Latest version 2.0 DFSG compatible Yes | Published January 2004 FSF approved Yes | |
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Author Publisher Apache Software Foundation | ||
The Apache License (ASL) is a permissive free software license written by the Apache Software Foundation (ASF). The Apache License requires preservation of the copyright notice and disclaimer. Like other free software licenses, the license allows the user of the software the freedom to use the software for any purpose, to distribute it, to modify it, and to distribute modified versions of the software, under the terms of the license, without concern for royalties. This makes ASL a FRAND-RF license. The ASF and its projects release the software they produce under the Apache License and many non-ASF projects are also using the ASL.
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A free software license is a notice that grants the recipient extensive rights to modify and redistribute that software. These actions are usually prohibited by copyright law, but the rights-holder (usually the author) of a piece of software can remove these restrictions by accompanying the software with a software license which grants the recipient these rights. Software using such a license is free software (or free and open source software) as conferred by the copyright holder. Free software licenses are applied to software in source code as also binary object code form, as the copyright law recognizes both forms.
Version 1.1
The Apache License 1.1 was approved by the ASF in 2000: The primary change from the 1.0 license is in the 'advertising clause' (section 3 of the 1.0 license); derived products are no longer required to include attribution in their advertising materials, but only in their documentation.
Version 2.0
The ASF adopted the Apache License 2.0 in January 2004. The stated goals of the license included making the license easier for non-ASF projects to use, improving compatibility with GPL-based software, allowing the license to be included by reference instead of listed in every file, clarifying the license on contributions, and requiring a patent license on contributions that necessarily infringe a contributor's own patents.
Licensing conditions
The Apache License is permissive in that it does not require a derivative work of the software, or modifications to the original, to be distributed using the same license (unlike copyleft licenses – see comparison). It still requires application of the same license to all unmodified parts and, in every licensed file, any original copyright, patent, trademark, and attribution notices in redistributed code must be preserved (excluding notices that do not pertain to any part of the derivative works); and, in every licensed file changed, a notification must be added stating that changes have been made to that file.
If a NOTICE text file is included as part of the distribution of the original work, then derivative works must include a readable copy of these notices within a NOTICE text file distributed as part of the derivative works, within the source form or documentation, or within a display generated by the derivative works (wherever such third-party notices normally appear).
The contents of the NOTICE file do not modify the license, as they are for informational purposes only, and adding more attribution notices as addenda to the NOTICE text is permissible, provided that these notices cannot be understood as modifying the license. Modifications may have appropriate copyright notices, and may provide different license terms for the modifications.
Unless explicitly stated otherwise, any contributions submitted by a licensee to a licensor will be under the terms of the license without any terms and conditions, but this does not preclude any separate agreements with the licensor regarding these contributions.
GPL compatibility
The Apache Software Foundation and the Free Software Foundation agree that the Apache License 2.0 is a free software license, compatible with version 3 of the GNU General Public License (GPL), meaning that code under GPL version 3 and Apache License 2.0 can be combined, as long as the resulting software is licensed under the GPL version 3.
The Free Software Foundation considers all versions of the Apache License to be incompatible with the previous GPL versions 1 and 2 and, furthermore, considers Apache License versions before v2.0 incompatible with GPLv3. Because of version 2.0's patent license requirements, the Free Software Foundation recommends it over other non-copyleft licenses, specifically recommending it either for small programs or for developers who wish to use a permissive license for other reasons.
Reception and adoption
In October 2012, 8,708 projects located at SourceForge.net were available under the terms of the Apache License. In a blog post from May 2008, Google mentioned that over 25% of the nearly 100,000 projects then hosted on Google Code were using the Apache License, including the Android operating system.
As of 2015, according to Black Duck Software and GitHub, the Apache license is the third most popular license in the FOSS domain after MIT license and GPLv2.