How to Pretty Print JSON in Python: Simple Guide

To pretty print JSON in Python, use the json.dumps() function with the indent parameter set to a number of spaces for indentation. This formats the JSON string with line breaks and indentation for easy reading.

Syntax

The basic syntax to pretty print JSON in Python uses the json.dumps() function with the indent argument. Here is what each part means:

• json.dumps(obj): Converts a Python object obj to a JSON string.
• indent=number: Adds line breaks and spaces to format the JSON output. The number sets how many spaces to use for each indentation level.

python

import json

json_string = json.dumps(obj, indent=4)

Example

This example shows how to pretty print a Python dictionary as JSON with 4 spaces indentation. It makes the JSON output easy to read by adding new lines and spaces.

python

import json

# Sample Python dictionary
person = {
    "name": "Alice",
    "age": 30,
    "city": "New York",
    "hobbies": ["reading", "hiking", "coding"]
}

# Convert to pretty printed JSON string
pretty_json = json.dumps(person, indent=4)

# Print the formatted JSON
print(pretty_json)

Output

{
    "name": "Alice",
    "age": 30,
    "city": "New York",
    "hobbies": [
        "reading",
        "hiking",
        "coding"
    ]
}

Common Pitfalls

Some common mistakes when pretty printing JSON in Python include:

• Forgetting to import the json module.
• Not using json.dumps() but trying to print the Python object directly, which won't format as JSON.
• Using print(json.dumps(obj)) without indent will print JSON in one line, not pretty.
• Confusing json.dumps() (returns string) with json.dump() (writes to file).

Example of wrong and right way:

python

import json

data = {"key": "value"}

# Wrong: prints Python dict, not JSON string
print(data)

# Wrong: JSON string but no pretty print
print(json.dumps(data))

# Right: pretty print with indent
print(json.dumps(data, indent=2))

Output

{'key': 'value'}
{"key": "value"}
{
  "key": "value"
}

Quick Reference

Tips for pretty printing JSON in Python:

• Use json.dumps(obj, indent=4) for readable JSON strings.
• Use indent value to control spaces per level.
• Use sort_keys=True to sort keys alphabetically.
• Use json.dump(obj, file, indent=4) to write pretty JSON directly to a file.

Key Takeaways

Use json.dumps() with indent parameter to pretty print JSON strings.

Indent controls the number of spaces for each level of nesting.

json.dumps() returns a string; use print() to display it.

json.dump() writes JSON directly to a file with optional pretty print.

Always import the json module before using its functions.