I am making a web app and would like to use CKEditor5 with its non-commercial license (GNU General Public License Version 2 or later). I've read through this, but am still not sure I understand my obligations.
My frontend is a React app which is being compiled alongside a CKEditor5 build, so I'm pretty sure I'm obligated to make all of that source code publicly available. But what about my backend code that the frontend interacts with through a REST API, can I keep it closed source? I can't find any clear explanation of what the boundary is of GPL license infectiousness.
This question seems similar where the answer states
all code in your application must have a GPL-compatible open-source license and the project as a whole (including the binaries) must be distributed under the GPL license., but what defines the boundaries of the "project", can I consider two pieces of code communicating over a REST API to be separate projects?