Convert JSON to JSON5 Online Free — Add Comments & Trailing Commas
Drag & drop your .json file here, or click to browse
Converts to JSON5 on secure servers · 1 free a day, files up to 25 MB · no signup
Your first conversion each day is free (files up to 25 MB). A $2.99 one-time Day Pass unlocks 24 hours and ends by itself.
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: October 2026
Convert JSON to JSON5 free online. Modernize JSON config files to JSON5 format with support for comments. Your file is uploaded over an encrypted connection and converted on our server.
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
Developers
- Convert JSON config files to JSON5 for compatibility with different tools or frameworks
- Transform JSON API responses to JSON5 for debugging, logging, or documentation
Data Analysts
- Convert JSON exports to JSON5 for importing into spreadsheet software, databases, or BI tools
- Transform JSON datasets to JSON5 for sharing with teammates who use different analysis tools
System Administrators
- Convert JSON configuration to JSON5 when migrating between infrastructure tools or platforms
- Transform JSON log exports to JSON5 for ingesting into monitoring or analysis systems
How to Convert JSON to JSON5
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1
Upload your JSON file
Drag and drop your JSON configuration file onto the converter, or click to browse. Both strict JSON and relaxed JSON formats are supported.
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2
Automatic JSON5 conversion
The converter processes your JSON using the json5 library, preserving all data while enabling JSON5 syntax features like comments and trailing commas.
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3
Download modernized config
Save your converted JSON5 file. The output maintains full data fidelity while supporting human-friendly syntax for better maintainability.
Convert JSON to JSON5 via API
Integrate this conversion into your pipeline with 3 lines of code. Free tier: 25 conversions/month.
curl -X POST https://changethisfile.com/v1/convert \ -H "Authorization: Bearer YOUR_API_KEY" \ -F "file=@input.json" \ -F "target=json5" \ -o output.json5 --fail
YOUR_API_KEY with your free key — no credit card needed.
Frequently Asked Questions
Your file is uploaded over an encrypted connection and converted on our server. 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.
This conversion runs on our server, so your file is uploaded over an encrypted connection. Files up to 15MB are deleted as soon as the converted file is sent back; larger files run as a background job and are deleted automatically about a day later. We don't share your files.
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.
Free conversions accept files up to 25MB. A one-time $2.99 Day Pass raises the limit to 100MB and unlocks unlimited conversions for 24 hours.
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.
Your first conversion each day is free, with no signup and no watermark, for files up to 25MB. For more conversions the same day or files up to 100MB, a one-time $2.99 Day Pass unlocks unlimited conversions for 24 hours. No account or subscription is needed.
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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