JSON (JavaScript Object Notation) has become ubiquitous in modern web development and data interchange due to its simplicity and ease of use. However, one persistent limitation developers face is the lack of support within JSON file comment. In this blog post, we will delve into why JSON doesn't support comments, explore the need for comments in JSON files, discuss workarounds to include comments, provide practical examples, highlight useful tools and libraries, and conclude with best practices for managing JSON files effectively.
What is JSON?
JSON, short for JavaScript Object Notation, is a lightweight data-interchange format that's both easy for humans to read and write, and easy for machines to parse and generate. It consists of key-value pairs and arrays, making it ideal for transmitting data between a server and a client or between different parts of an application.
Why JSON Doesn't Support Comments
The design philosophy behind JSON emphasizes simplicity and data interchangeability. To maintain this simplicity, JSON deliberately omits support for comments. Unlike programming languages or markup languages where comments aid readability and documentation, JSON focuses purely on data representation.
The Need for Comments in JSON Files
Despite JSON's simplicity, there are numerous scenarios where comments within JSON files could greatly enhance understanding and maintainability. Comments can provide essential context, document decisions, and explain the purpose of various data elements within the file. This is especially crucial in configuration files and complex data structures where clarity is paramount.
Workarounds for Adding Comments to JSON

1. Using an External Documentation File One workaround is to maintain an external documentation file alongside your JSON file. This separate document can contain detailed explanations, annotations, and comments that provide context for each section or key-value pair within the JSON structure. While this approach keeps the JSON file itself pure and compliant, it requires developers to manage two separate files.
2. Using Special Fields for Comments Another approach involves leveraging special fields within the JSON structure that are treated as comments. Although these fields don't conform strictly to the JSON standard, they allow developers to embed comments directly within the data structure. This method can be effective for small to medium-sized JSON files where maintaining a separate documentation file might be overkill.
3. Preprocessing JSON Files For more advanced scenarios, preprocessing JSON files before parsing can be a viable solution. This involves stripping out comments from the JSON file programmatically before it's consumed by the application. While it requires additional development effort, it ensures that comments don't interfere with the parsing process and maintains JSON compliance. Practical Examples Let's explore practical examples to illustrate these workarounds: Example of External Documentation Consider a configuration file config.json alongside a config.json.md Markdown file. The Markdown file can contain detailed explanations and comments for each configuration option, ensuring clarity without cluttering the JSON file itself. Example of Special Fields In this example, we can add a _comment field for each key-value pair in the JSON file: json Copy code { "name": "John Doe", "_comment": "User's full name" } This approach allows developers to include comments directly within the JSON structure, albeit with non-standard fields. Example of Preprocessing By using a preprocessing script, comments can be removed from the JSON file before parsing: json Copy code { "name": "Jane Smith" // This comment will be removed during preprocessing } The preprocessing script would strip out such comments, ensuring the JSON file remains compliant for parsing. Tools and Libraries Several tools and libraries can aid in managing comments within JSON files: JSON Comment Stripper The JSON Comment Stripper is a tool designed specifically to remove comments from JSON files before they are parsed. It simplifies the process of ensuring JSON compliance while allowing for human-readable comments during development. Custom JSON Parsers Developers can also create custom JSON parsers tailored to their specific needs. These parsers can be configured to ignore or process comment-like structures within JSON files, providing flexibility in how comments are managed. Best Practices When working with JSON files, adhere to these best practices: Maintain Clear Documentation Always maintain clear and comprehensive documentation alongside your JSON files. Whether through external files or embedded comments, documentation is crucial for understanding data structures and configurations. Use Readable Naming Conventions Employ readable and descriptive naming conventions for keys and fields within your JSON files. Clear naming reduces the need for extensive comments and enhances readability. Conclusion While JSON itself doesn't support comments, the techniques and tools discussed in this post enable developers to effectively document and manage JSON files in real-world applications. Whether through external documentation, special fields, or preprocessing, these workarounds provide flexibility without compromising JSON's simplicity and compatibility. By following best practices and leveraging appropriate tools, developers can enhance clarity, maintainability, and usability of JSON files across their projects. Understanding these methods ensures that JSON remains a versatile and efficient format for data interchange in modern software development.