JSON in Python — Parse, Format & Generate

Python's built-in json module makes it straightforward to parse, generate, and manipulate JSON data. No third-party packages are required for most tasks.

Parse a JSON string

Use json.loads() to parse a JSON string into a Python dict or list. The 's' stands for string.

import json

json_string = '{"name": "Alice", "age": 30, "active": true}'
data = json.loads(json_string)

print(data["name"])   # Alice
print(data["age"])    # 30
print(type(data))     # <class 'dict'>

Read a JSON file

Use json.load() (without 's') to parse a JSON file directly from a file object.

import json

with open("data.json", "r", encoding="utf-8") as f:
    data = json.load(f)

print(data)

Serialize Python objects to JSON

Use json.dumps() to convert a Python dict or list to a JSON string. Use indent for pretty-printing.

import json

data = {"name": "Alice", "scores": [95, 87, 92], "active": True}

# Compact
compact = json.dumps(data)
print(compact)
# {"name": "Alice", "scores": [95, 87, 92], "active": true}

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

Write a JSON file

Use json.dump() to write Python data directly to a file.

import json

data = {"name": "Alice", "active": True}

with open("output.json", "w", encoding="utf-8") as f:
    json.dump(data, f, indent=2)

Handle JSON errors

Catch json.JSONDecodeError when parsing untrusted input.

import json

bad_json = '{"name": "Alice", missing_quote}'

try:
    data = json.loads(bad_json)
except json.JSONDecodeError as e:
    print(f"Parse error: {e.msg} at line {e.lineno}, col {e.colno}")

JSON Formatter →JSON to Python Dataclass →JSON to YAML →JSON to CSV →

Frequently Asked Questions

How do I parse JSON in Python?▾

Use json.loads() to parse a JSON string into a Python dict or list. For files, use json.load() with an open file object.

What is the difference between json.loads() and json.load()?▾

json.loads() parses a JSON string (the 's' stands for string). json.load() reads and parses from a file object directly.

How do I pretty-print JSON in Python?▾

Pass indent=2 (or any number) to json.dumps(): json.dumps(data, indent=2). This adds newlines and indentation.

How do I handle JSON parse errors in Python?▾

Wrap json.loads() in a try/except block and catch json.JSONDecodeError. It provides the error message, line number, and column number.

Can Python serialize custom objects to JSON?▾

Not directly. Use default= parameter to provide a custom encoder function, or subclass json.JSONEncoder and override the default() method.

JSON in Other Languages

JSON in JavaScript →JSON in TypeScript →JSON in Go →JSON in Java →JSON in PHP →JSON in Ruby →JSON in C# →JSON in Rust →JSON in Kotlin →JSON in Swift →JSON in Dart →JSON in Scala →JSON in Next.js →JSON in Express →JSON in FastAPI →JSON in Django →JSON in Terraform →

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