JSON Best Practices

Write clean, maintainable JSON for APIs and configurations

10 min readDeveloper Guide

Why JSON Best Practices Matter

JSON is everywhere—APIs, configuration files, data storage, and inter-service communication. Well-structured JSON makes your systems more maintainable, debuggable, and efficient. Poorly written JSON leads to parsing errors, confusion, and technical debt.

This guide covers the most important best practices for writing clean, maintainable JSON. Follow these patterns and your JSON will be easier to read, debug, and integrate across systems.

Key Best Practices

1. Use Consistent Naming Conventions

Choose a naming style and stick to it throughout your JSON. The most common conventions:

camelCase (Recommended)

{"firstName": "John", "lastName": "Doe"}

Most common in JavaScript/TypeScript APIs

snake_case

{"first_name": "John", "last_name": "Doe"}

Common in Python/Ruby APIs and database fields

kebab-case (Avoid in keys)

{"first-name": "John"} // Not recommended

Requires quotes in many languages, harder to parse

Tip: Match your API's naming convention to your primary programming language. JavaScript projects should use camelCase, Python projects snake_case.

2. Design Clean Structure

Keep your JSON structure flat when possible. Deeply nested JSON is harder to read, query, and debug. Aim for 2-3 levels of nesting maximum.

✓ Good: Flat Structure

{
  "userId": 123,
  "userName": "John",
  "userEmail": "[email protected]"
}

✗ Bad: Deep Nesting

{
  "data": {
    "user": {
      "profile": {
        "identity": {
          "name": "John"
        }
      }
    }
  }
}

Deep nesting increases complexity without adding value. Use arrays for collections and objects for grouping related fields.

3. Use Arrays for Collections

When you have multiple items of the same type, use arrays. Don't use numbered keys as a substitute for arrays.

✓ Good: Use Arrays

{
  "users": [
    {"id": 1, "name": "Alice"},
    {"id": 2, "name": "Bob"}
  ]
}

✗ Bad: Numbered Keys

{
  "user1": {"id": 1, "name": "Alice"},
  "user2": {"id": 2, "name": "Bob"}
}

Arrays are easier to iterate, filter, and map in code. Numbered objects require extra parsing logic and can't use standard array methods.

4. Include Schema Version

For configuration files and API responses that evolve over time, include a version field. This enables backward compatibility and migration strategies.

{
  "version": "2.0",
  "data": {
    // v2.0 structure
  }
}

When you change the structure, increment the version. Code can check the version and handle different formats appropriately.

5. Handle Missing Values Consistently

Decide whether to use null, omit fields, or use default values. Document your choice and stick to it.

Omit field: Field doesn't exist, never was set (cleanest for optional fields)

Use null: Field exists but has no value (explicit empty)

Use default: Field always has a value (simplifies parsing)

Recommendation: Omit optional fields rather than setting null. It reduces payload size and simplifies schema validation.

6. Validate Before Use

Always validate JSON before parsing or storing. Invalid JSON causes crashes and data corruption.

Validate JSON Repair JSON

Use JSON Schema for complex validation requirements. Schema defines expected structure, types, and constraints—catching errors early in development.

Common JSON Mistakes to Avoid

Single Quotes Instead of Double

JSON requires double quotes for strings. Single quotes are JavaScript, not JSON.

// Invalid JSON:
{'name': 'John'}

// Valid JSON:
{"name": "John"}

Trailing Commas

JSON doesn't allow trailing commas after the last element in arrays or objects.

// Invalid JSON:
{"items": [1, 2, 3,]}

// Valid JSON:
{"items": [1, 2, 3]}

Comments in JSON

JSON doesn't support comments. Use JSONC (JSON with Comments) or separate documentation.

// Invalid JSON:
{
  "name": "John", // user name
  "age": 30
}

// Use separate docs or JSONC format instead

Unquoted Keys

All keys must be quoted in JSON, unlike JavaScript objects.

// Invalid JSON:
{name: "John"}

// Valid JSON:
{"name": "John"}

Performance Tips

Minify for Production: Remove whitespace to reduce file size and network transfer time
Avoid Large Arrays: Consider pagination or chunking for arrays with thousands of items
Use Numbers for IDs: Number IDs parse faster than string IDs in most languages
Short Keys: Use short but meaningful key names to reduce payload size