JSON Formatter

Format, validate and beautify JSON data.

Indent:

Input JSON

Formatted output

{
  "name": "Alice",
  "age": 30,
  "hobbies": [
    "reading",
    "coding"
  ]
}

What is JSON and why format it?

JSON (JavaScript Object Notation) is the standard data interchange format for APIs, configuration files, and web applications. Raw JSON from an API or database is often a compact single line with no whitespace — efficient for transmission but unreadable for humans. A formatter adds consistent indentation and line breaks to make the structure visually clear, making debugging and review dramatically faster.

Compact (API response):
{"user":{"id":1,"name":"Alice","roles":["admin","editor"],"active":true}}

Formatted (readable):
{
  "user": {
    "id": 1,
    "name": "Alice",
    "roles": [
      "admin",
      "editor"
    ],
    "active": true
  }
}

JSON data types

String

"Hello World"

Must use double quotes. Single quotes are invalid JSON.

Number

42 or 3.14

Integer or float. No quotes. No leading zeros.

Boolean

true or false

Lowercase only. "True" is invalid.

Null

null

Represents absence of value. Lowercase only.

Object

{"key": value}

Key-value pairs. Keys must be strings.

Array

[1, "a", true]

Ordered list. Can mix types.

Common JSON validation errors

Error	Invalid	Valid
Single quotes for strings	{'name': 'Alice'}	{"name": "Alice"}
Trailing comma	{"a": 1, "b": 2,}	{"a": 1, "b": 2}
Unquoted keys	{name: "Alice"}	{"name": "Alice"}
Comments	{"a": 1 // comment}	{"a": 1}
Undefined value	{"a": undefined}	{"a": null}
NaN or Infinity	{"n": NaN}	{"n": null}

Frequently asked questions

What does a JSON formatter do?

It takes minified or messy JSON and re-indents it with consistent spacing so it is easy to read, and it validates the syntax, flagging errors like missing commas or brackets.

Is my JSON sent to a server?

No. Formatting and validation run entirely in your browser, so your data stays private.

Why is my JSON invalid?

The most common causes are trailing commas, single quotes instead of double quotes, unquoted keys, or a missing closing bracket. The validator points to where parsing fails.

What is the difference between formatting and minifying JSON?

Formatting adds indentation and line breaks for humans; minifying removes all unnecessary whitespace to make the payload smaller for transfer. Both represent the same data.

What this tool does

Formats, validates and beautifies raw JSON text. Paste minified or messy JSON on the left and get a nicely indented, human-readable version on the right. Also highlights syntax errors with the exact error message.

Input fields explained

Input JSON

Paste any JSON here — minified, partially formatted, or from an API response. The formatter parses and re-serializes it.

Indent

2 spaces is the most common convention. 4 spaces is used in some style guides. Both are equally valid JSON.

Formula / How it works

Parses the JSON and re-serializes with proper indentation. Also validates the JSON and shows syntax errors.