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Mercurial as a whole is licensed under GPL version 2 '''only'''. This means it is completely free for most uses including redistribution. Mercurial as a whole is licensed under [http://selenic.com/hg/file/tip/COPYING GPL version 2] '''only'''. This means it is completely free for most uses including redistribution.
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You are free to copy files marked "GPL version 2 or later" on their own for use with GPLv3 software. See the distributed COPYING file for the license on all other files. You are free to copy files marked "GPL version 2 or later" on their own for use with GPLv3 software. See the distributed [http://selenic.com/hg/file/tip/COPYING COPYING] file for the license on all other files.

What is Mercurial's license?

Mercurial as a whole is licensed under [http://selenic.com/hg/file/tip/COPYING GPL version 2] only. This means it is completely free for most uses including redistribution.

Can I get a commercial license?

Mercurial is Free Software. To use it for your commercial development, simply download it, install it, and enjoy. If you are interested in commercial support, see ["Support"].

When does the license affect me?

If you do not distribute software that works with Mercurial, you have no license obligations.

If you distribute software that does not modify Mercurial's source code and only calls Mercurial's command line interface, you have no license obligations.

If you intend to distribute software that includes changes to Mercurial's source code or directly calls Mercurial's internals, your work may be considered a 'derived work' according to copyright law, and you will need to license your work under the GPLv2 and make its source code available.

Is the Mercurial license compatible with...

If you are building a project that combines multiple works, you must ensure that their licenses are compatible if you want to be able to distribute it.

The GPLv2 license is not compatible with several newer open source licenses, including:

  • GPL version 3
  • The Eclipse EPL
  • The Sun CDDL
  • The Apache License

This means, for instance, that you cannot write a plugin for Eclipse that directly calls Mercurial's internals, as the resulting work would need to be simultaneously licensed under the EPL and the GPLv2. The FSF has a longer list of [http://www.gnu.org/philosophy/license-list.html#GPLIncompatibleLicenses incompatible licenses].

An example of a compatible license is the MIT license or the "3 clause" BSD license. When combining projects with these licenses with Mercurial, the result has a GPLv2 license.

Why isn't Mercurial GPLv3-compatible?

Mercurial predates the existence of GPLv3 and it was not clear at the time that the GPLv3 would be an improvement so we chose to be GPLv2-only. Whether the GPLv3 is an improvement remains unclear; arguably the resulting license-compatibility problems alone have made it a net failure.

Will you relicense/dual-license/sublicense Mercurial?

No. We are happy with our current choice of license and there is currently no sufficiently compelling reason to consider relicensing.

Also, as there is not a single copyright holder for Mercurial, relicensing would be a very time-consuming multi-month process with no certainty of success.

Why do some parts of Mercurial's source have different license clauses?

Mercurial includes code contributed and borrowed from many sources. Some of these use the "GPL version 2 or later" clause. But because most code (including most of the Mercurial core) is GPLv2 only, the package as a whole is effectively GPLv2 only, as it's the only license that fits the requirements of all files.

You are free to copy files marked "GPL version 2 or later" on their own for use with GPLv3 software. See the distributed [http://selenic.com/hg/file/tip/COPYING COPYING] file for the license on all other files.

License (last edited 2019-04-05 16:02:01 by AugieFackler)