Multi-licensing

Multi-licensing is the practice of distributing software under two or more different sets of terms and conditions. This may mean multiple different software licenses or sets of licenses. Prefixes may be used to indicate the number of licenses used, e.g. dual-licensed for software licensed under two different licenses.

When software is multi-licensed, recipients can choose the terms under which they want to use or distribute the software. The distributor may or may not apply a fee to either option. The two usual motivations for multi-licensing are license compatibility and market segregation based business models.

Business models

Multi-licensing is commonly done to support free software business models in a commercial environment. In this scenario, one option is a proprietary software license, which allows the possibility of creating proprietary applications derived from it, while the other license is a copyleft free software/open-source license, thus requiring any derived work to be released under the same license. The copyright holder of the software then typically provides the free version of the software at little or no cost, and profits by selling proprietary licenses to commercial operations looking to incorporate the software into their own business. This model can be compared to shareware.