JSON Formatter: Beautify and Validate JSON Online

Transform messy, compact JSON data into clean, readable format with our free online JSON formatter. JSON (JavaScript Object Notation) is a popular data format used by websites and apps to store and exchange information. When working with JSON, it often comes in a single, unreadable line—our beautifier tool formats it with proper indentation and line breaks, making it easy to understand and debug.

Paste your JSON to instantly format, minify, or validate it. Choose between 2 or 4 space indentation or tabs. Sort object keys alphabetically for consistency. See syntax highlighting to quickly spot different data types. View statistics about your JSON structure. Fix formatting errors with helpful error messages. Everything runs in your browser—no data uploaded to any server. 

Formatted JSON will appear here...

What is JSON?

JSON (JavaScript Object Notation) is a lightweight data-interchange format that's easy for humans to read and write, and easy for machines to parse and generate. It's the most common format for transmitting data between a server and web application.

Common Use Cases:

  • API responses and requests
  • Configuration files (package.json, tsconfig.json)
  • Data storage and exchange
  • Web application state management
  • NoSQL database documents (MongoDB)
  • Log files and analytics data

JSON Structure:

Data Types:

  • String: Text in double quotes ("hello")
  • Number: Integer or decimal (42, 3.14)
  • Boolean: true or false
  • Null: null value
  • Array: Ordered list [1, 2, 3]
  • Object: Key-value pairs {"key": "value"}

Example:

Unformatted:

{"name":"John Doe","age":30,"email":"john@example.com","active":true}

Formatted:

{
  "name": "John Doe",
  "age": 30,
  "email": "john@example.com",
  "active": true
}

Features:

  • Format/beautify JSON with custom indentation (2/4 spaces or tabs)
  • Minify JSON to reduce file size
  • Sort object keys alphabetically
  • Real-time validation with error messages
  • Structure statistics (keys, objects, arrays count)
  • One-click copy to clipboard
  • 100% client-side - your data never leaves your browser

Common JSON Errors:

Trailing Commas:

// ❌ Invalid
{ "name": "John", }

// ✅ Valid
{ "name": "John" }

Single Quotes:

// ❌ Invalid
{ 'name': 'John' }

// ✅ Valid
{ "name": "John" }

Unquoted Keys:

// ❌ Invalid
{ name: "John" }

// ✅ Valid
{ "name": "John" }

JSON vs JavaScript Object:

While JSON is based on JavaScript object notation, there are key differences:

  • JSON keys must be strings in double quotes
  • JSON doesn't support functions, dates, or undefined
  • JSON doesn't allow comments
  • JSON doesn't support trailing commas

When to Format vs Minify:

  • Format: For debugging, reading, and editing JSON data
  • Minify: For production APIs, reducing file size, and network transfer
  • Sort Keys: For consistent diffs, version control, and comparing JSON

Best Practices:

  • Always validate JSON before deploying to production
  • Use consistent key naming (camelCase, snake_case)
  • Keep structure flat when possible for better performance
  • Minify JSON for APIs to reduce bandwidth
  • Use proper data types (numbers vs strings for numeric values)

Frequently Asked Questions

What is JSON and why does it need formatting? +

JSON (JavaScript Object Notation) is a lightweight data format used to store and exchange data between servers and web applications. Raw JSON is often minified (compressed into one line) for efficiency. Formatting adds proper indentation and line breaks, making it human-readable for debugging, editing, and understanding data structures.

What's the difference between formatting and minifying JSON? +

Formatting (beautifying) adds whitespace, indentation, and line breaks to make JSON readable. Minifying removes all unnecessary whitespace to create the smallest possible file size. Use formatting for development and debugging; use minifying for production to reduce bandwidth and improve load times.

How do I validate JSON? +

Our formatter automatically validates JSON as you paste it. Valid JSON must have properly matched brackets and braces, strings in double quotes, no trailing commas, and correct data types. If your JSON is invalid, you'll see an error message showing where the problem is located.

What does 'sort keys' do? +

Sorting keys arranges all object properties alphabetically (a-z). This is useful for comparing JSON files, maintaining consistency across your codebase, and making it easier to find specific keys in large objects. Sorting is applied recursively to all nested objects.

Can I format JSON with different indentation styles? +

Yes! Our formatter supports 2 spaces (common in JavaScript), 4 spaces (common in Python/Java), and tabs. Choose whichever matches your project's coding standards. The indentation preference doesn't affect the data—only how it's displayed.