Python JSON Formatter & Pretty Printer
Format and validate JSON for your Python projects. Paste your JSON below to instantly format it, then use the Python code examples to parse it in your application. All processing happens in your browser — your data never leaves your device.
How to format JSON in Python
Python's built-in json module handles JSON formatting with json.dumps(). To pretty print JSON: import json; formatted = json.dumps(data, indent=2, sort_keys=True). To read a JSON file: with open('data.json') as f: data = json.load(f). To write formatted JSON: with open('output.json', 'w') as f: json.dump(data, f, indent=2). The indent parameter controls spacing (2 or 4 spaces are standard), and sort_keys alphabetizes object keys for consistent output.
Common Python JSON errors and how to fix them
json.decoder.JSONDecodeError is the most common error when parsing JSON in Python. Common causes: trailing commas (invalid in JSON but valid in Python dicts), single quotes instead of double quotes, unquoted keys, comments in JSON, and NaN/Infinity values. Use this formatter to validate your JSON before calling json.loads(). If you're converting Python dicts to JSON, remember that Python True/False/None become true/false/null in JSON — json.dumps() handles this automatically.
Why use an online JSON formatter for Python development
When debugging API responses, inspecting configuration files, or validating webhook payloads, an online formatter is faster than writing a script. Paste the raw JSON, verify it's valid, format it for readability, then copy it into your Python code. This tool is especially useful when working with requests library responses (response.json()), FastAPI/Flask request bodies, or AWS Lambda event payloads. Since DevBolt processes everything client-side, it's safe to paste production API responses containing tokens or credentials.
Frequently Asked Questions
How do I pretty print JSON in Python?
Use json.dumps(data, indent=2) to pretty print JSON in Python. For a JSON string, first parse it with json.loads(json_string), then format it with json.dumps(parsed, indent=2, sort_keys=True). The indent parameter sets the number of spaces for indentation.
How do I fix JSONDecodeError in Python?
JSONDecodeError usually means the JSON is malformed. Common fixes: replace single quotes with double quotes, remove trailing commas, remove comments, ensure keys are quoted strings, and replace Python None/True/False with null/true/false. Use this formatter to validate your JSON and pinpoint the exact error location.
Can I use this formatter for Python dict output?
Yes. If you have a Python dict printed with print(), note that Python uses single quotes and None/True/False, which are not valid JSON. Convert it first with json.dumps(your_dict) in Python, then paste the output here to format it.
Related Format Tools
Code Minifier & Beautifier
Minify and beautify JavaScript, CSS, and HTML code instantly
YAML Formatter
Validate, format, beautify, and minify YAML documents instantly
SVG Optimizer
Optimize SVGs by removing metadata, comments, editor data, and unnecessary attributes
Markdown Preview
Write and preview Markdown with live rendering