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The term Open core or commercial open-source software refers to a business model involving the monetization of free and open-source software. This model primarily involves offering a "core" or feature limited version of a software product as free and open-source software, while offering "commercial" versions or add-ons as proprietary software, or offering other services for the open source version in a similar manner.
The concept of open core software has proved to be controversial, as many developers do not consider the business model to be true open source software. Despite this, open core models are used by a large number of open source software companies.
- MySQL (Support and licensing)
- Rapid7, with its Metasploit Pro and Metasploit Express products which are based on the open source Metasploit core framework.
It has been suggested by Bradley M. Kuhn that Canonical Ltd., maintainers of Ubuntu are preparing to go open core, but have not done so, according to the Canonical's contributor agreement and their Project Harmony which aimed "to assist organisations which use contribution agreements by providing standardised variable templates with clear and concise explanations...."
Assignment with protections against open core
Some open core models use copyright assignment, but it should be pointed out that some open source projects require assignment of copyright for the sole purpose of defending that copyright, with the promise of retaining (only) open source licensing. For example, by prosecuting modification and binary release of GPLed software without release of the modified source code.
Organisations which see open core as a danger include clauses in their assignment to prohibit open core licensing. One example is Free Software Foundation Europe's (FSFE) Fiduciary Licence Agreement (used by KDE). In this agreement, developers assign copyright to FSFE, but FSFE promises to use a free software licence when distributing the software:
FSFE shall only exercise the granted rights and licences in accordance with the principles of Free Software as defined by the Free Software Foundations. FSFE guarantees to use the rights and licences transferred in strict accordance with the regulations imposed by Free Software licences, including, but not limited to, the GNU General Public Licence (GPL) or the GNU Lesser General Public Licence (LGPL) respectively. In the event FSFE violates the principles of Free Software, all granted rights and licences shall automatically return to the Beneficiary and the licences granted hereunder shall be terminated and expire.
- Bradley M. Kuhn (2009-10-16). "“Open Core” Is the New Shareware".
- Simon Phipps (2010-06-29). "Open Core Is Bad For You". ComputerWorldUK.
- Brian Prentice (2010-03-31). "Open-Core: The Emperor’s New Clothes". Gartner.
- "Open Core Debate: The Battle for a Business Model". Linux Insider. Retrieved 28 March 2013.
- "Canonical, Ltd. Finally On Record: Seeking Open Core - Bradley M. Kuhn ( Brad ) ( bkuhn )". Ebb.org. Retrieved 2012-04-02.
- Amanda Brock (2010-06-24). "Project Harmony looks to improve contribution agreements".
- "FSFE welcomes KDE's adoption of the Fiduciary Licence Agreement (FLA)". 2008-08-22.
- "Fiduciary Licence Agreement (Version 1.2)". Retrieved 2010-12-31.
- "6.1 Copyright Papers". Retrieved 2011-01-03.
- "Licensing FAQ". Retrieved 2011-01-03.