JSON Validator

Validate and format JSON with error detection.

100% Private - Your text never leaves your browser

📝 JSON Input

🔍 Validation Result

Paste JSON to validate

About JSON Validator

Validate JSON syntax with detailed error messages, line numbers, and automatic formatting. See JSON structure statistics. This free online tool processes your text instantly in your browser - no data is ever sent to any server, ensuring complete privacy.

How to Use JSON Validator

Paste or type your text in the input field on the left
The result appears automatically in the output field
Adjust any options below the text fields if available
Click "Copy Result" to copy the output to your clipboard
Use "Download" to save the result as a text file

Features

✓100% Free - No registration required
✓Instant processing as you type
✓Complete privacy - works offline
✓No file size limits
✓Works on all devices
✓Download results as text file

Why Use Our JSON Validator?

Unlike other online tools that require uploads or send your data to servers, our json validator runs entirely in your browser using JavaScript. This means your sensitive text never leaves your computer, making it perfect for processing confidential documents, personal information, or any text you want to keep private. The tool is also lightning-fast since there's no network latency involved.

When to Use This Tool

API Development

Validate JSON request/response payloads before sending to ensure proper API communication.

Data Validation

Check if JSON data is syntactically correct before importing into databases or applications.

Debugging JSON Errors

Identify syntax errors with precise line numbers and helpful error messages.

Configuration Files

Validate JSON config files for applications, package.json, tsconfig.json, etc.

Examples

Valid JSON Object

Input

{"name": "John", "age": 30, "city": "New York"}

Output

✓ Valid JSON
{
  "name": "John",
  "age": 30,
  "city": "New York"
}

💡 JSON is valid and automatically formatted with proper indentation

Invalid JSON (Missing Quote)

Input

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

Output

✗ Invalid JSON at line 1: Unexpected token J in JSON

💡 String values must be in quotes

Complex Nested Structure

Input

{"users": [{"id": 1, "name": "Alice"}, {"id": 2, "name": "Bob"}]}

Output

✓ Valid JSON (2 objects, 1 array, 6 total keys)

💡 Validates complex nested structures and provides statistics

Common Mistakes to Avoid

⚠️

Using single quotes instead of double quotes

Solution: JSON requires double quotes (") for strings, not single quotes ('). Use {"key": "value"} not {'key': 'value'}

⚠️

Trailing commas in objects or arrays

Solution: JSON does not allow trailing commas. Remove the comma after the last element: [1, 2, 3] not [1, 2, 3,]

⚠️

Using undefined, NaN, or Infinity

Solution: JSON only supports null, not undefined, NaN, or Infinity. Convert these to null or string values.

⚠️

Comments in JSON

Solution: Standard JSON does not support comments. Remove // or /* */ comments before validation.

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