JSONDecodeError: Extra Data

Why This Happens

json.loads() expects a single JSON document. Newline-delimited JSON (NDJSON) has multiple objects on separate lines and must be parsed line by line.

The Problem

import json
raw = '{"a": 1}\n{"b": 2}'
data = json.loads(raw)

The Fix

import json
raw = '{"a": 1}\n{"b": 2}'
data = [json.loads(line) for line in raw.strip().split('\n')]

Step-by-Step Fix

1. 1

   Parse line by line

   Split by newlines and parse each line.

2. 2

   Wrap in array

   Join objects with commas and wrap in brackets.

3. 3

   Check the source

   Some APIs return NDJSON requiring line-by-line parsing.