Kitware has as well. The vast majority of the work done is open. There are, however, customer-specific builds for some things, but typically only "special sauce

Kitware has as well. The vast majority of the work done is open. There are, however, customer-specific builds for some things, but typically only "special sauce" stuff is specific to those builds and is much closer to "customer purchased development of a specific plugin" than anything like open core. FD: Kitware employee