Complete Guide to JSON Formatting: Best Practices and Tools

JSON (JavaScript Object Notation) has become the de facto standard for data exchange in modern web development. Whether you're working with APIs, configuration files, or data storage, properly formatted JSON is crucial for readability, debugging, and maintenance.

What is JSON Formatting?

JSON formatting refers to the process of structuring JSON data with proper indentation, spacing, and organization to make it human-readable. Well-formatted JSON is easier to debug, understand, and maintain.

Example of Unformatted vs Formatted JSON

Unformatted (Minified):

JSON
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{"users":[{"id":1,"name":"John Doe","email":"john@example.com","active":true},{"id":2,"name":"Jane Smith","email":"jane@example.com","active":false}],"total":2,"page":1}

Formatted (Beautified):

JSON
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{
  "users": [
    {
      "id": 1,
      "name": "John Doe",
      "email": "john@example.com",
      "active": true
    },
    {
      "id": 2,
      "name": "Jane Smith",
      "email": "jane@example.com",
      "active": false
    }
  ],
  "total": 2,
  "page": 1
}

JSON Formatting Best Practices

1. Consistent Indentation

Use consistent indentation throughout your JSON files. The most common standards are:

• 2 spaces: Preferred for web APIs and configuration files
• 4 spaces: Common in application configuration
• Tabs: Less common but acceptable for some projects

2. Property Naming Conventions

Choose a consistent naming convention and stick to it:

camelCase (Recommended for JavaScript):

JSON
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{
  "firstName": "John",
  "lastName": "Doe",
  "phoneNumber": "+1-555-0123"
}

snake_case (Common in Python/Ruby APIs):

JSON
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{
  "first_name": "John",
  "last_name": "Doe",
  "phone_number": "+1-555-0123"
}

kebab-case (Less common):

JSON
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{
  "first-name": "John",
  "last-name": "Doe",
  "phone-number": "+1-555-0123"
}

3. Logical Property Ordering

Organize properties in a logical order:

1. ID fields first: id, uuid, key
2. Core properties: name, title, type
3. Descriptive fields: description, content
4. Metadata: created_at, updated_at, version

JSON
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{
  "id": 123,
  "name": "Product Name",
  "description": "Product description",
  "price": 29.99,
  "category": "electronics",
  "created_at": "2025-01-01T00:00:00Z",
  "updated_at": "2025-01-15T12:30:00Z"
}

4. Array Formatting

For arrays with objects, each object should be on its own line:

JSON
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{
  "products": [
    {
      "id": 1,
      "name": "Laptop"
    },
    {
      "id": 2,
      "name": "Mouse"
    }
  ]
}

For simple arrays, you can use single lines for short arrays:

JSON
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{
  "tags": ["electronics", "computers", "accessories"],
  "colors": ["red", "blue", "green"]
}

Common JSON Formatting Mistakes

1. Trailing Commas

JSON
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// ❌ Invalid - trailing comma
{
  "name": "John",
  "age": 30,
}

// ✅ Valid
{
  "name": "John",
  "age": 30
}

2. Single Quotes

JSON
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// ❌ Invalid - single quotes
{
  'name': 'John',
  'age': 30
}

// ✅ Valid - double quotes
{
  "name": "John",
  "age": 30
}

3. Comments

JSON
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// ❌ Invalid - comments not allowed in JSON
{
  "name": "John", // This is a comment
  "age": 30
}

// ✅ Use JSONC or add comments as properties if needed
{
  "_comment": "User data structure",
  "name": "John",
  "age": 30
}

JSON Validation and Error Handling

Common JSON Errors

1. Syntax Errors: Missing quotes, brackets, or commas
2. Type Errors: Incorrect data types
3. Structure Errors: Malformed nested objects or arrays

Validation Tools

• Online Validators: JSONLint, DevToolLab JSON Formatter
• IDE Extensions: JSON validation in VS Code, Sublime Text
• Command Line: jq, python -m json.tool

Performance Considerations

When to Minify JSON

Minify JSON for:

• Production APIs: Reduce bandwidth and transfer time
• Configuration files: When file size matters
• Data storage: Minimize storage requirements

When to Keep JSON Formatted

Keep JSON formatted for:

• Development: Easier debugging and maintenance
• Documentation: Examples in API docs
• Configuration files: When human readability is important

Tools for JSON Formatting

Online Tools

• DevToolLab JSON Formatter: Free, privacy-focused formatting
• JSONLint: Popular online validator
• JSON Formatter & Validator: Simple formatting tool

Command Line Tools

Bash
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# Using jq
cat data.json | jq '.'

# Using Python
python -m json.tool data.json

# Using Node.js
node -e "console.log(JSON.stringify(JSON.parse(require('fs').readFileSync('data.json')), null, 2))"

IDE Extensions

• VS Code: Built-in JSON formatting (Alt+Shift+F)
• Sublime Text: JSON Reindent package
• Atom: JSON formatting packages

Advanced JSON Formatting Techniques

Schema-Based Formatting

Use JSON Schema to define structure and validation rules:

JSON
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{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "type": "object",
  "properties": {
    "name": {
      "type": "string",
      "minLength": 1
    },
    "age": {
      "type": "integer",
      "minimum": 0
    }
  },
  "required": ["name", "age"]
}

Conditional Formatting

Format JSON differently based on context:

• API responses: Compact for production, formatted for development
• Configuration files: Always formatted for readability
• Log files: Structured but compact

Conclusion

Proper JSON formatting is essential for maintainable, readable code. By following these best practices and using the right tools, you can ensure your JSON data is well-structured, valid, and easy to work with.

Remember:

• Use consistent indentation (2 or 4 spaces)
• Follow naming conventions
• Validate your JSON regularly
• Choose the right formatting for your use case
• Use appropriate tools for your workflow

Start formatting your JSON properly today with DevToolLab's JSON Formatter - a free, privacy-focused tool that runs entirely in your browser.