Python JSON Tutorial — Parse, Create, and Convert JSON

Python's built-in json module makes working with JSON straightforward. This guide covers every real-world scenario you'll encounter.

Parse JSON strings

import json

# json.loads() — string to Python object
json_string = '{"name": "Alice", "age": 28, "active": true}'
data = json.loads(json_string)

print(data['name'])   # Alice
print(data['age'])    # 28
print(type(data))     # <class 'dict'>

Create JSON strings

import json

data = {
    'name': 'Alice',
    'age': 28,
    'tags': ['developer', 'python'],
    'address': {'city': 'Paris'}
}

# Compact
json.dumps(data)

# Pretty-printed
json.dumps(data, indent=2)

# Sorted keys
json.dumps(data, indent=2, sort_keys=True)

# ASCII-safe (escape non-ASCII)
json.dumps({'emoji': '😀'}, ensure_ascii=True)
# '{"emoji": "\ud83d\ude00"}'

# Keep Unicode
json.dumps({'emoji': '😀'}, ensure_ascii=False)
# '{"emoji": "😀"}'

Read and write JSON files

import json

# Read JSON file
with open('data.json', 'r', encoding='utf-8') as f:
    data = json.load(f)

# Write JSON file
with open('output.json', 'w', encoding='utf-8') as f:
    json.dump(data, f, indent=2, ensure_ascii=False)

Handle JSON from HTTP APIs

import requests  # pip install requests

response = requests.get('https://api.example.com/users')
response.raise_for_status()  # raises on 4xx/5xx
data = response.json()  # parses JSON automatically
print(data[0]['name'])

Handle dates in JSON

from datetime import datetime, date
import json

# Dates aren't JSON-serializable by default
class DateEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, (datetime, date)):
            return obj.isoformat()
        return super().default(obj)

data = {'created': datetime.now(), 'date': date.today()}
json_str = json.dumps(data, cls=DateEncoder)
# '{"created": "2023-11-14T22:13:20.123456", "date": "2023-11-14"}'

Pretty-print JSON in terminal

# One-liner to format JSON from command line
echo '{"name":"Alice","age":28}' | python3 -m json.tool

# Format a file
python3 -m json.tool data.json

JSON type mapping

JSON	Python
object {}	dict
array []	list
string	str
number (int)	int
number (float)	float
true / false	True / False
null	None