How to Parse JSON in Python

Parsing a JSON String with json.loads()

Use json.loads() to parse a JSON string into Python data structures. The json module is part of the Python standard library — no install required.

import json

# Parse a JSON string
json_string = '{"name": "Alice", "age": 30, "active": True}'
# Note: JSON uses true/false/null — Python gets True/False/None
json_string = '{"name": "Alice", "age": 30, "active": true}'
data = json.loads(json_string)

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

# Parse a JSON array
json_array = '[1, 2, 3, "four", true, null]'
arr = json.loads(json_array)
print(arr[3])   # four
print(arr[5])   # None  (JSON null → Python None)

Reading JSON from a File with json.load()

import json

# Read a JSON file
with open("config.json", "r", encoding="utf-8") as f:
    config = json.load(f)  # load() reads from file object

print(config["database"]["host"])

# Read JSON from a URL response
import urllib.request

with urllib.request.urlopen("https://api.example.com/data") as response:
    data = json.load(response)  # response is file-like

# With requests library (recommended)
import requests

response = requests.get("https://api.example.com/data")
response.raise_for_status()
data = response.json()  # auto-parses JSON response

Serializing Python to JSON with json.dumps()

import json

data = {
    "name": "Alice",
    "age": 30,
    "roles": ["admin", "editor"],
    "active": True,
    "score": None
}

# Compact JSON string
json.dumps(data)
# '{"name": "Alice", "age": 30, "roles": ["admin", "editor"], ...}'

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

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

# Write JSON to a file
with open("output.json", "w", encoding="utf-8") as f:
    json.dump(data, f, indent=2)  # json.dump() writes to file

Error Handling — json.JSONDecodeError

import json

def safe_parse(json_string):
    try:
        return json.loads(json_string)
    except json.JSONDecodeError as e:
        print(f"JSON error: {e.msg}")
        print(f"  Line {e.lineno}, column {e.colno}")
        print(f"  Near: {e.doc[max(0,e.pos-20):e.pos+20]}")
        return None

# JSONDecodeError provides:
# e.msg    — error description
# e.lineno — line number of the error
# e.colno  — column number
# e.pos    — character position
# e.doc    — the original JSON string

result = safe_parse('{"name": "Alice",}')  # trailing comma
# JSON error: Expecting property name enclosed in double quotes
# Line 1, column 18

JSON ↔ Python Type Mapping

Parse JSON in Other Languages

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