Convert JSON to JSON5 Online Free — Add Comments & Trailing Commas
Modernize JSON config files to JSON5 format with support for comments, trailing commas, and unquoted keys. Perfect for build configurations, settings files, and developer-friendly configs.
By ChangeThisFile Team · Last updated: March 2026
Convert JSON to JSON5 instantly in your browser — files never leave your device. 100% free, no signup, no software install.
Convert JSON to JSON5
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JSON vs JSON5: Format Comparison
Key differences between the two formats
| Feature | JSON | JSON5 |
|---|---|---|
| Comments | Not allowed — causes syntax errors | Single-line (//) and multi-line (/* */) comments supported |
| Trailing commas | Forbidden — strict syntax requirement | Allowed in objects and arrays for cleaner diffs |
| Object keys | Must be double-quoted strings | Unquoted identifiers allowed (foo: "bar") |
| String quotes | Double quotes only | Single or double quotes supported |
| Multi-line strings | Requires \n escape sequences | Template literal-style line breaks |
| Numbers | Decimal only (no 0x, no Infinity) | Hexadecimal (0xFF), Infinity, NaN supported |
| Browser support | Universal native support | Requires json5 library or transpilation |
| Use case | Data interchange, APIs | Configuration files, build tools |
When to Convert
Common scenarios where this conversion is useful
Modernizing build configuration files
Convert strict JSON config files like package.json, tsconfig.json, or webpack.config.json to JSON5 format for better maintainability with inline documentation and cleaner syntax.
Adding comments to settings files
Transform application configuration files from JSON to JSON5 to include explanatory comments for complex settings, environment variables, or feature flags.
Improving team config readability
Convert shared project configuration files to JSON5 format so team members can document configuration choices directly in the file with comments and cleaner formatting.
Preparing configs for human editing
Transform machine-generated JSON configs to JSON5 format for manual editing, allowing developers to add trailing commas and comments without breaking syntax.
Migration to modern config standards
Update legacy JSON configuration files to JSON5 format as part of modernizing codebases that support the more flexible JSON5 specification.
Who Uses This Conversion
Tailored guidance for different workflows
Frontend Developers
- Convert package.json and build config files to JSON5 format for better documentation and team collaboration
- Transform application configuration files to support inline comments explaining complex feature flags or environment settings
DevOps Engineers
- Convert application config JSON files to JSON5 for better documentation of deployment settings and environment variables
- Transform infrastructure-as-code configuration files to JSON5 format for improved maintainability and team understanding
Project Maintainers
- Convert open source project configuration files to JSON5 for contributor-friendly documentation and self-explanatory settings
- Transform complex build configuration files to JSON5 format so contributors can understand configuration choices
Frequently Asked Questions
Your JSON file is processed directly in your browser using the json5 JavaScript library. The conversion preserves all data while enabling JSON5 syntax features like comments, trailing commas, and unquoted keys.
JSON5 allows comments for documentation, trailing commas for cleaner git diffs, unquoted object keys for readability, and more flexible string and number formats — making configuration files much more human-friendly.
No. All conversion happens locally in your browser using client-side JavaScript. Your configuration files never leave your device, ensuring privacy for proprietary or sensitive configs.
Yes. The conversion maintains perfect data fidelity — all values, structure, and data types are preserved. Only the syntax is enhanced to support JSON5 features.
The conversion itself doesn't add comments automatically, but the resulting JSON5 format supports both single-line (//) and multi-line (/* */) comments that you can add manually.
JSON5 support varies by tool. Many modern build tools, bundlers, and config systems support JSON5, but traditional JSON parsers require the json5 library. Check your specific tool's documentation.
JSON5 is a superset of JSON, meaning all valid JSON is also valid JSON5. However, JSON5 features like comments and trailing commas are not valid in standard JSON parsers.
The converted JSON5 file is typically the same size or slightly larger than the original JSON, depending on whether you add comments or use the more flexible syntax features.
Yes. Since conversion happens in your browser, there's no arbitrary file size limit. Large configuration files, package.json files, or complex configs convert instantly.
The conversion works for any JSON file, including package.json. However, note that npm and yarn expect strict JSON format — JSON5 package files won't work with standard Node.js package managers.
Yes, completely free. There's no cost, no signup required, no watermarks, and no limits on the number of files you can convert.
Currently, files are converted one at a time. Simply upload your next JSON file after downloading the converted JSON5 result to process multiple configuration files.
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