toolkit

JSON Validator

Runs in browser

Validate JSON syntax instantly

Drag and drop a JSON file here, or

Max 50MB

How to Use

Paste JSON or drag a file to validate. Toggle 'Live' for real-time checking.

You will see:

  • Valid/Invalid Status
  • Detailed Error Messages
  • Line Number of Error
  • Safe Local Validation

Validation Result

No validation yet

Enter JSON and click Validate

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YAML ↔ JSON

About JSON Validator

JSON Validation ensures your JSON data conforms to the official JSON specification (RFC 8259). This tool parses your JSON, identifies syntax errors, and provides detailed error messages to help you fix issues quickly.

Why Validate JSON?

  • Prevent Runtime Errors: Invalid JSON will crash your application when parsed
  • API Reliability: Validate API payloads before sending to avoid 400 Bad Request errors
  • Configuration Safety: Catch config file errors before deployment
  • Data Integrity: Ensure imported data is properly formatted
  • Debug Faster: Pinpoint exact error locations instead of guessing

JSON Specification Rules

  • Strings: Must be enclosed in double quotes ("), not single quotes
  • Keys: Must be strings (quoted)
  • Numbers: Cannot have leading zeros, must use decimal point (not comma)
  • Booleans: Only true and false (lowercase)
  • Null: Only null (lowercase, not undefined)
  • No trailing commas: Last element must not have a comma
  • No comments: Comments are not allowed in standard JSON

Common Validation Errors

Unexpected Token

Usually caused by trailing commas, missing quotes, or invalid characters. Check the line number in the error message.

Unexpected End of Input

Missing closing bracket ] or brace }. Count your opening and closing brackets.

Invalid Character

Special characters in strings must be escaped with backslash. Check for unescaped quotes or control characters.

Valid vs Invalid Examples

✓ Valid

{"name": "John", "age": 30}

✗ Invalid (single quotes)

{'name': 'John', 'age': 30}

✓ Valid

{"items": [1, 2, 3]}

✗ Invalid (trailing comma)

{"items": [1, 2, 3,]}

💡 Pro Tips

  • Always validate JSON before sending to production APIs
  • Use a linter in your IDE to catch JSON errors while editing
  • If you need comments, use JSONC or JSON5 formats (not standard JSON)
  • This tool runs locally — your data never leaves your browser

Further Reading