Large json

It stops with an error?

If it's too big for memory, the best approach would be to just search for the tokens that you want. You'd probably want to check both the current and last bit of data together, in case the information you want spans multiple ones:

var last = "";
res.on('data',function(data) {
  var s = last+data;
  if (s.indexOf(...)) ...;
  last = data;
});

Potentially if you just want some of the data, you could bracket-count until you get to the right part?