duallicensing

Dual licensing is a licensing arrangement in which the rights holder offers the same work under two or more licenses, allowing recipients to choose which terms to follow. In software, this commonly combines an open-source license with a separate commercial license. The open-source option requires compliance with its terms (such as copyleft obligations or attribution), while the commercial option may permit proprietary use and provide different terms, including fees, warranties, or support.

This approach lets developers reach open-source communities while creating a revenue stream or broader business flexibility. It allows commercial users to adopt the work without triggering copyleft requirements, or to obtain services and warranties not available under the open-source license. It is especially common for projects seeking broad distribution alongside monetization, or for organizations that want to control downstream use in proprietary products.

Legal and practical considerations include ensuring license compatibility and avoiding conflicts between the two terms, as well as managing compliance across users. Licensors must draft harmonized terms so that distributions under one license do not violate obligations of the other. Potential drawbacks include user confusion and the overhead of administering two licensing tracks.

Notable examples include Qt, which has offered both a GPL/LGPL-based route and a commercial license, and certain database projects that historically provided a commercial license alongside a GPL-derived license.