JSON Stringifier

Convert JavaScript objects, arrays, and values to properly formatted JSON strings. Perfect for developers who need to serialize data for APIs, storage, or transmission.

What is JSON Stringification?

JSON stringification converts JavaScript objects, arrays, primitives, and other values into JSON string format. This process is essential for data serialization, API communication, and storage.

Features

• JavaScript to JSON: Convert any JavaScript value to JSON
• Custom replacer functions: Transform or filter data during conversion
• Flexible indentation: Choose from minified to fully formatted output
• Error handling: Clear feedback for invalid JavaScript
• Copy functionality: Copy stringified JSON easily
• Download support: Save as JSON file
• Sample data: Includes JavaScript examples for testing

How to use this tool

1. Enter JavaScript object/array/variable in the input field
2. Optionally add a replacer function to transform the data
3. Select your preferred indentation level
4. Click "Stringify JSON" to convert
5. Copy or download the resulting JSON

Input Types Supported

• Objects: Plain JavaScript objects
• Arrays: Arrays with any data types
• Primitives: Strings, numbers, booleans, null
• Mixed data: Complex nested structures
• Variables: Any JavaScript expression

Replacer Function

The replacer function allows you to transform or filter data during stringification:

// Example: Remove sensitive data
if (key === 'password' || key === 'email') return undefined;
return value;

Common replacer use cases:

• Remove sensitive information (passwords, emails)
• Transform data types (dates to strings)
• Filter specific properties
• Modify values based on conditions
• Remove circular references

Indentation Options

• 0: Minified (no indentation, smallest size)
• 1-4 spaces: Readable formatting with custom spacing
• Consistent: Maintains structure while improving readability

Example

Input JavaScript:

const user = {
  name: "John Doe",
  age: 30,
  email: "john@example.com",
  active: true,
  createdAt: new Date('2025-01-15'),
  scores: [95, 87, 92, 88],
  metadata: {
    lastLogin: new Date('2025-01-20T10:30:00Z'),
    preferences: {
      theme: "dark",
      notifications: true
    }
  }
}

Stringified JSON (2 spaces):

{
  "name": "John Doe",
  "age": 30,
  "email": "john@example.com",
  "active": true,
  "createdAt": "2025-01-15T00:00:00.000Z",
  "scores": [
    95,
    87,
    92,
    88
  ],
  "metadata": {
    "lastLogin": "2025-01-20T10:30:00.000Z",
    "preferences": {
      "theme": "dark",
      "notifications": true
    }
  }
}

With Replacer (removing email and dates):

{
  "name": "John Doe",
  "age": 30,
  "active": true,
  "scores": [
    95,
    87,
    92,
    88
  ],
  "metadata": {
    "preferences": {
      "theme": "dark",
      "notifications": true
    }
  }
}

Best practices

• Always handle circular references in your data
• Remove sensitive information before stringifying
• Consider the target system when choosing indentation
• Use replacer functions for data transformation
• Validate input data before stringification
• Consider using libraries like flatted for circular references

Common use cases

• API requests: Prepare data for HTTP requests
• Local storage: Store complex data in browser storage
• Configuration files: Generate config files programmatically
• Data export: Export application data to JSON
• Debug logging: Log complex objects in readable format
• Data migration: Transform data between formats
• Testing: Generate test data fixtures

Supported Data Types

FAQ

What's the difference between JSON.stringify() and this tool? This tool provides a user-friendly interface with additional features like custom indentation, replacer functions, error handling, and file operations.

Can I stringify functions or undefined values? Functions are omitted during stringification, and undefined values are also omitted. Use a replacer function to handle these cases.

How do I handle circular references? JavaScript's JSON.stringify() doesn't handle circular references by default. Use a library like flatted or implement a custom replacer function.

Can I control which properties are included? Yes, use a replacer function to filter properties or transform values before stringification.

What's the maximum data size I can stringify? There's no strict limit, but very large objects may impact browser performance. Consider processing large datasets in chunks.

Related tools on ChangeBlogger

• JSON Unstringifier – for converting JSON strings back to JavaScript
• JSON Prettifier – for formatting existing JSON
• JSON Minifier – for compressing JSON files
• JSON Validator – for checking JSON syntax
• JSON to CSV Converter – for converting JSON to spreadsheet format