Open-Core

Open-core is the approach of providing a “core” offering using FOSS code, but then offer additional other versions of the software built on this open core which makes use of non-FOSS code. This is commonly used as a business model by projects, as they make use of the adoption and marketing advantages of open source for the core offering while allowing the author to retain some kind of competitive market advantage.

There’s a vast range in the practical implementation & impact of open core. It can be done in a transparent manner, where user rights are made clear, different offerings are clearly provided under separate distribution means, and where marketing does not conflate the FOSS and non-FOSS offerings. Unfortunately though, it’s often used in ways that have issues to user transparency, by conflating the offerings & not being clear on their differences, while treating the open core as a demo or up-sell tool.

In an ideal scenario, the core FOSS offering can still provide value under the useful rights which FOSS provides, and would therefore be open to community forking where needed or desired. That said, open core projects are more prone to further issues like source poisoning, and sometimes their core is more limited than expected.