An open-source license is a copyright license for computer software that follows the principles of the open source movement. More formally, a license is considered open-source when it has approved by the Open Source Initiative, with the criteria being the Open Source Definition. Software in the public domain (that is, with no copyright license at all), meets those criteria as long as all source code is made available, and is therefore recognized by the OSI and entitled to use their service mark.

In addition, OSI has approved the following licenses as of 2003:

It should be noted that the Free Software Foundation has different criteria for evaluating whether or not a license qualifies a program as free software. See Free software license.

See also: open source, open source movement, Open Source Initiative, Free Software Foundation, Public domain