I think the best way could be to have a JSON with comments file type for the lenient parsing if the core JSON type to allow it. A global option as you suggest will basically force anyone to disable strict mode if they have just have just 1+ files that rely on the expanded syntax, which IMHO turns A option useless. It's not like usually a dev's choice, really, what files they have to deal with. So with a global option you might as well just leave things as they are right now (which I think wouldn't be the worst thing to do, actually)