JSON Formatter, Minifier, and Validator in Python — Code Examples

JSON parsing and serialisation is built into every major language. Here is how to parse a JSON string, format (pretty-print) JSON, and handle common edge cases in each language.

Python's json module has json.loads() for parsing and json.dumps() for serialization. Use indent for pretty-printing.

import json

# Parse JSON string → dict
data = json.loads('{"name": "Alice", "age": 30}')
print(data["name"])  # Alice

# Serialize dict → JSON string
json_str = json.dumps(data)
print(json_str)  # {"name": "Alice", "age": 30}

# Pretty-print
pretty = json.dumps(data, indent=2)
print(pretty)
# {
#   "name": "Alice",
#   "age": 30
# }

# Sort keys alphabetically
sorted_json = json.dumps(data, sort_keys=True, indent=2)

# Read/write JSON files
with open("data.json", "w") as f:
    json.dump(data, f, indent=2)

with open("data.json") as f:
    loaded = json.load(f)

# Custom serializer for non-JSON types (e.g. datetime)
from datetime import datetime

class DateEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, datetime):
            return obj.isoformat()
        return super().default(obj)

print(json.dumps({"ts": datetime.now()}, cls=DateEncoder))

• json.loads() raises json.JSONDecodeError on invalid JSON (a subclass of ValueError).
• Python dicts are ordered (Python 3.7+) — json.dumps() preserves insertion order.
• Use ensure_ascii=False in json.dumps() to output Unicode characters directly instead of \uXXXX escapes.

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