I've been using jq for a handful of small personal projects over the last month or so. I was sceptical of its promise to be to JSON what sed is to flat text, because those are big shoes to fill. But now, looking back at where and how I've used it, jq really has come through. Definitely staying in my toolkit.

Ouah jq is pretty cool. REPL is more targeted to the occasional coder, or the advanced developer looking to quickly manipulate some JSON

jq is cool, but can it also be used to construct JSON? It's great for parsing, but OP's tool covers all the different aspects.

Yes, It can.

While we are there, if you want to manipulate JS not just JSON:

http://graspjs.com/