json.dumps() in Python (original) (raw)

Last Updated : 13 Jan, 2026

The json.dumps() function in Python converts a Python object (such as a dictionary or list) into a JSON-formatted string. It is mainly used when you need to send data over APIs, store structured data or serialize Python objects into JSON text.

**Example: This example shows how to convert a Python dictionary into a JSON string.

Python `

import json d = {"a": "Hello", "b": "World"} s = json.dumps(d) print(s) print(type(s))

`

Output

{"a": "Hello", "b": "World"} <class 'str'>

**Explanation:

• json.dumps(d) converts the dictionary d into a JSON string.
• The output type is str, not a dictionary.

Syntax

json.dumps(obj, skipkeys=False, ensure_ascii=True, allow_nan=True, indent=None, separators=None, sort_keys=False)

**Parameters:

• **obj: Python object to convert (dict, list, string, etc.)
• **skipkeys: Ignores unsupported keys instead of raising an error
• **ensure_ascii: Escapes non-ASCII characters if True
• **allow_nan: Allows NaN, Infinity values
• **indent: Formats JSON with indentation
• **separators: Custom separators for items and key–value pairs
• **sort_keys: Sorts dictionary keys alphabetically

**Return Type: string object (str).

Examples

**Example 1: This example demonstrates how skipkeys=True ignores dictionary keys that are not JSON-compatible.

Python `

import json d = {("x", "y"): 10, "a": 1} s = json.dumps(d, skipkeys=True) print(s)

`

**Explanation:

• JSON does not support tuple keys.
• skipkeys=True removes invalid keys automatically.

**Example 2: This example formats JSON output to make it more readable using indentation.

Python `

import json d = {"a": 1, "b": 2, "c": 3} s = json.dumps(d, indent=4) print(s)

`

Output

{ "a": 1, "b": 2, "c": 3 }

**Explanation:

• indent=4 adds spacing and line breaks.
• The JSON string becomes easy to read.

**Example 3: This example sorts dictionary keys alphabetically before converting them to JSON.

Python `

import json d = {"c": 3, "a": 1, "b": 2} s = json.dumps(d, sort_keys=True) print(s)

`

Output

{"a": 1, "b": 2, "c": 3}

**Explanation:

• sort_keys=True sorts keys alphabetically.
• Useful for consistent JSON output.

**Example 4: This example shows how json.dumps() converts a Python list into a JSON-formatted string, which is commonly used when sending list data through APIs.

Python `

import json lst = [10, 20, 30, 40] s = json.dumps(lst) print(s)

`