The problem here I am facing is, when the object is loaded a lot of memory is used and the memory used is not freed fully, so the difference in this accumulates gradually. So I was looking for formats which can be processed without keeping the entire text in memory.
For the first one: look in specific json lib forums, ask there, check open issues, open issue. (all those stackoverflow questions/answers are really confusers, not helpers).
For the second one: so it's text, i'd transfer text then. It's too much text? Process it in chunks. Your final format is json? Encapsulate your text as json at the last final step.