JSON Validator Online
Check whether your JSON format is valid. Get clear error messages with approximate line and column — processed locally in your browser.
Your JSON is processed locally in your browser and is never uploaded to our server.
Input
Free JSON format checker
A JSON validator helps you confirm that a string follows correct JSON format rules (quotes, commas, brackets, and structure). Paste JSON, click Validate, and jump to the problem line when something is wrong.
Use this checker for API responses, config files, and payloads before you ship them. Invalid JSON fails silently in many apps—catching it early saves debugging time.
- Line/column oriented error hints
- Works with paste, upload, and keyboard shortcut (Ctrl+Enter)
- Private: validation stays in your browser
Most "invalid JSON" reports trace back to a handful of RFC 8259 violations: a trailing comma after the last array or object member ([1, 2, 3,]), unquoted or single-quoted keys ({name: 'Ann'} instead of {"name": "Ann"}), and control characters left unescaped inside strings. For example, {"active": True}fails because JSON's boolean literals are lowercase true/false— Python's capitalized Trueisn't valid JSON, a mistake that's common when copying values straight out of a Python dict.
Also try the JSON formatter, JSON validator, JSON minifier, or JSON viewer.
JSON Validator FAQ
- How do I validate JSON online?
- Paste JSON into the editor (or upload a .json file) and click Validate or press Ctrl+Enter. The tool highlights syntax problems with an approximate line and column.
- Is my JSON uploaded when I validate?
- No. Validation runs locally in your browser with the native JSON parser. Your data is not sent to our server for validation.
- What errors can a JSON validator catch?
- Common issues include missing commas, unquoted keys, trailing commas, mismatched brackets, and invalid escape sequences in strings.
- Can I jump to the error line?
- Yes. When validation fails, use the jump control on the error message to move the cursor to the reported line in the editor.