Json is a format which looks like plain text. I guess you know what you are asking. If you need to convert a file containing Json text to a readable format, you need to convert that to an Object and implement toString() method(assuming converting to Java object) to print or write to another file in a much readabe format. You can use any Json API for this, for example Jackson JSON API.

ObjectMapper obj = new ObjectMapper();
T t=obj.readValue(File src, Class<T> valueType) 

t.toString();  //this must have been implemented

You can use pre tag to display formatted json.

const json = {
  id: "1",
  employee_name: "Tiger Nixon",
  employee_salary: "320800",
  employee_age: "61",
  profile_image: ""
};
document.getElementById("app").innerHTML = JSON.stringify(json, (key, value) => (value || ''), 4).replace(/"([^"]+)":/g, '$1:');

	<div><pre id="app"></pre></div>

I am not too sure why you want to format your Json response, it should be your service client which should do the formatting if required. You am look at the Json Pretty Printer/Beautifier Library For .Net, which takes Json string as input and return a formatted Json string.

The json module in python already implements some basic pretty printing with the indent parameter:

import json
parsed = json.loads(your_json)
print(json.dumps(parsed, indent=2, sort_keys=True))