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JSON Validator

Validate JSON syntax instantly. Detect errors, find missing brackets, and check data integrity — all in your browser.

Instant syntax validationDetailed error messagesLine & position indicatorsFormat valid JSONMinify valid JSONCopy to clipboard

Input JSON

Formatted JSON

Output will appear here...

How to Validate JSON Online

  1. 1Paste or type your JSON data into the left input area
  2. 2The validator checks syntax in real time as you type
  3. 3Valid JSON shows a green checkmark; invalid shows the exact error
  4. 4Fix any reported errors using the line and position hints
  5. 5Optionally format or minify valid JSON using the mode toggle
  6. 6Click "Copy JSON" to copy the result to your clipboard

Frequently Asked Questions

What does a JSON validator check for?

It checks for matching braces and brackets, properly quoted keys and string values, valid data types, correct comma placement, and overall JSON syntax compliance per the ECMA-404 standard.

Why is my JSON invalid?

Common reasons include trailing commas after the last item, single quotes instead of double quotes, unquoted property keys, missing colons, and unclosed brackets or braces. The validator shows the exact error location.

Is my JSON data secure?

Absolutely. Validation runs entirely in your browser using JavaScript's native JSON.parse(). Your data never leaves your device — no server uploads, no logging.

Can it fix invalid JSON automatically?

The validator identifies and describes the error but does not auto-fix it, since the intended correction depends on context. It gives you the exact position so you can fix it quickly.

What size JSON can I validate?

The tool handles files up to 10 MB comfortably. Since everything runs client-side, performance depends on your device. The character counter helps you monitor file size.

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