Yes - it's free, but ...
SOFA Statistics is completely free and you can use it without restriction on as many machines as you like. The application is released under the open source AGPL3 licence.
The main ways you can support the project are by:
If there are particular features you need that are not currently available, we can always discuss the possibility of a commission payment to have them developed, or to have them developed more quickly.
University academics might be able to participate using grants from its Fund for Innovation and Excellence in Teaching
The International Rice Research Institute provided early funding for development of a customised CAST e-book with biological examples that later became the Biometric e-book in CAST.
The Rockefeller Foundation contributed towards development of the two African CAST e-books that were originally targeted at agriculture students in sub-Saharan Africa.
Both the UK Met Office and the UK Department for International Development helped to fund a series of e-books for use in courses run by the University of Reading to teach basic statistics to climatologists in Africa.
The CAST material about design of industrial experiments was developed with funding from Nestlé.
The World Food Programme funded development of the first chapter of the Official Statistics e-book about Data Presentation.
Andrew W. Mellon Foundation
Tertiary Education Commission
Supported by $1.5 million in funding from the Tertiary Education Commission, The Open Polytechnic project team selected an open source eLearning system, Moodle, and made improvements to it for widespread release. Open Polytechnic receives international award
We could explicitly mention that we are willing to discuss bounties etc with interested parties e.g. $5,000 for the addition of major functionality - perhaps that required by a business integrator making a killing off our product .