JSON Formatter — Developer Code Samples

Format JSON data programmatically using built-in language features. All examples produce the same output as the online JSON Formatter tool. No external dependencies required — Python's json module and JavaScript's JSON object handle everything.

Try the interactive version online: Open JSON Formatter Tool →

Parameters

Parameter	Type	Required	Description
json_string	str	Yes	Raw JSON string to format or parse
indent	int	No	Number of spaces for indentation (default: 2)
sort_keys	bool	No	Sort object keys alphabetically

Returns: Formatted JSON string with proper indentation, or minified single-line JSON

Code Examples

import json

# Format (pretty-print) JSON
data = '{"name":"Alice","age":30,"city":"NYC"}'
parsed = json.loads(data)
formatted = json.dumps(parsed, indent=2, sort_keys=True)
print(formatted)
# Output:
# {
#   "age": 30,
#   "city": "NYC",
#   "name": "Alice"
# }

# Minify JSON
minified = json.dumps(parsed, separators=(',', ':'))
print(minified)
# Output: {"age":30,"city":"NYC","name":"Alice"}

# Validate JSON
def is_valid_json(s):
    try:
        json.loads(s)
        return True
    except json.JSONDecodeError:
        return False

# Format a JSON file
def format_json_file(input_path, output_path, indent=2):
    with open(input_path) as f:
        data = json.load(f)
    with open(output_path, 'w') as f:
        json.dump(data, f, indent=indent, sort_keys=True)
    print(f"Formatted JSON written to {output_path}")

// Format (pretty-print) JSON
const data = '{"name":"Alice","age":30,"city":"NYC"}';
const parsed = JSON.parse(data);
const formatted = JSON.stringify(parsed, null, 2);
console.log(formatted);
// Output:
// {
//   "name": "Alice",
//   "age": 30,
//   "city": "NYC"
// }

// Minify JSON
const minified = JSON.stringify(parsed);
console.log(minified);
// Output: {"name":"Alice","age":30,"city":"NYC"}

// Validate JSON
function isValidJSON(str) {
  try {
    JSON.parse(str);
    return true;
  } catch (e) {
    return false;
  }
}

// Format with sorted keys (Node.js)
function sortedJSON(obj, indent = 2) {
  return JSON.stringify(
    Object.fromEntries(Object.entries(obj).sort()),
    null,
    indent
  );
}

# Format JSON with jq
echo '{"name":"Alice","age":30}' | jq .

# Minify JSON with jq
echo '{"name":"Alice","age":30}' | jq -c .

# Format JSON file
cat data.json | jq . > formatted.json

# With Python (no dependencies)
python3 -m json.tool data.json

# Validate and format in one step
python3 -c "import json,sys; print(json.dumps(json.load(sys.stdin), indent=2))" < data.json

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