Convert JSON to JSON5 Online Free — Add Comments & Trailing Commas

Drag & drop your .json file here, or click to browse

Converts to JSON5 in your browser · first daily conversion free · no signup

Your first conversion each day is free. 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: March 2026

Quick Answer

Convert JSON to JSON5 free online. Modernize JSON config files to JSON5 format with support for comments. Free, no signup, files stay in your browser.

First daily conversion free No signup required Files stay on your device Instant conversion Updated May 2026

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

Validate the converted JSON5 output with a linter to catch any structural issues from the conversion

Watch for data type coercion (e.g., numbers becoming strings) when converting between JSON and JSON5

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

Check that column delimiters and quote escaping are handled correctly in the converted JSON5 file

Preview the first few rows of the JSON5 output to verify headers and data alignment

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

Back up the original JSON config before converting, especially for production systems

Test the converted JSON5 in a staging environment before deploying to production

How to Convert JSON to JSON5

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.
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.
3

Download modernized config

Save your converted JSON5 file. The output maintains full data fidelity while supporting human-friendly syntax for better maintainability.

Automate this conversion

Convert JSON to JSON5 via API

Integrate this conversion into your pipeline with 3 lines of code. Free tier: 25 conversions/month.

The free converter above runs entirely in your browser — your file is never uploaded. This optional API is a separate server-side endpoint for automating conversions at scale.

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

const form = new FormData();
form.append('file', fileInput.files[0]);
form.append('target', 'json5');

const res = await fetch('https://changethisfile.com/v1/convert', {
  method: 'POST',
  headers: { 'Authorization': 'Bearer YOUR_API_KEY' },
  body: form
});
const blob = await res.blob(); // your converted JSON5 file

Replace YOUR_API_KEY with your free key — no credit card needed.

Get a free API key

Frequently Asked Questions

How does ChangeThisFile convert JSON to JSON5?

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.

What are the main advantages of JSON5 over JSON?

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.

Are my JSON files uploaded to any servers?

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.

Will my JSON data be preserved exactly?

Yes. The conversion maintains perfect data fidelity — all values, structure, and data types are preserved. Only the syntax is enhanced to support JSON5 features.

Can I add comments to the converted JSON5 file?

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.

Do all tools support JSON5 format?

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.

Is JSON5 compatible with standard JSON?

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.

What's the file size difference between JSON and JSON5?

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.

Can I convert large JSON configuration files?

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.

Does this work for package.json files?

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.

Is this conversion free?

Yes, completely free. There's no cost, no signup required, no watermarks, and no limits on the number of files you can convert.

Can I convert multiple JSON files at once?

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.

Related Conversions

Compare JSON vs JSON5

Related Tools

Free tools to edit, optimize, and manage your files.

Data Prettify Data Validate Merge CSV

Read our guides on file formats and conversion

Ready to convert your file?

Convert JSON to JSON5 instantly — free, no signup required.

Start Converting