multilicense

Multilicense is a licensing approach in which a work is made available under more than one license, giving users the option to choose the terms under which they may use, modify, and distribute it. The licensor retains ownership while offering multiple license terms.

Most multilicense schemes are dual licensing or multi-license arrangements. The included licenses may be permissive (such as MIT, BSD, or Apache) or copyleft (such as GPL or LGPL). Under a multilicense model, a user may satisfy obligations by complying with one of the licenses, or, in many cases, may opt to purchase a commercial license to avoid copyleft requirements.

Rationale: Multilicense aims to maximize adoption by serving different communities—open-source users who prefer copyleft or permissive terms, and commercial users who seek explicit warranties, support, or the ability to avoid copyleft obligations. It can also help with license compatibility and revenue generation.

Practical considerations include license compatibility when combining modules, continued compliance with the chosen license, and the potential for obligations to apply to derivative works and distributions. Organizations using multilicense software should review terms carefully and ensure they meet any disclosure, attribution, or royalty requirements.

Examples include projects that offer GPL or commercial licenses, LGPL with a commercial option, or MIT/BSD/Apache alongside paid licenses. Qt has historically offered open-source terms alongside commercial terms, and MySQL has used a dual-licensing model.