TheApple Public Source License (APSL) is theopen-source andfree software license under whichApple'sDarwinoperating system was released in 2000. A free and open-source software license was voluntarily adopted to further involve the community from which much of Darwin originated.

The first version of the Apple Public Source License was approved by theOpen Source Initiative (OSI).^[5] Version 2.0, released July 29, 2003, is also approved as a free software license by theFree Software Foundation (FSF) which finds it acceptable for developers to work on projects that are already covered by this license. However, the FSF recommends that developers should not release new projects under this license, because the partialcopyleft is not compatible with theGNU General Public License and allows linking with files released entirely asproprietary software.^[4]

The license does require that if any derivatives of the original source are released externally, their source should be made available; the Free Software Foundation compares this requirement to a similar one in its ownGNU Affero General Public License.^[4]

Many software releases from Apple have now beenrelicensed under the more liberalApache License, such as theBonjourZeroconf stack. However, most OS component source code remains under APSL.

• Software using the Apple Public Source License (category)

• Text of the Apple Public Source License
• Free Software Foundation's opinion on the license

• Free and open-source software licenses
• Permissive software licenses
• Apple Inc.

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• Use mdy dates from June 2013