different authors to rewrite the license to refer to themselves. The MIT/X license is also shorter than most of the BSD licenses.

The ISC license

The ISC license is yet shorter than the MIT/X license. We call it the "ISC license" because the Internet Software Consortium uses it for their BIND software.

The ISC license is used in new code added to OpenBSD. Here is copy of the template from /usr/src/share/misc/license.template on OpenBSD systems:

   Copyright (c) CCYY YOUR NAME HERE <user@your.dom.ain>

   Permission to use, copy, modify, and distribute this software for any
   purpose with or without fee is hereby granted, provided that the above
   copyright notice and this permission notice appear in all copies.

   THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

This license is effectively the same as the BSDL-3, BSDL-2 and MIT/X licenses. The shorter language is made possible through the Berne Convention.

The MirOS license

The MirOS license is more generic then the above licenses; it does not use the word "software", so one may apply the license to other works as well as to software. Here is a copy from the MirOS license template:

   Copyright (c) year, year, year, ...
        First M. Last <user@host.domain>

   Provided that these terms and disclaimer and all copyright notices
   are retained or reproduced in an accompanying document, permission
   is granted to deal in this work without restriction, including un-
   limited rights to use, publicly perform, distribute, sell, modify,
   merge, give away, or sublicence.

   This work is provided "AS IS" and WITHOUT WARRANTY of any kind, to
   the utmost extent permitted by applicable law, neither express nor
   implied; without malicious intent or gross negligence. In no event
   may a licensor, author or contributor be held liable for indirect,
   direct, other damage, loss, or other issues arising in any way out
   of dealing in the work, even if advised of the possibility of such
   damage or existence of a defect, except proven that it results out
   of said person's immediate fault when using the work as intended.

When applied to software, the above version of the MirOS license is effectively the same as the BSDL-3, BSDL-2, MIT/X and ISC licenses. There are also variants of the MirOS license with the obnoxious BSD advertising clause.

The Apache License 1.1

This copy is from the Apache Foundation:

   The Apache Software License, Version 1.1

   Copyright (c) 2000 The Apache Software Foundation.  All rights
   reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met:

   1. Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.

   2. Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in
      the documentation and/or other materials provided with the
      distribution.

   3. The end-user documentation included with the redistribution,
      if any, must include the following acknowledgment:
         "This product includes software developed by the
          Apache Software Foundation (http://www.apache.org/)."
      Alternately, this acknowledgment may appear in the software itself,
      if and wherever such third-party acknowledgments normally appear.

   4. The names "Apache" and "Apache Software Foundation" must
      not be used to endorse or promote products derived from this
      software without prior written permission. For written
      permission, please contact apache@apache.org.

   5. Products derived from this software may not be called "Apache",
      nor may "Apache" appear in their name, without prior written
      permission of the Apache Software Foundation.

   THIS SOFTWARE IS PROVIDED ``AS IS AND ANY EXPRESSED OR IMPLIED
   WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
   ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   SUCH DAMAGE.
   ====================================================================

   This software consists of voluntary contributions made by many
   individuals on behalf of the Apache Software Foundation.  For more
   information on the Apache Software Foundation, please see
   <http://www.apache.org/>.

   Portions of this software are based upon public domain software
   originally written at the National Center for Supercomputing Applications,
   University of Illinois, Urbana-Champaign.

The Apache License 1.1 differs from a typical BSD-like in two ways:

clause 3 requires an acknowledgment in the documentation.
clause 5 restricts the use of the "Apache" trademark.

However, you automatically satisfy clause 3, including the acknowledgment, when you preserve the copyright and permission notice (which happens to contain the acknowledgment). Meanwhile, clause 5 sets the rules for the Apache trademark, and has no affect on the BSD-like copyright license. Thus OpenBSD does include Apache 1.x under the Apache License 1.1.

The current Apache License 2.0 is not BSD-like for obvious reasons.

Licenses that are not BSD-like

Now we consider licenses that have additional terms that were not part of the original BSD license. Those licenses are not BSD-like. There are some obvious cases: any proprietary software license is not BSD-like; any free software license that includes a copyleft is not BSD-like; the GNU General Public License is not BSD-like.

So we focus upon licenses that seem BSD-like but are not so. A common case is that someone takes one of the above licenses, adds some additional terms, then claim that the license is BSD-like though it is not. We have bolded the terms that are not from BSD.

The Sleepycat or Oracle Berkeley DB license

This copy is from Oracle:

   Copyright (c) 1990-2006
        Oracle Corporation.  All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met:
   1. Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
   2. Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
   3. Redistributions in any form must be accompanied by information on
      how to obtain complete source code for the DB software and any
      accompanying software that uses the DB software.  The source code
      must either be included in the distribution or be available for no
      more than the cost of distribution plus a nominal fee, and must be
      freely redistributable under reasonable conditions.  For an
      executable file, complete source code means the source code for all
      modules it contains.  It does not include source code for modules or
      files that typically accompany the major components of the operating
      system on which the executable file runs.

   THIS SOFTWARE IS PROVIDED BY ORACLE CORPORATION ``AS IS AND ANY EXPRESS
   OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR
   NON-INFRINGEMENT, ARE DISCLAIMED.  IN NO EVENT SHALL ORACLE CORPORATION
   BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
   THE POSSIBILITY OF SUCH DAMAGE.

Berkeley DB has its origins in BSD. However, when Sleepycat (now owned by Oracle) developed the newer versions of Berkeley DB, they added this clause so that they could also sell commercial licenses. The clause requires you to provide source code in some cases. It is less than a copyleft, because the source code might still contain other conditions.

Though the Sleepycat/Oracle Berkeley DB license is a free software license, it is not a BSD-like license, even though the other parts of the license seem BSD-like. FreeBSD and NetBSD and OpenBSD continue to include Berkeley DB 1.85, an older version with no Sleepycat/Oracle code.

The Sendmail License

The SSendmail License is not a BSD-like license. Section 1 contains additional terms vaguely similar to those in the Sleepycat/Oracle Berkeley DB license.

This is why OpenBSD includes sendmail in /usr/src/gnu/usr.sbin/sendmail; the /usr/src/gnu directory is for software that has extra license terms.

The XFree86 License 1.1

This copy is from XFree86:

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

1. Redistributions of source code must retain the above copyright notice, this list of conditions, and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution, and in the same place and form as other copyright, license and disclaimer information.

3. The end-user documentation included with the redistribution, if any, must include the following acknowledgment: "This product includes software developed by The XFree86 Project, Inc (http://www.xfree86.org/) and its contributors", in the same place and form as other third-party acknowledgments. Alternately, this acknowledgment may appear in the software itself, in the same form and location as other such third-party acknowledgments.

4. Except as contained in this notice, the name of The XFree86 Project, Inc shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization from The XFree86 Project, Inc.

THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE XFREE86 PROJECT, INC OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

The XFree86 License 1.1 is almost a BSD-like license. At first, clause 3 may appear to be the obnoxious BSD advertising clause, but is not. Clause 3 attaches no conditions to advertising.

Instead, it requires an acknowledgment in the software or documentation. Simply preserving the copyright and permission notice, as the BSD license requires, may not satisfy clause 3. Instead, any time you add another third-party acknowledgment to XFree86, you must also add the sentence acknowledging XFree86. Many users may never add another third-party acknowledgment when modifying XFree86, so clause 3 may never apply to them.

Though the XFree86 License 1.1 is a free software license, it is not a BSD-like license because clause 3 is an additional term never found in a BSD license. For this reason, the OpenBSD project does not accept code under the XFree86 License 1.1. (Many GNU/Linux distributions also rejected this license as it applies to XFree86, because they claimed that clause 3 was incompatible with the GNU Free Documentation License.)

This article is in the public domain

Instead of choosing one of the licenses for this article about the BSD license, this article is in the public domain and has no copyright. The text of the licenses themselves is also in the public domain.

Because there is no copyright holder, no one provides a warranty for this article.