Working with JSON in Python: Complete Developer Guide

The Python json Module

Python ships with a built-in json module. No third-party library is required to parse or generate JSON in Python 3.

Core Functions:

• json.loads(string) — Parse a JSON string into a Python dict or list.
• json.dumps(obj) — Serialize a Python object to a JSON string.
• json.load(file) — Parse JSON directly from an open file object.
• json.dump(obj, file) — Write JSON directly to an open file object.

Pretty Printing JSON in Python

Pass indent=2 or indent=4 to json.dumps() for human-readable output. Add sort_keys=True for alphabetically ordered keys.

Validating JSON in Python

Wrap json.loads() in a try/except block to catch json.JSONDecodeError syntax errors:

import json

# Parse JSON string
payload = '{"name": "Alice", "score": 99, "active": true}'
data = json.loads(payload)
print(data["name"])  # Alice

# Pretty print JSON
pretty = json.dumps(data, indent=2, sort_keys=True)
print(pretty)

# Validate JSON safely
def is_valid_json(text: str) -> bool:
    try:
        json.loads(text)
        return True
    except json.JSONDecodeError:
        return False

# Read/Write JSON files
with open("data.json", "r") as f:
    obj = json.load(f)

with open("output.json", "w") as f:
    json.dump(obj, f, indent=2)