json.dumps can handle nested data structures, too. More on reddit.com

Hmm minda sharing an anonymized version of the file? It is hard to follow. from what i read it seems like it is a list of dictionaries and you want to merge all the dictionaries right? So from functools import reduce j = json.load(...) combined = reduce(lambda x,y: {**x, **y}, j) Explanation: Reduce takes running pairs and runs the lambda which combines dictionaries. So essentially it takes a running sum of the dictionaries to combine them. Most people like looping, but this is readable to me. For loop: ... combined = j[0] for d in j[1:]: combined = {**combined, **d} Note: in py3.9+ you can do x|y instead of {**x,**y} More on reddit.com

let obj = arr1.map((id,ix)=> ({id, name: arr2[ix] } )); For all such doubts, post on r/javascript This subreddit is for ReactJS related discussions. More on reddit.com

I would think: First pass: identify all the keys (which will become the column names). So for the example JSON, you'd identify that the columns are ["name", "age", "dob"]. Second pass: You can now build up each row from each record. You'd set each column value in the CSV by simply checking if the JSON object has that key (eg, does the second row have an "age" key? Nope. So it gets an empty string in that column). I've never used the libraries you've considered, so can't speak to their capabilities, but you should be able to find a JSON library that simply creates an internal representation that combines dictionaries and lists (and thus do not need to provide an class to populate from the JSON data). So you'd do something like: JsonArray people = json.getArray("People"); for(JsonObject person : people) { List keys = person.keys(); for(String key : keys) { JsonValue value = person.get(key); // Use value.toString() to store in the CSV -- now everything's a string } } Of course, this is making some presumptions about the JSON library, so you'd have to do some research and maybe tweak a bit. This is based on a rough Java conversion of a Scala JSON library I used before (namely the Play Framework's JSON library ). It should be possible to find a Java library with the same capabilities. The CSV writing should be more straightforward from my above description. You'd loop over all column names and check if there's a key equal to that column name. If so, give the CSV writer value.toString(). if not, give it an empty string. More on reddit.com