We're talking about JSON parsing here: a solved problem.
Solved for your use case(s), you mean. You're saying that you cannot imagine a reasonable circumstance under which off-the-shelf solutions wouldn't fit your needs? (Hint: if you write code for a living, this very scenario is why you have a job.)
Welcome to Developers 2.0, where writing a program means duct-taping together 500+ 'micro libraries' (each of which has a dependency tree like fucking crab grass) with maybe a dozen lines of bootstrap code.
Solved for your use case(s), you mean. You're saying that you cannot imagine a reasonable circumstance under which off-the-shelf solutions wouldn't fit your needs? (Hint: if you write code for a living, this very scenario is why you have a job.)