How to convert JSON to CSV in Python

Python scripts that process API responses, database exports, or data pipeline outputs frequently need to write CSV files. The quickhelp.dev JSON-to-CSV REST API lets you convert data without writing the CSV logic yourself — useful in notebooks, automation scripts, and quick data tasks. This guide shows both the API approach and the native Python csv module approach.

Step-by-step guide

1. Use the REST API from Python: import requests, json; data = [{"name": "Alice", "age": 30}]; r = requests.post('https://quickhelp.dev/api/json-to-csv', json={'input': json.dumps(data), 'mode': 'json-to-csv', 'delimiter': ',', 'flatten': True}); print(r.json()['output'])
2. Or use Python's built-in csv module: import csv, io, json; data = json.loads(open('data.json').read()); buf = io.StringIO(); w = csv.DictWriter(buf, fieldnames=data[0].keys()); w.writeheader(); w.writerows(data); print(buf.getvalue())
3. Write the CSV to a file: Replace io.StringIO() with open('output.csv', 'w', newline='') to write directly to disk. Use encoding='utf-8-sig' if the file will be opened in Excel on Windows — the BOM prevents encoding issues with non-ASCII characters.

Frequently asked questions

Which is faster: the API or Python's csv module?

Python's built-in csv module is faster for large datasets because there is no network round-trip. Use the API for quick one-off conversions or when you need the flatten option without writing custom code.

How do I handle pandas DataFrames?

pandas has built-in JSON and CSV conversion: df = pd.read_json('data.json') then df.to_csv('output.csv', index=False). Use pd.json_normalize(data) if the JSON is nested.