Apache License

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Software Licenses > Open Source > Licenses > Apache

Apache License

The Apache License (previously known as the "Apache Software License") is a software licensed authored by the Apache Software Foundation ("ASF"). The license is used for all software produced by the ASF including the popular Apache Web Server software, but there are also at least 1,000 non-ASF projects which are also available under the Apache License.

The Apache License is quite a permissive license, and is not a copyleft license: it requires preservation of a copyright notice and a disclaimer, but allows use and distribution of the source code in both FLOSS and proprietary software.

There have been several revisions of the Apache License:

Apache Software License 1.0
Apache Software License 1.1 which was approved in 2000. The principle difference between 1.1 and 1.0, is in the license's advertising clause: whereas the 1.0 license required that derived products contain an attribution in their advertising material, the 1.1 license only requires attribution in their documentation.
Apache License 2.0 was approved by the ASF in early 2004, and its goals included making the license easier to apply, and easier for non-ASF projects to use. Additionally, this revision of the license aimed to require "a patent license on contributions that necessarily infringe a contributor's own patents". Furthermore, an attempt was made to make the license GPL compatible, although opinions differ on whether this was achieved or not:
- The Free Software Foundation considers all versions of the Apache License to be incompatible with the GPL Version 2. The argument is that patent termination clauses in the Apache License are the source of incompatibility.
- The Apache Software Foundation'd position is more complex: see their web site statement on Apache License v2.0 and GPL Compatibility for more information.
- Early drafts of the GPL Version 3 include patent retaliation clauses intended to make the licenses compatible.