Dual Licensing in Open Source

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You can have your cake and eat it too, and share it as well. That's what dual licensing is in a nutshell. Most of the successful Open Source companies have one thing in common - their licensing pattern. If you're a developer, then "dual licensing" is something that allows you to earn from your work and at the same time give back to the community.

The Dual Licensing model
Simply put, Dual Licensing is the practice of distributing identical software under two different sets of terms and conditions, with or without monetary benefits. When a software is dual licensed, its recipient is free to choose either of the two sets of 'terms of use' offered by the software company.

Besides license compatibility and market segregation, the biggest motivation for software developers to offer their software under the “Dual Licensing” model is to make money by monetizing their intellectual property. After all the developer also has the right to earn money.

The software developer may offer the same software at different prices (or even free)-to a single user for personal use, and to a group of users or corporates. However, the software continues to remain open, ie the source is still available to the end user. Thus the dual licensing model helps both free software community as well as the commercial software licensee.

The Dual Licensing policy sustains innovation as well as growth. The open availability of code lets the software to be improved by those who have the right to change it under an Open Source license. The proceeds from commercial licensing help fund additional development.


Success stories
Several companies have made a fortune by adopting dual licenses. The best known example is MySQL AB-the most popular Open Source data base. MySQL has two license options: commercial license and a modified GPL license, which allows the licensee to distribute MySQL code under GPL along with other Free and Open Source Software licenses.

Trolltech is another company that provides a cross platform toolkit called Qt, which is used to develop GUIs for applications. This company makes use of Dual Licensing for its product. Its GPL version is used by KDE, while its commercial version is used by Skype, Google Earth, etc. Trolltech's commercial license allows its users to develop and distribute their applications under standard commercial terms. Its Open Source versions are available under the terms of GPL.

Concerns and restrictions
So is dual license truly a great license to work with? Do you really get to keep your code and sell it too? Or do you end up getting flak? Well it depends on the who and the what-Who is offering the product and what that product is.

As is the case with all Open Source software projects, the only person (or group of persons) who can decide on the kind of license to use, are creators of the software. A successful software does get a lot of contributor inputs from its GPL'd licensee, while it gets to earn money from corporates to strengthen its financial base. Also, once a software has been given an open license, changing it for future versions to a different or a closed license is very difficult if not impossible.


The premise of Dual Licensing is community contribution to the product's code base and a continuous cycle of revisions and improvisations. Managing the contributions from the GPL'd branch as well as from the commercial branch can be a tricky business and may involve not just community but legal issues as well.

Many startups love the idea of Dual Licensing and jump on to it without giving much of a thought or considering the legal implications. The success of a few big names can drive smaller entities into thinking of potential publicity as well quick money-which though not impossible, is not so easy to achieve.

A startup may also find a potential investor or acquirer for his company who loves the software product, but who may or may not like the idea of investing in a company that uses dual licenses.

Does it really work?
Dual Licensing is not a new practice. Software companies have traditionally used versions of their products as shareware or freeware for the customers, and have done well for themselves commercially. Note that most shareware or freeware are not Open Source products. However, companies like Red Hat have successfully sponsored communities while continuing with their commercial line of Open Source products.

The biggest non monetary benefit for the company in using a Dual License software, is the continuous product development cycle it brings along, So yes, it does work if the business involved has a product that is strong and both licenses are well etched out.

The license has served the companies using it very well not only financially but also in terms of popularity as can be judged from the popularity of MySQL and Qt.



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