Comment by natefinch

There's a big difference between reverse engineering (i.e. intentionally writing software that behaves identically to another piece of software), and writing your own code to solve your own problem that may superficially contain small portions of the similar logic as some other project. Copyrighted code has to be sufficiently creative and unique to qualify, otherwise after the first person wrote code to parse json from a web request, no one else would be able to do the same thing.