10 Essential JSON Formatting Tips for Developers

JSON (JavaScript Object Notation) has become the de facto standard for data exchange in modern web applications. Proper formatting not only improves readability but also makes debugging easier and ensures better maintainability. Here are 10 essential tips every developer should know.

1. Use Consistent Indentation

Consistent indentation is crucial for readability. Whether you choose 2 or 4 spaces, stick with it throughout your project. Most modern editors and formatters default to 2 spaces, which is a good balance between readability and file size.

{
  "name": "John Doe",
  "age": 30,
  "address": {
    "street": "123 Main St",
    "city": "New York"
  }
}

2. Always Use Double Quotes

JSON specification requires double quotes for strings and keys. While some parsers are lenient, using single quotes or unquoted keys can cause issues with strict parsers and validation tools.

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

// ❌ Incorrect
{
  'name': 'John',
  age: 30
}

3. Avoid Trailing Commas

Trailing commas are not allowed in JSON. While they're valid in JavaScript, they will cause JSON parsing errors. Always remove the comma after the last item in objects and arrays.

// ✅ Correct
{
  "items": ["apple", "banana", "orange"]
}

// ❌ Incorrect
{
  "items": ["apple", "banana", "orange",]
}

4. Validate Before Deployment

Always validate your JSON before deploying to production. Use online validators or build-time validation tools to catch syntax errors early. This prevents runtime errors and improves application reliability.

5. Use Meaningful Key Names

Choose descriptive, camelCase key names that clearly indicate their purpose. Avoid abbreviations unless they're widely understood in your domain.

// ✅ Good
{
  "firstName": "John",
  "lastName": "Doe",
  "emailAddress": "john@example.com"
}

// ❌ Poor
{
  "fn": "John",
  "ln": "Doe",
  "em": "john@example.com"
}

6. Keep Structures Flat When Possible

While nested structures are sometimes necessary, flatter structures are easier to work with and query. Consider denormalizing data when it improves performance and readability.

7. Use Arrays for Lists, Objects for Entities

Use arrays for collections of similar items and objects for entities with multiple properties. This makes the data structure more intuitive and easier to iterate over.

// ✅ Good structure
{
  "users": [
    { "id": 1, "name": "John" },
    { "id": 2, "name": "Jane" }
  ]
}

8. Handle Null Values Explicitly

Use null explicitly for missing values rather than omitting keys. This makes the data structure predictable and easier to work with in strongly-typed languages.

9. Minify for Production, Format for Development

Use minified JSON in production to reduce file size and improve load times. During development, use formatted JSON for better readability and debugging.

10. Use Tools for Large Files

For large JSON files, use dedicated formatting and validation tools. Online formatters like SmartFormatter can handle complex structures and provide instant feedback on errors.