JSON Formatter
Validate, beautify, minify, and repair JSON data instantly. All processing happens locally in your browser for maximum privacy.
Your formatted JSON will appear here
Free Online JSON Formatter, Beautifier & Validator
Securely format, beautify, validate, minify, stringify, and escape/unescape JSON data instantly. All processing runs 100% in your browser—format JSON without uploading, ensuring maximum privacy for your sensitive data.
What is JSON?
JSON (JavaScript Object Notation) is a lightweight format for storing and transporting data. Ideally, it's easy for humans to read and write, and easy for machines to parse and generate.
Originally specified by Douglas Crockford in the early 2000s, it has replaced XML as the de facto standard for API communication and configuration files.
{
"tool": "Kunji.dev",
"features": ["Format", "Validate"],
"isSecure": true
}Beautify & Format
Format messy JSON into readable, nested structures with 2 or 4-space indentation.
Minify & Stringify
Compress JSON to a single line or convert to an escaped string for code use.
Escape / Unescape
Safely escape special characters for string embedding, or unescape JSON strings.
Validate & Fix
Real-time validation flags errors. Auto-repair fixes quotes and commas.
Sort Keys
Alphabetize object keys for deterministic output. Essential for diffing.
File Operations
Upload .json files, copy to clipboard, or download formatted results.
100% Client-Side
Processing runs in browser via JavaScript. No data leaks to any server.
Zero Limits
Handle large files restricted only by your device's RAM. No upload caps.
Common Use Cases
- API Response Debugging Paste raw JSON from network tabs to inspect nested data structures clearly.
- Log Analysis Format single-line JSON logs from servers to quickly spot errors and patterns.
- Data Migration & ETL Clean, sort, and verify large JSON datasets before importing into databases.
- Payload Building Construct and validate complex JSON payloads before sending them to API endpoints.
- Learning JSON Structure Experiment with nesting, arrays, and types to understand the format (great for beginners).
How to Use
Input Data
Paste JSON into the editor or upload a local .json file.
Validate
Errors are highlighted instantly with line numbers and fixes.
Format
Click Beautify to indent or Repair to fix syntax issues.
Export
Copy the clean code to clipboard or download the file.
Why choose Kunji.dev
| Feature | Kunji.dev | JSONLint |
|---|---|---|
| Privacy | Client-side | Server-side |
| Speed | Instant | Slow Lag |
| Auto-Repair | Automagic | Manual |
| Limits | Unlimited RAM | File Size Limit |
Frequently Asked Questions
Is this Online JSON Formatter secure?
Yes, completely. All processing happens 100% in your browser. Your data never leaves your device and is never sent to any server.
How do I validate JSON syntax errors?
Just paste your code. Our JSON Validator instantly highlights errors like missing commas or quotes, showing you exactly where the problem is.
Is there a file size limit for JSON files?
No hard limit. Since we process data locally, the limit depends on your device's RAM. We easily handle files larger than 100MB without lag.
Why does standard JSON not support comments?
The official JSON standard excludes comments to keep parsing simple. If you need comments for configuration, try using JSON5 or YAML instead.
What is the difference between Minify and Stringify?
Minify removes spaces to make the file smaller. Stringify turns the JSON into a text string (escaping quotes) so it can be used inside code.
How do I Escape or Unescape JSON strings?
Escape turns special characters (like quotes) into safe text (e.g., " becomes \") for use in code. Unescape reverses this to bring back the original JSON.
How can I sort JSON keys alphabetically?
Turn on the Sort Keys toggle. This organizes keys from A-Z, making it much easier to compare different versions of a file.
JSON vs XML: Which is better?
JSON is lighter, faster, and works natively with JavaScript, making it perfect for APIs. XML is better for complex documents with mixed content.
Can I convert JSON to CSV or Excel?
Not directly here yet, but formatted JSON is easy to convert. We're building a dedicated JSON to CSV Converter that will be linked here soon.
How do I format (beautify) JSON in JavaScript?
Use the native function: JSON.stringify(data, null, 2). The 2 adds 2 spaces of indentation to make it readable.
What is the difference between JSON and a JavaScript Object?
JSON is a text format for sharing data (keys need quotes). JS Objects are the actual data structures in code (keys don't always need quotes).
Does this tool support JSON5 or JSONC?
We strictly validate against Standard JSON (RFC 8259) for maximum compatibility. Comments and trailing commas will show as errors.
Is there a JSON Formatter API available?
This is currently a free client-side tool. We are exploring a developer API for programmatic validation and formatting—stay tuned.
Difference between Format and Beautify?
They are mostly the same. Formatting usually means fixing the structure, while Beautifying focuses on making it look good with proper indentation.