JavaScript JSON Console Utility

I need a small Javascript -based console program that focuses on one thing: taking JSON data in, performing defined transformations, and returning clean, reliable JSON out.

Core actions I expect

• Apply the transformation rules I will supply (re-keying objects, filtering arrays, basic calculations, or any other logic we define together)
• Write the processed JSON to a new file

If you like working with pure JavaScript, know your way around and can deliver clean, testable code quickly, let’s talk.
Basic quote will be accepted.