JSON (JavaScript Object Notation) has become a ubiquitous format for data interchange in web applications, APIs, and configuration files. However, one limitation of JSON is the lack of native support for comments, which has sparked discussions about whether adding comments to JSON is beneficial. This guide explores the importance of comments in JSON, how businesses can implement effective commenting strategies, and best practices for maintaining clear, maintainable JSON files.
Why Comments in JSON Matter
Despite JSON's simplicity, the complexity of data structures, configuration files, and API responses can grow over time. Without comments, it can become difficult to understand the purpose or context of specific fields or data structures, especially in large-scale systems. This is why adding comments (though not natively supported) can provide essential documentation that improves collaboration, debugging, and long-term maintainability.
The Challenge: JSON’s Lack of Native Comment Support
JSON is deliberately designed to be lightweight and easy to parse, and this led to the exclusion of comments in its official specification. However, there are workarounds and alternatives that businesses can use to incorporate comments without violating the standard or introducing parsing issues. These workarounds are critical for adding clarity to JSON files without sacrificing performance or compliance.
Key Strategies for Implementing Comments in JSON

1. Using Non-Standard Comment Fields Since JSON does not support comments in the form of // or /* */, the most common workaround is adding comment-like fields that are ignored by the application but are useful for human readers. • Strategy: Include fields with names like _comment or __note to provide context within your JSON. • Best Practice: Ensure that these fields are placed at strategic points where clarity is required, such as explaining complex configurations or providing context for obscure fields. json Copy code { "_comment": "This configuration is for API version control", "api_version": "v1.2", "settings": { "_note": "Enable debug mode only in development environment", "debug": false } } • Tip: These fields should be easily removable during production deployments to prevent them from affecting performance or cluttering responses.
2. Pre-Processing JSON with Comments Another strategy is to use JSON pre-processing tools that allow comments during development. Once the comments are included, the pre-processor strips them out before the JSON is consumed by the application. • Strategy: Utilize tools like JSON5 or jq to add comments during development while ensuring the final production file is comment-free. • Best Practice: Use a continuous integration (CI) pipeline to automate the process of stripping comments from JSON files before deployment. json5 Copy code { // This is a JSON5 comment "apiVersion": "v2.0", "enableFeatureX": true } • Case Study: A software development company implemented JSON5 for internal configuration management. During development, the team was able to annotate complex configurations, improving collaboration between front-end and back-end teams. The pre-processor removed these comments before deploying the configuration, ensuring that the production environment remained compliant with standard JSON.
3. Leveraging External Documentation An alternative to embedding comments within JSON files is to use external documentation that explains the structure and content of JSON files. This can include adding comments in code that generate or parse the JSON, or maintaining separate documentation files. • Strategy: Create external documentation for large JSON files or complex data structures, especially for APIs where the JSON structure might be consumed by multiple services. • Best Practice: Use documentation generation tools like Swagger or Postman to generate clear, maintainable API documentation alongside the JSON output. • Actionable Tip: Link specific parts of the JSON to sections in your documentation to make it easy for developers to cross-reference. Best Practices for Commenting in JSON
4. Consistency in Commenting Strategy • Best Practice: Ensure your team follows a consistent strategy for adding comments to JSON, whether using _comment fields, pre-processing, or external documentation. • Tip: Create a style guide for JSON comments. This should outline when and where to use comments, which comment fields to use (e.g., _note vs. _comment), and how to handle comments during production.
5. Keep Comments Relevant and Concise • Best Practice: Comments should be short, descriptive, and explain the why behind decisions rather than the what (which should be evident from the structure). • Tip: Regularly review and update comments as the underlying JSON evolves. Outdated comments can cause confusion and lead to misunderstandings.
6. Avoid Over-Commenting • Best Practice: Don't overwhelm your JSON files with unnecessary comments. Reserve comments for areas that are non-intuitive or require additional explanation. • Data Insight: A survey conducted by Stack Overflow found that 55% of developers find excessive comments to be just as problematic as insufficient comments. This suggests that businesses should focus on clarity and conciseness.
7. Strip Comments for Production • Best Practice: Ensure that any non-standard comment fields or pre-processed comments are removed from JSON files before deployment to prevent bloating API responses or configuration files. • Tip: Use a build process that automatically strips comments before deployment, reducing the risk of exposing internal documentation in production environments. Case Studies: How Businesses Benefit from Commented JSON
8. Improving Developer Collaboration at a SaaS Company A SaaS company managing a complex microservices architecture struggled with coordinating JSON configurations across teams. They introduced _comment fields in their configuration files to explain dependencies between services and key settings. As a result, the development and operations teams were better aligned, reducing configuration errors by 25%.
9. Reducing Onboarding Time at a FinTech Firm A FinTech firm dealing with complex JSON data structures for financial transactions faced challenges onboarding new developers. By implementing a combination of JSON5 with comments during development and maintaining external documentation, the company reduced onboarding time by 15%, as new developers could more easily understand the purpose and structure of the JSON data.
10. Enhancing API Usability for a HealthTech Platform A HealthTech company used external documentation alongside JSON output to provide clear guidance to API consumers. This documentation included explanations of sensitive fields (such as personal health information) and optional fields for API clients to implement. As a result, API adoption increased by 30% over the course of six months, driven by the ease of understanding the JSON schema. Data-Driven Insights on the Importance of JSON Comments • Efficiency Gains: A 2022 study by Gartner found that teams utilizing commented JSON or clear external documentation reduced debugging time by 20%, suggesting that comments improve team productivity. • Error Reduction: According to a report from Red Hat, projects that included consistent commenting strategies in configuration files (including JSON) saw a 30% reduction in configuration-related errors. • API Adoption: A survey conducted by Postman found that APIs with well-documented JSON structures (whether through comments or external docs) had 40% higher adoption rates compared to APIs with insufficient documentation. Conclusion: Unlocking the Power of Comments in JSON for Business Success Although JSON doesn't natively support comments, businesses can employ strategic workarounds like comment fields, pre-processing, and external documentation to significantly improve the readability and maintainability of their JSON files. By adopting best practices such as consistent commenting, ensuring comments are concise, and stripping them from production files, businesses can achieve enhanced collaboration, faster debugging, and more efficient development workflows.