JSON Formatter — Free, Instant & Online

What Is a JSON Formatter?

A JSON formatter takes raw, unindented, or invalid JSON and transforms it into clean, readable output with proper indentation, line breaks, and syntax highlighting. It also validates the JSON structure, pinpointing any syntax errors so you can fix them instantly. Whether you’re debugging an API response, reading a config file, or reviewing a data export, a formatter turns a wall of text into something you can actually work with.

How to Use This Tool

1. Paste your JSON into the input field — or click the file icon to load sample data.
2. The output updates live as you type. Switch off live mode if you prefer to click “Prettify” manually.
3. Choose your indentation (2 spaces, 4 spaces, or tabs) and toggle Sort keys to alphabetize all object keys.
4. Click Minify to compress your JSON into a single line — ideal for production APIs and storage.
5. Switch to the Tree View tab to explore nested structures interactively. Collapse and expand any object or array.
6. Copy the output to your clipboard or download it as a .json file.

JSON Formatter vs JSON Validator — What’s the Difference?

A JSON formatter (also called a JSON beautifier or JSON prettifier) restructures valid JSON with consistent indentation and spacing. A JSON validator checks whether the JSON syntax is correct according to the JSON specification. This tool does both simultaneously: it validates first and only formats if the JSON is structurally sound. If errors are found, it reports the exact line and position so you can fix the problem fast.

Is This Tool Safe? Your Data Never Leaves Your Browser

Every operation — formatting, validation, minification, tree rendering — happens entirely in JavaScript inside your browser. Nothing is sent to a server. Nothing is stored, logged, or transmitted. This makes it safe to paste API responses, authentication tokens, database exports, or any configuration data containing sensitive information. Close the tab and the data is gone.

Common JSON Errors and How to Fix Them

The validator pinpoints the exact location of every error. Here are the most frequent JSON syntax mistakes:

Trailing Commas

The most common error. JSON does not allow a comma after the last item in an array or object. JavaScript and TypeScript do, which causes constant confusion.

// Invalid JSON
{"name": "Alice", "age": 30,}

// Valid JSON
{"name": "Alice", "age": 30}

Single Quotes Instead of Double Quotes

JSON requires double quotes for all strings and property names. Single quotes are valid in JavaScript but not in JSON.

// Invalid JSON
{'name': 'Alice'}

// Valid JSON
{"name": "Alice"}

Unquoted Property Names

JavaScript objects allow unquoted keys ({name: "Alice"}), but JSON requires every key to be a double-quoted string.

Python-Style Literals

If you’re copying output from a Python script, watch out for True, False, and None — these are not valid JSON. Replace them with true, false, and null.

Comments in JSON

Standard JSON does not support comments. If your JSON file contains // ... or /* ... */ comments, you’ll need to remove them before parsing. JSON5 and JSONC are extensions that support comments, but they are not standard JSON.

Unescaped Backslashes

Windows file paths (e.g. C:\Users\name) must escape backslashes as C:\\Users\\name inside a JSON string.

What Is JSON Pretty Printing?

Pretty printing is the process of adding consistent whitespace — indentation and line breaks — to JSON so it’s easy for humans to read. Minified JSON is compact but unreadable; pretty-printed JSON is structured and scannable. The industry standard is 2-space or 4-space indentation, though tab-indented JSON is common in some codebases. This formatter lets you choose whichever style matches your project or team convention.

When to Use Minify vs Prettify

• Prettify — Use when reading, debugging, reviewing, or documenting JSON. Human-readable output is easier to diff, grep, and comprehend.
• Minify — Use for production APIs, localStorage values, HTTP request payloads, and anywhere where bandwidth and storage size matter. Minified JSON reduces payload size by removing all whitespace.

How to Sort Keys in JSON

Enabling the Sort keys option alphabetically reorders all property names at every level of nesting. This is useful when comparing two JSON objects, normalizing configuration files, or generating consistent output for version control diffs. Sorted JSON makes it easy to spot differences in git diff without noise from reordered keys.

How to Format JSON in Other Environments

Format JSON in the Terminal (jq)

# Pretty-print a JSON file
cat data.json | jq .

# Pretty-print JSON from a curl response
curl -s https://api.example.com/data | jq .

# Minify JSON
cat data.json | jq -c .

Format JSON in Python

import json

# Pretty-print
data = {"name": "Alice", "age": 30}
print(json.dumps(data, indent=2))

# From a file
with open("data.json") as f:
    data = json.load(f)
    print(json.dumps(data, indent=2, sort_keys=True))

Format JSON in JavaScript / Node.js

// Pretty-print
const data = { name: "Alice", age: 30 };
console.log(JSON.stringify(data, null, 2));

// With sorted keys
const sorted = Object.fromEntries(Object.entries(data).sort());
console.log(JSON.stringify(sorted, null, 2));

Format JSON in VS Code

Open a .json file and press Shift + Alt + F (Windows/Linux) or Shift + Option + F (macOS) to auto-format. You can also right-click and select Format Document. VS Code uses Prettier or its built-in JSON formatter — set your preferred indent size in Settings → editor.tabSize.