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JSON Formatter & Validator

Paste JSON, get it pretty-printed or minified with proper indentation, and receive clear validation messages if your JSON is malformed. 100% in your browser.

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Quick answer

Paste your JSON below to validate it live. Use Format to pretty-print with 2 spaces, 4 spaces, or a tab, or Minify to compact it. Clear messages tell you exactly where any error is. All processing runs in your browser — nothing is sent to a server.

Waiting for JSON input…

How to format and validate JSON

Follow these three quick steps to clean up and check any JSON payload.

  1. Paste your JSON

    Paste or type your JSON into the input box.

  2. Check the validation banner

    A green badge means your JSON is valid. A red message pinpoints the error with line and column.

  3. Format, minify, or copy

    Click Format to pretty-print with your chosen indent, Minify to compact it, then Copy the result.

Key features

Live validation

See a green or red banner update as you type, with precise line and column for any error.

Format & minify

Pretty-print with 2 spaces, 4 spaces, or a tab, or collapse to a single line.

100% private

All processing runs locally in your browser — nothing is sent to a server.

Supported formats

  • Pretty-printed JSON (indent)
  • Minified JSON (single line)
  • Nested objects
  • Arrays

Privacy and security

Your JSON is processed entirely in your browser using JavaScript. We never see, store, or transmit what you paste.

Limitations

  • Only valid JSON is supported — single quotes, trailing commas and comments are not allowed by the JSON spec and will be flagged as errors.
  • No file upload support — paste JSON text only (no file input).
  • Very large inputs are processed in your browser and may be slower on low-end devices.

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Frequently asked questions

Is this tool free?

Yes — completely free, no sign-up required. All formatting and validation run in your browser and nothing is sent to a server.

How do I know if my JSON is valid?

As you type, a banner appears below the input showing 'Valid JSON — no errors found' in green, or a clear red message describing exactly what is wrong and where (line and column).

Can I pretty-print and minify JSON?

Yes. Use Format to pretty-print with your chosen indent (2 spaces, 4 spaces, or a tab), or use Minify to collapse it onto as few lines as possible.

Do you store my JSON?

No. Everything runs locally in your browser. Your JSON never leaves your device.

Does it work with large JSON?

There is no hard limit — everything runs in your browser. Very large JSON may slow things down, but for normal files it is instant.

Why does Chrome/Node reject my JSON sometimes?

If the validation flags an error, it is genuinely malformed — for example a trailing comma, a missing quote, or unescaped control characters. Read the line/column message to locate it.