JSON Formatter & Validator

Paste your JSON — format, validate, minify, or download it instantly.

Raw or minified JSON is nearly impossible to read. This formatter parses your JSON, validates it for syntax errors, and outputs clean, indented, human-readable code — the same formatting your IDE provides, but accessible from any browser. It handles nested objects, large arrays, and edge cases like Unicode strings and special characters.

Formatted JSON will appear here...
Size (original)0 B
Size (formatted)0 B
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How to Format JSON Online

  1. Paste your JSON — copy raw, minified, or malformed JSON into the input box.
  2. Click "Format / Pretty Print" — the JSON is instantly beautified with 2-space indentation and proper line breaks.
  3. Check for errors — if the JSON is invalid, you'll see a clear error message. Fix the issue and try again.
  4. Optionally minify — click "Minify" to remove all whitespace and compress the JSON for use in production.
  5. Copy or download — use the Copy button or download the formatted JSON as a .json file.

The 7 JSON Errors That Break Everything

JSON looks like JavaScript but is far stricter. These are the errors behind virtually every "Unexpected token" message:

ErrorBrokenValid
Trailing comma{"a": 1,}{"a": 1}
Single quotes{'a': 1}{"a": 1}
Unquoted key{a: 1}{"a": 1}
Comments{"a": 1} // noteJSON has no comments — remove them
undefined / NaN{"a": undefined}{"a": null}
Unescaped quote in string{"msg": "say "hi""}{"msg": "say \"hi\""}
Leading zeros{"n": 007}{"n": 7}

Paste failing JSON above — the validator pinpoints the exact line and character. If your data comes from JavaScript code (single quotes, comments), it is JavaScript object notation, not JSON: run it through JSON.stringify at the source rather than hand-fixing.

Frequently Asked Questions

What does this JSON formatter do? ▼
It takes raw or minified JSON and formats it with proper indentation (2 spaces) so it's easy to read. It also validates JSON syntax and reports errors clearly, and can minify JSON to reduce file size.
Is my data safe? ▼
Yes. Everything runs locally in your browser. No data is transmitted to any server. This makes it safe to use with sensitive or private JSON data.
What is the difference between formatting and minifying JSON? ▼
Formatting (pretty printing) adds whitespace, line breaks, and indentation to make JSON human-readable. Minifying removes all unnecessary whitespace to reduce file size for faster API responses and data transfer.
Why is my JSON invalid? ▼
Common JSON errors include: trailing commas after the last property or array item, using single quotes instead of double quotes, unquoted property names, missing commas between items, and including comments (which are not supported in standard JSON).
What is JSON used for? ▼
JSON (JavaScript Object Notation) is used to transmit data between servers and web applications, store configuration files, define API request and response bodies, and exchange structured data between systems. It is the most widely used data format for REST APIs.
Can I format very large JSON files? ▼
Yes — since everything runs in your browser there is no upload limit. However, extremely large JSON (100MB+) may slow down your browser. For very large files, consider using a command-line tool like jq or python -m json.tool.

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