How to Format JSON

Method 1: Online (fastest)

Go to quicktoolshub.org/json-formatter. Paste your JSON, choose 2 or 4 space indentation, and click Format JSON. The output is syntax-highlighted and ready to copy. Nothing is sent to a server.

Method 2: JavaScript

// Format an object
const formatted = JSON.stringify(obj, null, 2);

// Format a JSON string (parse first, then re-stringify)
const formatted = JSON.stringify(JSON.parse(rawString), null, 2);

// 4-space indent
const formatted = JSON.stringify(obj, null, 4);

// With sorted keys
const formatted = JSON.stringify(obj, Object.keys(obj).sort(), 2);

Method 3: Python

import json

# Format a dict
print(json.dumps(data, indent=2))

# Format a JSON string
print(json.dumps(json.loads(raw_string), indent=2))

# With sorted keys
print(json.dumps(data, indent=2, sort_keys=True))

# Format a JSON file
with open('input.json') as f:
    data = json.load(f)
with open('output.json', 'w') as f:
    json.dump(data, f, indent=2)

Method 4: Command line

# jq — most popular, colorized output
cat file.json | jq .
echo '{"key":"value"}' | jq .

# Python built-in (any system with Python 3)
python3 -m json.tool file.json
cat file.json | python3 -m json.tool

# Node.js (inline)
node -e "console.log(JSON.stringify(require('./file.json'), null, 2))"

Method 5: VS Code

Open the JSON file. Use Shift+Alt+F (Windows/Linux) or Shift+Option+F (Mac) to format the document. Right-click > Format Document also works. VS Code uses your editor settings for indentation (tab size).

Why JSON formatting matters

Raw JSON from an API or log file is typically minified — all whitespace removed to reduce transmission size. While compact JSON is efficient to send, it is nearly impossible to read or debug. A single minified API response can be thousands of characters on one line. Formatting it with indentation immediately reveals the structure: which keys are nested, where arrays start and end, and which values are strings vs numbers vs booleans.

Validation is equally important. JSON has strict syntax rules: property names must be in double quotes (not single), trailing commas are not allowed, and there is no comment syntax. A single missing comma or extra bracket will cause a parse error in any JSON consumer. Formatting tools that validate as they format catch these errors before they cause silent failures in production code.

2-space indentation is the most common standard, used by npm, Prettier, and most JavaScript style guides. 4-space indentation is preferred in some Python projects and older codebases. Tab indentation is used in a few projects for accessibility reasons (allows users to control indent width). The choice does not affect how the JSON parses — it is purely cosmetic.

Method 6: Node.js / npm

# Format JSON in a script
const fs = require('fs');
const data = JSON.parse(fs.readFileSync('input.json', 'utf8'));
fs.writeFileSync('output.json', JSON.stringify(data, null, 2));

# Using prettier CLI to format JSON files
npx prettier --write "**/*.json"