How do I write JSON data to a file?

How do I write JSON data stored in the dictionary data to a file?

f = open('data.json', 'wb')
f.write(data)

This gives the error:

TypeError: must be string or buffer, not dict

data is a Python dictionary. It needs to be encoded as JSON before writing.

Use this for maximum compatibility (Python 2 and 3):

import json
with open('data.json', 'w') as f:
    json.dump(data, f)

On a modern system (i.e. Python 3 and UTF-8 support), you can write a nicer file using:

import json
with open('data.json', 'w', encoding='utf-8') as f:
    json.dump(data, f, ensure_ascii=False, indent=4)

See json documentation.