JSON — Reading & Writing JSON Data — Free Python Tutorial

TL;DR: Learn JSON — Reading & Writing JSON Data in Python with a free, beginner-friendly tutorial, examples and practice for Indian students on Syllab.in.

JSON — Reading & Writing JSON Data in Python

JSON (JavaScript Object Notation) is the universal data exchange format for web APIs, configuration files, and data storage. Python's json module makes it trivial to convert between JSON strings and Python dicts/lists.

Two directions: serialisation (Python → JSON string) uses json.dumps(obj) or json.dump(obj, file); deserialisation (JSON string → Python) uses json.loads(string) or json.load(file).

Type mapping: Python dict ↔ JSON object, list ↔ array, str ↔ string, int/float ↔ number, True/False ↔ true/false, None ↔ null. Anything else (datetime, custom class) needs a custom encoder.

Formatting options: indent=4 for pretty-printing, sort_keys=True for consistent output, ensure_ascii=False to preserve Unicode characters like Indian scripts.

import json

# Python dict → JSON string
text = json.dumps(data, indent=4)

# JSON string → Python dict
data = json.loads(text)

# Write to file
with open("data.json", "w") as f:
    json.dump(data, f, indent=4)

# Read from file
with open("data.json") as f:
    data = json.load(f)

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