How to Comment Out in JSON: Complete Guide

JSON (JavaScript Object Notation) is a lightweight data interchange format that has become the standard for data exchange on the web. While JSON offers simplicity and readability, one common frustration for developers is the lack of native support for comments. Unlike other formats like JavaScript, Python, or XML, JSON doesn't provide a standard way to add comments directly within the data structure.

So, how can you add comments to your JSON files? In this comprehensive guide, we'll explore various workarounds, best practices, and tools to help you effectively comment out information in JSON without breaking the format's integrity.

Why JSON Doesn't Support Comments Natively

The JSON specification intentionally excludes comments for several reasons. First, it keeps the format minimal and focused on data representation. Second, it ensures that JSON parsers remain simple and fast, as they don't need to interpret comment syntax. Finally, it maintains strict data typing, preventing comments from being accidentally interpreted as data values.

However, this limitation creates challenges when developers need to document their JSON structures or temporarily disable certain elements during development and testing.

Common Workarounds for Commenting in JSON

1. Using a "_comment" Key

One popular approach is to use a special key like "_comment" or "comment" to store comment information. This keeps comments within the JSON structure while making it clear they're not part of the actual data.

{
  "name": "John Doe",
  "age": 30,
  "_comment": "This user profile is for demonstration purposes only",
  "isActive": true
}

2. Placing Comments Outside the JSON

You can place comments outside the JSON structure, typically before or after the JSON content. This approach keeps the JSON valid while providing documentation.

// This is a user profile configuration
{
  "name": "John Doe",
  "age": 30,
  "isActive": true
}

// End of configuration

3. Using JSON5 or Extended JSON

JSON5 is an extension of JSON that allows comments and other features not supported in standard JSON. If you're working in an environment that supports JSON5, you can use standard comment syntax (// for single-line and /* */ for multi-line).

{
  // Single-line comment
  "name": "John Doe",
  /* Multi-line
     comment */
  "age": 30,
  "isActive": true
}

4. Using a Separate Comments File

For complex JSON structures, you might maintain a separate file for comments that references the JSON file. This keeps your data clean while providing comprehensive documentation.

Best Practices for JSON with Comments

When implementing any of these workarounds, consider the following best practices:

• Consistency: Choose one method and stick with it throughout your project
• Clear Documentation: Make it obvious which elements are comments and which are actual data
• Tool Compatibility: Ensure your chosen approach works with the tools and systems that will consume your JSON
• Version Control: Consider how comments will be handled in version control systems

When to Use Different Approaches

The best commenting approach depends on your specific use case:

• For API Development: Use the "_comment" key approach to keep all information in one file
• For Configuration Files: Consider using JSON5 if your environment supports it
• For Documentation: Separate comment files work well for large, complex structures
• For Temporary Disabling: Place comments outside the JSON for quick changes

Tools for Working with JSON

Working with JSON, especially with comments, can be challenging. Fortunately, there are many tools available to help streamline your workflow. Our JSON Pretty Print tool can help you format and validate your JSON, making it easier to spot issues and maintain readability.

You can access our JSON Pretty Print tool at JSON Pretty Print to help you format your JSON files properly.