WEKA is licensed under the GNU General Public license (GPL 2.0 for Weka 3.6) and (GPL 3.0 for Weka > 3.7.5). Any derivative work obtained under this license must be licensed under the GPL if this derivative work is distributed to a third party.
For commercial projects that require the ability to distribute WEKA code as part of a program that cannot be distributed under the GPL, it may be possible to purchase an appropriate license from the copyright holders listed in the corresponding Java classes.
Projects that only require a small subset of algorithms or filters can use the tiny-weka library as basis. This library consists of core classes of WEKA and is released under the liberal MIT license. Only additional classes need then be licensed. A ready-to-use maven template is available as well.
The copyright for most WEKA code is owned by the University of Waikato. For information on licenses for this code please contact WaikatoLink, the commercialization unit of the University of Waikato, by sending email to weka-enquiries at waikatolink.co.nz.