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Online JSON Validator

No installation needed — works in any modern browser. Checks whether JSON is valid and pretty-prints it.

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Result

Validity

✓ Valid JSON

Structure

Top-level type: object (2 keys)

Formatted JSON

{ "hello": "world", "n": 42 }

Notes

  • · Runs entirely in your browser — nothing is uploaded.

Online JSON Validator — How It Works

Online JSON Validator — How It Works

No installation needed — works in any modern browser. This tool checks whether a block of text is valid JSON, reports the top-level structure (object, array, or primitive), and pretty-prints it if valid.

How it works

  1. The tool tries to parse your input with JSON.parse.
  2. If it succeeds, it shows ”✓ Valid JSON”, the structure (e.g. “object with 3 keys”), and a nicely indented version.
  3. If it fails, it shows ”✗ Invalid JSON” along with the parser’s error message — usually pointing at the exact problem (a trailing comma, missing quote, etc.).

Common JSON mistakes

  • Trailing commas after the last item in an object or array (not allowed in JSON).
  • Using single quotes instead of double quotes for strings and keys.
  • Unquoted object keys.
  • Missing or extra closing braces/brackets.

Try the Online JSON Validator — instant results, no sign-up.

FAQ

Is this free?

Yes — the Online JSON Validator runs entirely in your browser, no sign-up required.

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