JSON Formatting Best Practices for Developers

JSON (JavaScript Object Notation) has become the de facto standard for data exchange on the web. Whether you're working with APIs, configuration files, or storing data, understanding JSON formatting best practices is crucial for writing clean, maintainable code.

What Makes Good JSON?

Good JSON is readable, valid, and follows consistent conventions. Here are the key principles:

1. Always Validate Your JSON

Before deploying or sharing JSON, always validate it. Invalid JSON will break your application at runtime. Common validation errors include:

- Missing or extra commas - Unquoted property names - Single quotes instead of double quotes - Trailing commas in arrays or objects

Use our free JSON Formatter tool to automatically validate and format your JSON with detailed error messages.

2. Use Consistent Indentation

For human-readable JSON, use 2 or 4 spaces for indentation. Never mix tabs and spaces.

Good:

{
  "name": "John Doe",
  "age": 30,
  "skills": ["JavaScript", "Python"]
}

Bad:

{"name":"John Doe","age":30,"skills":["JavaScript","Python"]}

3. Follow Naming Conventions

Choose a naming convention and stick to it throughout your JSON:

- camelCase: firstName, lastName (JavaScript standard) - snake_case: first_name, last_name (Python, Ruby standard) - kebab-case: first-name, last-name (less common in JSON)

Recommendation: Use camelCase for web APIs since JSON is JavaScript-based.

4. Keep It Flat When Possible

Deeply nested JSON is harder to read and maintain. If you find yourself nesting more than 3-4 levels deep, consider restructuring your data.

Too Deep:

{
  "user": {
    "profile": {
      "settings": {
        "notifications": {
          "email": true
        }
      }
    }
  }
}

Better:

{
  "user": {
    "profileSettings": {
      "emailNotifications": true
    }
  }
}

5. Use Arrays for Collections

Always use arrays for collections of items, even if there's only one item currently.

Good:

{
  "users": [
    {"id": 1, "name": "Alice"}
  ]
}

Bad:

{
  "user": {"id": 1, "name": "Alice"}
}

Performance Optimization

Minify for Production

While formatted JSON is great for development, minified JSON reduces file size by removing whitespace. This improves:

- Load times for API responses - Storage efficiency - Network bandwidth usage

Use our free JSON Minifier tool to reduce file size by up to 40% for production deployments.

Consider GZIP Compression

Most modern web servers support GZIP compression. Combined with minification, you can reduce JSON payload sizes significantly:

- Formatted JSON: 1000 bytes - Minified JSON: 600 bytes - Minified + GZIP: 200 bytes

Security Considerations

Never Store Sensitive Data Unencrypted

Avoid storing passwords, API keys, or tokens directly in JSON files:

Don't:

{
  "apiKey": "sk_live_abc123xyz789",
  "password": "mypassword123"
}

Do: Use environment variables or secure vaults, reference them indirectly:

{
  "apiKeyRef": "env.API_KEY",
  "authMethod": "oauth2"
}

Validate Input Data

Always validate JSON from external sources before processing. Malformed or malicious JSON can cause:

- Application crashes - Security vulnerabilities - Data corruption

Common JSON Pitfalls to Avoid

1. Trailing Commas

JSON does not allow trailing commas (unlike JavaScript):

{
  "name": "John",
  "age": 30,  // ❌ This trailing comma is invalid
}

2. Comments

JSON does not support comments. If you need documentation, consider:

- Separate documentation files - Using a _comment property (non-standard but works) - Using JSON5 or HJSON for config files that support comments

3. Undefined or NaN Values

JSON only supports null for empty values. undefined, NaN, and Infinity are not valid:

{
  "value": null,        // ✅ Valid
  "invalid": undefined  // ❌ Not valid JSON
}

Free Tools for JSON Development

Speed up your JSON workflow with these free essential tools:

- Free JSON Formatter tool: Beautify and validate JSON with syntax highlighting - Free Hash Generator tool: Check for errors with detailed error messages - Free CSS Minifier tool: Optimize JSON for production

Conclusion

Following JSON best practices ensures your data is readable, maintainable, and performs well in production. Remember to validate, use consistent formatting, and minify for production deployments.

Start formatting your JSON properly today with our free JSON tools!