JSON Validator

Validate JSON and find the exact line and column of any error. Detect duplicate keys, spot fixable mistakes and check data against a JSON Schema with clear messages.

  • Free, no sign-up
  • Runs in your browser
  • Your data stays private

How to use the JSON Validator

  1. Paste your JSON in the first box.
  2. Optionally paste a JSON Schema in the second box.
  3. Press Validate and read the report, issues table and tree.

Why use this JSON Validator

  • Precise errorsLine, column and a highlighted snippet pinpoint the problem.
  • Schema checkingSupports type, required, properties, enum, ranges, patterns, formats, items, anyOf, oneOf, allOf and $ref.
  • WarningsFlags duplicate keys and numbers with more than 15 digits.
  • Fix hintsLists mistakes that auto-fix can repair, such as trailing commas.

Frequently asked questions

How do I check if my JSON is valid?

Paste it and press Validate. You get a clear pass or the exact position of the error.

Can I validate against a JSON Schema?

Yes. Paste the schema in the second box and every violation is listed with its path.

What are duplicate keys?

The same property name used twice in one object. Most parsers keep only the last value, so it is reported as a warning.

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