JSON Formatter & Validator

Format, validate, and minify JSON data instantly. Perfect for developers, API testing, and data processing with real-time syntax validation.

JSON Formatter & Validator

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JSON Format Guide

Data Types

String: "text""Hello World"
Number: integer/float42, 3.14
Boolean: true/falsetrue, false
Null: null valuenull
Array: [values][1, 2, 3]
Object: {"key": "value"}{"name": "John"}

Common Use Cases

  • API response formatting and validation
  • Configuration file cleanup and debugging
  • Database query result processing
  • JavaScript object structure analysis
  • Data import/export between systems
  • JSON minification for production

JSON Syntax Rules

  • • Keys must be strings in double quotes
  • • Strings must use double quotes, not single quotes
  • • No trailing commas allowed
  • • No comments allowed in JSON
  • • No undefined values (use null instead)
  • • Numbers cannot start with leading zeros

What is JSON?

JSON Basics

JSON (JavaScript Object Notation) is a lightweight, text-based data interchange format. Despite its name, JSON is language-independent and is used across many programming languages.

  • • Human-readable: Easy to read and write
  • • Lightweight: Minimal syntax overhead
  • • Language-agnostic: Works with any programming language
  • • Web-standard: Native browser support
  • • Structured: Hierarchical data representation

Common Applications

  • • REST APIs: Request/response data format
  • • Configuration Files: Application settings
  • • Data Storage: NoSQL databases like MongoDB
  • • AJAX Requests: Web application data exchange
  • • Log Files: Structured logging format
  • • Package Manifests: npm, composer, pip packages

Tool Features

Format & Pretty Print

  • • Automatic indentation with customizable spacing
  • • Proper line breaks for readability
  • • Consistent formatting style
  • • Color syntax highlighting
  • • Real-time formatting as you type

Validate & Debug

  • • Real-time syntax validation
  • • Precise error location reporting
  • • Detailed error descriptions
  • • JSON structure analysis
  • • Depth and key count metrics

Minify & Optimize

  • • Remove unnecessary whitespace
  • • Reduce file size for production
  • • Compression ratio calculation
  • • Bandwidth optimization
  • • API payload optimization

JSON Best Practices

✅ Good Practices

  • • Use consistent naming conventions (camelCase or snake_case)
  • • Keep nesting levels reasonable (avoid deep hierarchies)
  • • Use meaningful key names that describe the data
  • • Validate JSON before sending to APIs
  • • Use arrays for homogeneous data collections
  • • Include version information for API schemas
  • • Use null for missing values, not empty strings

❌ Common Mistakes

  • • Using single quotes instead of double quotes
  • • Adding trailing commas after last elements
  • • Including JavaScript comments (not allowed in JSON)
  • • Using undefined values (use null instead)
  • • Forgetting to escape special characters in strings
  • • Using non-string keys in objects
  • • Creating circular references in data structures

Real-World Examples

API Response

{
  "status": "success",
  "data": {
    "users": [
      {
        "id": 1,
        "name": "John Doe",
        "email": "[email protected]",
        "roles": ["admin", "user"],
        "lastLogin": "2024-01-15T10:30:00Z",
        "settings": {
          "theme": "dark",
          "notifications": true
        }
      }
    ]
  },
  "meta": {
    "total": 1,
    "page": 1,
    "limit": 10
  }
}

Configuration File

{
  "name": "my-web-app",
  "version": "1.2.3",
  "description": "A sample web application",
  "main": "app.js",
  "scripts": {
    "start": "node app.js",
    "dev": "nodemon app.js",
    "test": "jest"
  },
  "dependencies": {
    "express": "^4.18.0",
    "mongoose": "^6.0.0"
  },
  "engines": {
    "node": ">=14.0.0"
  }
}

Programming Language Support

JavaScript/Node.js

// Parse JSON string
const obj = JSON.parse(jsonString);

// Convert to JSON string
const json = JSON.stringify(obj);

// Pretty print with indentation
const pretty = JSON.stringify(obj, null, 2);

Python

import json

# Parse JSON string
obj = json.loads(json_string)

# Convert to JSON string
json_str = json.dumps(obj)

# Pretty print with indentation
pretty = json.dumps(obj, indent=2)

Troubleshooting Common Errors

Unexpected token error

Cause: Usually due to trailing commas, missing quotes, or unescaped characters

❌ {"name": "John",}→✅ {"name": "John"}

Unexpected end of input

Cause: Missing closing braces or brackets

❌ {"name": "John"→✅ {"name": "John"}

Invalid property name

Cause: Property names must be in double quotes

❌ {name: "John"}→✅ {"name": "John"}

Privacy & Security

Client-Side Processing

  • • All JSON processing happens in your browser
  • • No data is sent to external servers
  • • Works completely offline once loaded
  • • Safe for sensitive configuration files
  • • No logging or storage of your JSON data

Security Considerations

  • • Never include secrets or passwords in JSON files
  • • Validate JSON before processing in applications
  • • Be cautious with deeply nested objects (DoS risk)
  • • Sanitize user input before JSON serialization
  • • Use HTTPS when transmitting JSON over networks