The Weka Workbench
The Weka Workbench is among the most popular machine learning frameworks in the world. It was developed by computer scientists at the University of Waikato and is used by entry-level data scientists and large multinationals alike, in applications from business intelligence to robotics. It contains a collection of data pre-processing tools and machine learning algorithms wrapped up in an easy-to-use graphical interface.
Weka is a great example of commercial open source software. By choosing a commercial open source model, WaikatoLink has made the software freely available to non-commercial users while generating revenue from issuing paid licenses to commercial users. This revenue helps to support research and continues to improve the platform.
Find out more about Weka here: https://www.cs.waikato.ac.nz/ml/weka/